Retinal Vein Occlusion in Sub Saharan Africa: A Systematic Review and Meta-analysis

Retinal Vein Occlusion in Sub Saharan Africa: A Systematic Review and Meta-analysis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Retinal Vein Occlusion in Sub Saharan Africa: A Systematic Review and Meta-analysis Mohamed Ismail, Intisar Khalafalla, Zakaria Omar Sheck, Sowda Abdikarim Sheikh Isse, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8388967/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background: Retinal vein occlusion (RVO) is a very common retinal vascular disorder and a significant cause of visual loss worldwide. However, the burden, proportion of subtypes, and risk factors associated with RVO in Sub-Saharan Africa (SSA) remain poorly explored and undefined. This systematic review and meta-analysis were conducted to assess the prevalence of RVO in Sub-Saharan Africa and its subtypes, risk factors, and presentation. Methods : A systematic search was conducted on PubMed/MEDLINE, African Journals Online, and Google Scholar for observational studies featuring RVO prevalence data published since January 2000 until October 2025. Selection of observational studies was performed in accordance with the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement 2020. Random-effects meta-analysis methods were used in obtaining prevalence rates, with heterogeneity tested with Cochran’s Q test and degree of heterogeneity determined with I² statistics. Funnel plots and regression test through Egger’s test were done to test publication bias. Results: Eight studies from five SSA countries (Nigeria, Liberia, Cameroon, Democratic Republic of Congo, and Benin) with a cumulative total of 158,940 participants were found to satisfy the criteria. RVO prevalence varied from 0.03% in general ophthalmology clinics to 10.8% among tertiary referral centers for retinal diseases. Overall, The Pooled prevalence of RVO among SSA countries was found to be 0.8% (95% CI = 0.2%–3.1%) , with a degree of heterogeneity of 97.9% (p < 0.001 Central retinal vein occlusion (CRVO) was common in studies from Nigeria (58% - 74%), Liberia (60%), and Cameroon (55%) , while branch retinal vein occlusion (BRVO) was found more frequently in Democratic Republic of Congo (69.2%). Benin reported almost equal incidents of CRVO and BRVO (50% each). The prevalent risk factor was systemic hypertension, followed by diabetes mellitus , while glaucoma was identified as the dominant eye complication. Visual acuities at presentation were poor in all studies. There was no evidence of publication bias (Egger's test, p ≈ 0.20). Conclusion : RVO is rare in general ophthalmic referrals in SSA but presents an important proportion in retina referrals. RVO demonstrates distinct links with systemic vascular risk factors, thus emphasizing the importance of comprehensive cardiovascular and ophthalmological management, as well as population-based epidemiological studies, in SSA. retinal vein occlusion Africa prevalence meta-analysis hypertension branch retinal vein occlusion central retinal vein occlusion risk factors Figures Figure 1 Figure 2 Figure 3 Figure 4 INTRODUCTION Retinal vein occlusion (RVO) is a thrombo-occlusive disease of the retinal veins, the second most common retinovascular disease after diabetic retinopathy( 1 ). Anatomically, RVO is classified into three conditions: central retinal vein occlusion (CRVO), branch retinal vein occlusion (BRVO), or hemiretinal vein occlusion (HRVO) depending on the retinal area where the obstruction occurs. Notably, RVO is mostly characterized by sudden, painless loss of vision, often resulting in complications such as macular edema, retinal hemorrhage, or neovascularization, which is a great source of visual morbidity primarily among middle-aged to older persons( 2 ). Globally, the epidemiological features of RVO have been adequately documented in Europe, Asia, and North America. A combined analysis by Rogers et al. found that the mean prevalence of RVO is 0.5%, with a relative risk of four times more in BRVO than CRVO. Estimated prevalence of 16 million by 2008 among the global population showed that RVO is a significant public health issue( 3 ). Known risk factors include advancing age, hypertension, and atherosclerotic cardiovascular disease, with other associations including diabetes mellitus, hyperlipidemia, and glaucoma. Of these, hypertension is recognized as the prime risk factor that is potentially modifiable, with open-angle glaucoma being directly related to CRVO because of the resultant raised intra-venous pressure of the globe. These data clearly indicate that there is a strong correlation between RVO and vascular diseases( 4 ). Despite this, the extent of RVO burden and its characteristics in Sub Saharan Africa (SSA) remain poorly established. Historically, the priorities of eye care in SSA have predominantly involved infectious causes of blindness, as well as diseases that affect younger individuals, with the result that little attention has been given to age-related retinal vascular diseases such as RVO. However, the observed trends of an increase in life expectancy and the rising prevalence of non-communicable diseases such as hypertension and diabetes would tend to indicate that RVO could become a progressively more significant agent of blindness in SSA. Available studies in hospitals in SSA suggest that RVO does occur there, though the rates remain immensely variable. Thus, whereas a study in a general eye clinic in Benin found a prevalence of 0.03%( 5 ), there were more than 7% with RVO in a retinal clinic in Nigeria( 6 ). Furthermore, some studies from the African continent showed that the relative proportion of CRVO is higher compared to that of BRVO, whereas in other populations, BRVO is dominant. This difference could be a real representation of the disparity among the various regions or could result from some inherent differences in the referral rates among the two conditions( 6 – 9 ). Currently, there is no study that presents a Meta-analysis of the data of RVO in SSA. Therefore, the purpose of this systematic review and meta-analysis is to provide an estimate of RVO in SSA, as well as to evaluate its subtypes, risk factors, heterogeneity, and publications. METHODS PROTOCOL AND SEARCH STRATEGY This systematic review was carried out following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. A predefined, non-registered protocol was developed with the inclusion criteria, objectives, and analysis plan. We searched PubMed/MEDLINE, Embase, African Journals Online, and Google Scholar for studies that were published between January 2000 and October 2025, with data on the prevalence of retinal vein occlusion (RVO) in Sub-Saharan Africa. Search expressions were “retinal vein occlusion,” “CRVO,” “BRVO,” and geographic expressions. Inclusion criteria were observational studies in SSA that quantitatively documented the number of RVO with a denominator. Case reports, studies that failed to provide data on prevalence, and studies from North Africa were excluded. SELECTION AND DATA EXTRACTION Selection of studies was done using the PRISMA guidelines. There were a number of records retrieved from database searching. These were screened for duplicates. Titles and abstracts were screened for relevance. Articles that could be relevant were evaluated for full-text analysis. Exclusion of studies was for lack of data on prevalence, inability to distinguish between RVO and other forms of retinal diseases, or for studies that were not from Sub-Saharan Africa. A total of eight studies were selected for analysis using the PRISMA flow diagram. Data was extracted for each of the studies that were eventually included, with information gathered for author, year of publication, country of origin, study design, number of subjects studied, number of RVO cases documented, as well as the prevalence. When possible, additional data for study type of RVO (CRVO, BRVO, HRVO), patient demographics, risk factors, and outcomes were extracted. Studies were taken from Nigeria (four), Liberia, Cameroon, DR Congo, and Benin, with study sizes varying from less than 200 to almost 100,000 in various settings that were often largely retrospective. Table 1 Characteristics of studies on RVO in Sub-Saharan Africa. Table 1 Characteristics of studies included in the systematic review and meta-analysis of retinal vein occlusion in Africa Study (Author, Year) Country Study Design Sample Size RVO Cases Okonkwo et al., 2023( 10 ) Nigeria Cross-sectional, hospital-based (eye clinics) 8614 72 Singh & Pillai, 2024( 11 ) Liberia Retrospective clinic review 10813 111 Fiebai et al., 2014( 6 ) Nigeria Retrospective, retina clinic 364 27 Uhumwangho et al., 2015( 2 ) Nigeria Retrospective, retina clinic 185 12 Adenuga et al., 2015( 1 ) Nigeria Retrospective, general eye clinic 3821 37 Koki et al., 2017( 12 ) Cameroon Cross-sectional, retina referral center 5055 70 Joseph et al., 2025( 13 ) DRC (Lubumbashi) Cross-sectional, retina referral center 33041 30 Odoulami et al., 2018( 5 ) Benin (Cotonou) Retrospective, eye clinics 96047 30 QUALITY ASSESSMENTS A literature analysis of the research involved the application of adapted Joanna Briggs Institute criteria for the measurement of prevalence in Table 2. All studies for the analysis were of a hospital setting, causing a risk of selection bias. Data were likely to be incomplete, despite standardized definitions of RVO diagnosis and subtype. A risk factor could either be measured or self-reported. It was found that the current evidence is of moderate quality with no population-based studies as a major limitation JBI QUALITY ASSESSMENT TABLE CAPTION Table 2 Summary of methodological quality assessment of included prevalence studies using the Joanna Briggs Institute (JBI) checklist, showing that most studies were of moderate to high quality. Study (Author, Year) Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Q9 Overall quality Okonkwo et al., 2023( 10 ) Yes Yes Yes Yes Yes Yes Yes Yes Unclear High Singh & Pillai, 2024( 11 ) Yes Yes Yes Yes Yes Yes Yes Yes Unclear High Fiebai et al., 2014( 6 ) Yes No Yes Yes Yes Yes Yes Yes Unclear Moderate Uhumwangho et al., 2015( 2 ) Yes No Yes Yes Yes Yes Yes Yes Unclear Moderate Adenuga et al., 2015( 1 ) Yes No Yes Yes Yes Yes Yes Yes Unclear Moderate Koki et al., 2017( 12 ) Yes Yes Yes Yes Yes Yes Yes Yes Unclear High Joseph et al., 2025( 13 ) Yes Yes Yes Yes Yes Yes Yes Yes Unclear High Odoulami et al., 2018( 5 ) Yes No Yes Yes Yes Yes Yes Yes Unclear Moderate DATA SYNTHESIS AND STATISTICAL ANALYSIS A random-effects approach with the DerSimonian & Laird estimators was employed in conducting the meta-analysis, expecting substantial heterogeneity in the point estimates of the prevalence of retinal vein occlusion among the individual studies. Additionally, logging the individual study proportions before calculating the pooled estimate helps to alleviate differences in variance for low values of the prevalence. Meanwhile, heterogeneity was evaluated using the Cochran’s Q test, as well as the I2 statistic, with scores > 75% representing high heterogeneity. Furthermore, the between-study variance was also calculated. An exploratory meta-regression was carried out using the country as a categorical moderator for the investigation of possible causes of heterogeneity using a mixed-effects model with Knapp-Hartung adjustment. Publication bias was checked graphically with funnel plots and with Egger’s regression test, with some interpretation of the latter likely to be compromised by the small number of studies. All calculations were made using the JASP software package (version 0.16), with independent verification using RevMan. RESULTS STUDY SELECTION AND CHARACTERISTICS Eight studies satisfied the inclusion criteria, offering information on retinal vein occlusion (RVO) from five Sub-Saharan African nations: Nigeria( 1 , 2 , 6 , 7 ) (four studies), Liberia( 11 ), Cameroon( 12 ), Democratic Republic of Congo( 13 ), and Benin( 5 ). All eight studies were observation studies carried out in hospitals. These were conducted between 2014–2025. Sample sizes varied widely, ranging from 185 to 96,047 participants. The number of reported RVO cases ranged from 12 to 111 across studies. Study characteristics are summarized in Table 1 . Prevalence of Retinal Vein Occlusion The reported prevalence of RVO varied markedly across studies. The lowest prevalence was reported in a general ophthalmology clinic in Benin (0.03%; 30/96,047), while a study from the DRC reported a prevalence of 0.09% (30/33,041). In Nigeria, prevalence estimates in general ophthalmology clinics ranged from 0.8% to 1.4%. Higher prevalence rates were consistently observed in retina specialty clinics. Studies from Nigeria reported prevalences of 7.4% and 10.8% in tertiary retina referral centers. Using a random-effects meta-analysis, the pooled prevalence of RVO in Sub-Saharan Africa was 0.8% (95% CI: 0.2%–3.1% ), corresponding to approximately 8 cases per 1,000 ophthalmic patients (Fig. 2 ). The 95% prediction interval was wide (approximately 0.01%–32% ), indicating substantial variability across settings. There was marked heterogeneity among studies (Cochran’s Q ≈ 127, p < 0.001; I² = 97.9% ), suggesting that nearly all observed variability was due to real differences between studies rather than chance. Meta-regression using country as a moderator did not significantly explain heterogeneity ( p = 0.163). However, studies from Nigeria reported significantly higher prevalence estimates compared with Benin ( p = 0.048). RVO SUB-TYPE DISTRIBUTION In the sub-Saharan Africans (SSA), there is considerable disparity among retinal vein occlusion (RVO) subtype prevalence observed in various studies. Contrary to the global epidemiological trends that record a higher frequency of branch retinal vein occlusion (BRVO), various studies carried out in Africa show a higher proportion of central retinal vein occlusion (CRVO). Fiebai et al.( 6 ), for example, found that CRVO accounted for 74%, while Uhumwangho et al( 2 ). found that CRVO accounted for 68%, with the latter study having a smaller number of BRVO and hemiretinal vein occlusion (HRVO)( 2 ). These trends were also found in studies carried out in Liberia and Cameroon, with both finding CRVO to constitute the majority of the diagnosed RVO cases( 11 , 12 ). CRVO was found to constitute about 58% of RVO cases in Nigeria, as discovered in their multicenter study. Notwithstanding, the trend is not consistent. A study from the Democratic Republic of Congo showed that the prevalence of BRVO is the highest (69.2%), matching global trends more accurately( 13 ). Similarly, a study from Benin observed almost an equal number of CRVO and BRVO cases, with HRVO being less. This could be attributed to differences in referral patterns or settings. CRVO tends to result in more severe vision loss, which could potentially get referred to a tertiary center, whereas milder cases of BRVO could go unnoticed, especially in resource-poor settings. It would appear that the subtype pattern of RVO observed by SSA is highly dependent on settings, with CRVO being predominantly found in a tertiary care setting or a balanced pattern in a hospital setting with likely dominance by BRVO. The distribution of RVO subtypes varied across studies, with CRVO predominating in most Nigerian, Liberian, and Cameroonian series, while BRVO was more frequent in the Democratic Republic of Congo (Figure ) RISK FACTORSAND COMORBID CONDITIONS FOR RVOPATIENTS Systemic hypertension : came out as the consistently recorded risk factor among RVO patients in SSA from the various studies that were reviewed. More than half of the patients with RVO developed hypertension, as shown by various studies. Uhumwangho et al.( 2 ) showed that 70% of RVO patients developed hypertension, while Josephet al.( 13 ) Showed that 57.7% of RVO patients developed hypertension in the DRC. Multi-center information in Nigeria also established a significant relationship between RVO and hypertension, thus reiterating its position as the principal risk factor that can be altered among these patients. This is consistent with various studies that showed that high blood pressure is a risk factor for retinal venous thrombosis. Diabetes mellitus : was the second most frequent systemic comorbidity in RVO. The prevalence of diabetic patients among those with RVO ranged between 25% and 45%. This is a significant observation in the Nigerian reports and the study that took place in the DRC. It is evident that diabetic patients significantly contribute to microvascular damage as well as the risk of thrombosis. In some cases, hypothyroidism, hypertension, and diabetic conditions were frequent among patients with RVO. Glaucoma : stood out as the frequently recorded ocular risk factor, more so in the Nigerian and Benin cohorts, with about 20–25% of RVO patients also having glaucoma. The presence of high prevalence of primary open-angle glaucoma in Africans makes it significant, more so in CRVO given the role of intraocular pressure in impeded venous outflow. Other possible risk factors : like smoking, hyperlipidemia, obesity, and thrombophilic disorders were variably mentioned or not evaluated in the majority of the studies. Smoking was rarely recorded, making it difficult to evaluate its importance for SSA. Although hyperlipidemia was variably mentioned in some of the studies, it was not evaluated. Thus, it would appear that current evidence indicates that RVO in SSA is caused by established risk factors for CV events, whereas factors related to lifestyle and hematology are inadequately investigated. Clinical Outcomes & Other Findings Though the review largely focused on prevalence and risk factors, there were some studies that showed important clinical results for RVO patients. Visual acuities of patients at presentation were poor. Odoulami et al.( 5 ) Found that 67.6% of the eyes were visually impaired with vision worse than 3/60, which is legally blind. Similarly, Fiebai et al( 6 ). found severe visual impairment in most CRVO patients as well as in a significant number of BRVO patients, indicating that the patients often present late with end results of macular edema or ischemia. Uhumwangho et al( 2 ). found a high complication rate that included macular edema (68%), retinal neovascularization (23%), and neovascular glaucoma (13.6%). As far as management is concerned, it was observed in the DRC study that pan-retinal laser photocoagulation and intravitreal therapies like corticosteroids or anti-VEGF factors were performed in selected cases. However, limited availability of such therapies could be one of the factors responsible for poor visual outcomes in such patients. Bilateral RVO was rarely observed but was found to occur between 10–26% in various studies, which is often an indicator of severe underlying diseases. META-ANALYTIC TESTS OF BIAS A funnel plot of the logit transformations of the prevalences by the standard error of the latter was used to explore for any bias. While there is some heterogeneity here, with some outlying observations, care is advised in interpretation. A certain degree of asymmetry is observed, driven by the presence of some small studies reporting high prevalences (two of them: Fiebai 2014( 6 ), Uhumwangho 2016( 2 )) on one side of the plot, with the other side dominated by some larger studies reporting low prevalences (two of them: Odoulami 2018( 5 ), Joseph 2025( 13 )). This could represent either a small-study effect or differences in study setting (smaller studies would likely derive from retina clinics with higher rates). Egger’s test for the presence of this type of asymmetry was not significant (p ≈ 0.20 for this analysis). This test would lack power with such few studies, and no conclusion can or should be drawn. While it seems likely that centers with few or no cases of RVO did not undertake any study, it is impossible to verify either hypothesis. In Funnel plot Fig. 4 , there is no evidence of publication bias, despite the limited power of this test. This asymmetry could very likely be accounted for by other factors that one would expect to observe (specialty practice vs. general practices), so it does not appear that there is any systematic overestimation of prevalence as a result of publication bias among the data that is currently available despite the heterogeneity. DISCUSSION This is the first systematic review and meta-analysis that comprehensively synthesizes data on retinal vein occlusion (RVO) in SSA. Using eight studies, the prevalence of approximately 0.8% for RVO among the ophthalmic population was found to be suggestive of a low prevalence of RVO in general eye outpatient settings in SSA (less than 1 in 100), with considerable variability. Such a high degree of heterogeneity (I² ≈ 98%) is expected, given that among the study settings could be general outpatient ophthalmology practices through to specialist retina referral services. In context, the pooled prevalence of the SSA is comparable to that of non-African group studies. A major global meta-analysis found a prevalence of about 0.52% for any RVO, which is significantly higher among older individuals( 8 ). While the SSA prevalence is marginally higher, it is taken from a hospital-based study, not from a population-based survey( 10 ). A broad confidence interval of 0.2–3.1% suggests that the prevalence of RVO could be similar or even higher in selected risk groups in other settings. A low prevalence of 0.03–0.09% in major general outpatient clinics in Benin or DRC implies that RVO is a small percentage of a broad spectrum of patients with various eye diseases, whereas retina specialist clinics had 7–10% of their patients with RVO, indicating significant importance of RVO among other severe retinal pathologies, including diabetic retinopathy, a major public health issue, or age-related macular degeneration( 2 ). One of the observed consistent results is that there is a strong link that was noticed between RVO and systemic vascular risk factors such as hypertension and diabetes mellitus. It was found that more than half of the patients with RVO were suffering from hypertension in almost all the studies that were reviewed( 8 , 10 ). This is important since it establishes that it is the key modifiable risk factor for SSA. Due to low levels of both patient and physician hypertension awareness and poor rates of hypertension control in the Africa region, it is possible that RVO could be a sentinel presentation of systemic vascular disease. Almost one-fourth to almost half of patients with RVO were found to be suffering from diabetes mellitus( 8 , 14 ). Glaucoma showed the most frequent association with RVO as comorbidity, occurring in up to one-fourth of patients with CRVO. This association is of great significance in SSA, where primary open-angle glaucoma is found to be highly prevalent, with many of these cases being undiagnosed. Against this background, intraocular pressure could potentially predispose patients to CRVO due to poor venous drainage, while ischemic CRVO could progress to neovascular glaucoma, signifying a bidirectional relationship. Specialists in SSA, who practice multiple specializations owing to manpower shortages, should remain alert for a simultaneous association of glaucoma with RVO or RVO with glaucoma( 15 – 17 ). An interesting additional finding is the relative preponderance of CRVO over BRVO observed in some of the African studies, in contrast to what is observed in population-based studies in developed countries, in which BRVO is generally more frequent. No doubt this is a reflection of referral patterns, since CRVO tends to produce more severe vision loss( 10 ). That this is true is suggested by the finding in the DRC study that indeed found BRVO to predominate, as would be expected. The age of presentation of RVO in SSA seems to be slightly younger than that of Western civilization, with mean ages of 60 years or slightly younger. This could be related to demographics, the onset of poorly controlled hypertension, or survivorship bias. Nevertheless, it means that one should not view RVO as being predominantly a condition of older people in SSA, since the middle-aged with vascular risk factors contribute to the pool of patients suffering from RVO. The clinical outcomes were poor, with many patients presenting with severe visual impairment or blindness. There were high levels of macular edema, neovascularization, and neovascular glaucoma, suggesting late presentation and poor access to care. While some of the tertiary centers mentioned the use of photocoagulation therapy and intravitreal therapy, the availability of anti-VEGF therapy is still imperfect( 18 ). Firstly, from the public health point of view, these results illustrate the escalating importance of RVO in SSA with the recent increases in NCDs. Improving hypertension and diabetic care could also alleviate the number of RVO and other vascular forms of blindness. Programs for the visually impaired, historically driven by cataract and infectious causes of blindness, could increasingly turn their attention to retinal vascular diseases. STRENGTHS AND LIMITATIONS This is the first combined analysis of the prevalence and characteristics of retinal vein occlusion (RVO) in Sub-Saharan Africa (SSA), integrating new information from a number of countries. Application of strict methods for data analysis using random effects preserves the integrity of the study findings. Thorough selection of data for the subtypes of RVO made it possible to discuss the findings at the regional level. However, certain limitations must be acknowledged. Firstly, all the studies were hospitalized, which decreases the ability to generalize the findings for the whole population. Additionally, the number of studies was limited, which decreased the possibility of conducting subgroup analysis, with significant heterogeneity that reduced the confidence in the pooled analysis. Moreover, there was a variability in reporting risk factors, with limited information on the role of smoking, lipid disorders, among other risk factors. Lastly, the absence of population studies, together with limited data on treatment outcomes, reveals areas of research that should be explored. These factors notwithstanding, this literature review is significant for establishing a benchmark to comprehend RVO in the context of SSA and the importance of both population-based research, surveillance, and systematic as well as ocular care. CONCLUSION In conclusion, retinal vein occlusion is a recognized but rare form of retinopathy in Sub-Saharan Africa with a prevalence of about one percent or lower among patients seeking care for their eyes. This data suggests that retinal vein occlusions in SSA occur more among middle-aged to older patients, who predominantly present with associated systemic hypertension, followed by diabetes mellitus, which is consistent with risk factors for globally encountered retinal vein occlusions. Of significance is that, relative to the other clinical practices mentioned, it would appear that the frequency of retinal vein occlusions related to the center of the retina is at least as great, or perhaps more common, than that of the branches—a reflection of severity likely driving patient attendance. Such marked variability of prevalence rates strongly suggests that the burden of retinal vein occlusions is likely to vary from rare in a general clinic to a significant proportion of patients in a retina practice. The meta-analysis draws attention to the need for care coordination: the care of RVO patients in Africa must incorporate risk factors for cardiovascular diseases, whereas the management of systemic diseases could potentially alleviate retinal complications like RVO. Focusing on public health issues, since the epidemiologic transition in Africa is progressing into a phase with more emphasis on non-communicable diseases, RVO would potentially become more recognized in the region and would need more attention. Prospective epidemiologic studies would be important in determining the true incidence of RVO in the community, and treatment must be made widely available to prevent blindness among those with RVO. Conclusion While RVO is not one of the major causes of blindness in SSA at present, it still remains a significant contributing factor to blindness in the older population and is a reflection of poor systemic health. It is important to note that improving these systemic risk factors would provide a two-fold gain for both general and eye health. It is suggested that the service delivery for ophthalmology in Africa needs to improve the patient work-up for RVO patients systemically by integrating with other specialists to provide a collective treatment plan for RVO patients. This would help SSA adequately confront the growing burden of retinal vascular diseases in the senior members of their communities. Declarations Ethics approval and consent to participate Not applicable, as this study is based solely on analysis of previously published data and does not involve any human participants or identifiable individual data. Consent for publication Not applicable. Availability of data and resources. All data generated or analyzed throughout this study are contained in this published article. Competing interests The authors have no competing interests to declare. Funding This study did not get any particular financial support from public, commercial, or non-profit funding agencies. Authors' contributions Dr.Mohamed Farah Ismail conceived and planned the study, conducted the literature search, executed data extraction, conducted statistical analysis, and prepared the manuscript. Prof. Intisar Khalafalla critically reviewed the methodology, validated the data, and revised manuscripts. All authors read and approved the final manuscript. Acknowledgments The authors appreciate the support from the Department of Ophthalmology, Kampala International University Teaching Hospital. References Adenuga OO, Ramyil AV, Odugbo OP, Oyediji FJ. PREVALENCE, PATTERN AND RISK FACTORS FOR RETINAL VASCULAR OCCLUSIONS IN A TERTIARY HOSPITAL IN JOS, NIGERIA. Niger J Med J Natl Assoc Resid Dr Niger. 2015;24(4):331–6. Uhumwangho O, Oronsaye D. Retinal vein occlusion in Benin City, Nigeria. Niger J Surg. 2016;22(1):17. Rogers S, McIntosh RL, Cheung N, Lim L, Wang JJ, Mitchell P, et al. The Prevalence of Retinal Vein Occlusion: Pooled Data from Population Studies from the United States, Europe, Asia, and Australia. Ophthalmology. 2010 Feb;117(2):313-319.e1. Kolar P. Risk factors for central and branch retinal vein occlusion: a meta-analysis of published clinical data. J Ophthalmol. 2014;2014:724780. Odoulami L, Savage Y, Alamou S, Sounouvou I, Tchabi S, Doutetien C. Retinal vein occlusion in Cotonou. Austin J Clin Ophthalmol. 2018;5:1091. Fiebai B, Ejimadu C, Komolafe R. Incidence and risk factors for retinal vein occlusion at the University of Port Harcourt Teaching Hospital, Port Harcourt, Nigeria. Niger J Clin Pract. 2014;17(4):462. Adenuga OO, Ramyil AV, Odugbo OP, Oyediji FJ. Prevalence, pattern and risk factors for retinal vascular occlusions in a tertiary hospital in Jos, Nigeria. Niger J Med. 2015;24(4):331–6. Rogers S, McIntosh RL, Cheung N, Lim L, Wang JJ, Mitchell P, et al. The prevalence of retinal vein occlusion: pooled data from population studies from the United States, Europe, Asia, and Australia. Ophthalmology. 2010;117(2):313–9. Kolar P. Risk factors for central and branch retinal vein occlusion: a meta‐analysis of published clinical data. J Ophthalmol. 2014;2014(1):724780. Okonkwo ON, Adenuga OO, Nkanga D, Ovienria W, Ibanga A, Agweye CT, et al. Prevalence and Systemic Associations of Retinal Vascular Occlusions in Sub-Saharan Africa. Ann Afr Med. 2023 July;22(3):279–85. Singh G, Pillai S. Demographic profile, prevalence, pattern, and risk factors for retinal vein occlusion in Liberia: A retrospective study. Oman J Ophthalmol. 2024;17(2):205–9. Koki G, Yaya G, Epée E, Bilong Y, Noa G, Helles G, et al. Epidémiologie et clinique des occlusions veineuses rétiniennes en milieu hospitalier camerounais. Health Sci Dis. 2018;19(1). Joseph KM, JP LW. Les occlusions veineuses rétiniennes: facteurs étiologiques et évolutifs des patients suivis aux cliniques universitaires de Lubumbashi. Rev Afr Médecine Santé Publique. 2025;8(1):228–38. Adeloye D, Abaa DQ, Owolabi EO, Ale BM, Mpazanje RG, Dewan MT, et al. Prevalence of hypercholesterolemia in Nigeria: a systematic review and meta-analysis. Public Health. 2020;178:167–78. Thomas GN, Kiew SY, Singh P, Dmitriev P, Thomas AS, Fekrat S. Central retinal vein occlusion: the effect of antiplatelet and anticoagulant agents. J Vitreoretin Dis. 2022;6(2):97–103. Hayreh SS. Retinal vein occlusion. Indian J Ophthalmol. 1994;42(3):109–32. Orth DH, Patz A. Retinal branch vein occlusion. Surv Ophthalmol. 1978;22(6):357–76. Daien V, Eldem BM, Talks JS, Korobelnik JF, Mitchell P, Finger RP, et al. Real-world data in retinal diseases treated with anti-vascular endothelial growth factor (anti-VEGF) therapy–a systematic approach to identify and characterize data sources. BMC Ophthalmol. 2019;19(1):206. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8388967","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":575280228,"identity":"43b64109-2ee3-434f-8705-48c5949ad39d","order_by":0,"name":"Mohamed Ismail","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABaElEQVRIie2RPWvCUBRA70PIpM36JG26db4SCBaF/pAuCYIuBpykWwNCulhdE+iPCAh2VQI6NDpHMhgp7dQhQykZUuizkSYoDt0KzRku78I73C+AnJw/CLcNSocFmqTile7Mw3CbTACIjkcUTBUJyaxJTMCjSkJGUe2Ce1Eo/iiHn0/4JzUMEK55ofdih10gj5zLPdfjWB14jYCYHQf4uwlXfk8bo9qIssY062Emr8wlFC77i7mkGahaXhOJjQ5QV+GE04xSsr8V21Nkv2Sw1rylImg6qrbfBhIwBTzgBJoq/GIUJUrrw/80oAjrNxSqcUY531NAG++qtGWfGEBx4soCcDtl2xgypRxmZxlXFaSaZba7q/6SYlmfNSr3hiRZ61ecmtgqVly1V0s3dj5cjFbRTV0b0tbYi7r12yE40yCKxbOB62w2/bgminNnuor2d00PHgnsNGw6dh52qd9CDqrk5OTk/B++AH2IjMu0BVwmAAAAAElFTkSuQmCC","orcid":"","institution":"Kampala International University","correspondingAuthor":true,"prefix":"","firstName":"Mohamed","middleName":"","lastName":"Ismail","suffix":""},{"id":575280231,"identity":"f48d7ed7-f795-4405-b1e8-fc634a7a3b97","order_by":1,"name":"Intisar Khalafalla","email":"","orcid":"","institution":"Kampala International University","correspondingAuthor":false,"prefix":"","firstName":"Intisar","middleName":"","lastName":"Khalafalla","suffix":""},{"id":575280233,"identity":"7fd4a7a3-5564-45e4-b59d-715b6f538c9e","order_by":2,"name":"Zakaria Omar Sheck","email":"","orcid":"","institution":"Kampala International University","correspondingAuthor":false,"prefix":"","firstName":"Zakaria","middleName":"Omar","lastName":"Sheck","suffix":""},{"id":575280239,"identity":"e7f3c40d-f223-4ed5-9116-c2eb2e124e80","order_by":3,"name":"Sowda Abdikarim Sheikh Isse","email":"","orcid":"","institution":"Kampala International University","correspondingAuthor":false,"prefix":"","firstName":"Sowda","middleName":"Abdikarim Sheikh","lastName":"Isse","suffix":""},{"id":575280240,"identity":"d0623ec7-c307-4a3b-a049-57d4c1a213c1","order_by":4,"name":"Fathi Abdi Farah","email":"","orcid":"","institution":"Kampala International University","correspondingAuthor":false,"prefix":"","firstName":"Fathi","middleName":"Abdi","lastName":"Farah","suffix":""},{"id":575280242,"identity":"40b9d988-8b19-4ebe-8586-0d2ffdee1921","order_by":5,"name":"Abdikarim Ahmed Warsame","email":"","orcid":"","institution":"Kampala International University","correspondingAuthor":false,"prefix":"","firstName":"Abdikarim","middleName":"Ahmed","lastName":"Warsame","suffix":""},{"id":575280244,"identity":"d336b801-48b3-43a2-9f0f-94e8a7132492","order_by":6,"name":"Ibrahim Abdirahman Mohamed","email":"","orcid":"","institution":"Kampala International University","correspondingAuthor":false,"prefix":"","firstName":"Ibrahim","middleName":"Abdirahman","lastName":"Mohamed","suffix":""},{"id":575280246,"identity":"22109173-8f7a-4d95-9af7-3690082bdaf7","order_by":7,"name":"Amina Mohamed Mire","email":"","orcid":"","institution":"Kampala International University","correspondingAuthor":false,"prefix":"","firstName":"Amina","middleName":"Mohamed","lastName":"Mire","suffix":""},{"id":575280247,"identity":"ea6e6035-cd18-46f4-b182-11dbd85fbc05","order_by":8,"name":"Bahja Ahmed Mumin","email":"","orcid":"","institution":"Kampala International University","correspondingAuthor":false,"prefix":"","firstName":"Bahja","middleName":"Ahmed","lastName":"Mumin","suffix":""}],"badges":[],"createdAt":"2025-12-17 20:23:18","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8388967/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8388967/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":100426694,"identity":"2e5eae67-201f-4803-ae89-e3b5d830ae0a","added_by":"auto","created_at":"2026-01-16 14:19:48","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":364102,"visible":true,"origin":"","legend":"","description":"","filename":"RVOVERSIONONE.docx","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/1cbe3de4dceb80264c7d9cca.docx"},{"id":100546507,"identity":"ad6dc4f6-88bd-43cf-8359-3c5e8d710b32","added_by":"auto","created_at":"2026-01-19 08:09:59","extension":"json","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":10584,"visible":true,"origin":"","legend":"","description":"","filename":"302988b410fc4500a020074d2d2ddc54.json","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/327ce9491809bfbe340f01dd.json"},{"id":100546464,"identity":"a3a5449c-e4ce-4d45-b538-bcb88724f3f9","added_by":"auto","created_at":"2026-01-19 08:08:59","extension":"xml","order_by":2,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":88551,"visible":true,"origin":"","legend":"","description":"","filename":"302988b410fc4500a020074d2d2ddc541enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/8c676187d9570f5083e8227c.xml"},{"id":100426589,"identity":"147d6ecc-c2bc-4e4f-941b-cf6f0fde1afc","added_by":"auto","created_at":"2026-01-16 14:19:44","extension":"eps","order_by":3,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":60505,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage1.eps","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/cc78fc30857f895241b47703.eps"},{"id":100426642,"identity":"ef62c432-1325-4ae6-abdd-c40efcc303a6","added_by":"auto","created_at":"2026-01-16 14:19:46","extension":"eps","order_by":4,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":549,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage2.eps","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/4185d67690a4c34fa75590f2.eps"},{"id":100426688,"identity":"ccfcfa83-7ffb-499f-9267-375c978c4892","added_by":"auto","created_at":"2026-01-16 14:19:48","extension":"eps","order_by":5,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":62866,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage3.eps","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/b43956925a775ed261b254ed.eps"},{"id":100426744,"identity":"fb7e079f-0a3e-4430-b0d0-4f4358c726ca","added_by":"auto","created_at":"2026-01-16 14:19:53","extension":"eps","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":608,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage4.eps","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/ed220989954dc75a867cf7dd.eps"},{"id":100546204,"identity":"92d3a145-1003-4f7d-8c3b-85f19319b559","added_by":"auto","created_at":"2026-01-19 08:00:32","extension":"eps","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":137734,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage5.eps","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/10f7804692be8a005e1cc836.eps"},{"id":100426814,"identity":"7185f94a-b90f-4a85-bb21-2259ca4efa9a","added_by":"auto","created_at":"2026-01-16 14:19:55","extension":"eps","order_by":8,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":87895,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage6.eps","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/16334eddc0e93b4b39be39f0.eps"},{"id":100426609,"identity":"38fcde3b-f2f2-4551-832e-d7916f1afbd5","added_by":"auto","created_at":"2026-01-16 14:19:44","extension":"eps","order_by":9,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":404,"visible":true,"origin":"","legend":"","description":"","filename":"drawingimage7.eps","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/38d5ce7b78e378daf3418471.eps"},{"id":100546101,"identity":"d7fbd50d-4ec7-4097-be7a-2999f966cca5","added_by":"auto","created_at":"2026-01-19 07:53:15","extension":"jpeg","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":85432,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/f69bb0435dffe24d0f3dc68d.jpeg"},{"id":100426686,"identity":"947e1127-53e2-472f-97e2-c5353396a333","added_by":"auto","created_at":"2026-01-16 14:19:48","extension":"jpeg","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":180832,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/532954f66b150d680e570811.jpeg"},{"id":100426541,"identity":"dcae9aa6-01aa-4ff4-91ce-610bee874ecb","added_by":"auto","created_at":"2026-01-16 14:19:41","extension":"jpeg","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":137426,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/ccaa63477c3d9310c7a0e573.jpeg"},{"id":100426619,"identity":"b6455bee-65b6-4d66-9c50-1a40e64bdc87","added_by":"auto","created_at":"2026-01-16 14:19:44","extension":"jpeg","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":37522,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/7655c5316bdeef0521b3c1a3.jpeg"},{"id":100426547,"identity":"7998855c-fb47-4231-95d1-c9ecb1629743","added_by":"auto","created_at":"2026-01-16 14:19:41","extension":"jpeg","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":93360,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/3922981f32ae18f7fbd902b7.jpeg"},{"id":100426568,"identity":"91a684d6-144d-4b14-b6bb-ef9b531bdbcc","added_by":"auto","created_at":"2026-01-16 14:19:42","extension":"jpeg","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":66486,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage6.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/fff5ac34d36983a7e12eb2f3.jpeg"},{"id":100426546,"identity":"077949ac-61cb-4564-b687-f7d71a105d0d","added_by":"auto","created_at":"2026-01-16 14:19:41","extension":"png","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":93776,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/4b0dffc569c0764e5418b72d.png"},{"id":100426655,"identity":"eed1e8b0-7752-446a-91df-ffb62eb3ce06","added_by":"auto","created_at":"2026-01-16 14:19:47","extension":"png","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":99758,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/17bbfa1fd985cf8e918ff3b3.png"},{"id":100546725,"identity":"03d4c391-78db-4a01-82ff-902c74389d36","added_by":"auto","created_at":"2026-01-19 08:12:11","extension":"png","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":130940,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/a438fb78e385f927f09bb682.png"},{"id":100426573,"identity":"b14e5578-0fac-4c22-a29d-120863374184","added_by":"auto","created_at":"2026-01-16 14:19:42","extension":"png","order_by":19,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":13589,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/db0209e6c34645e5a1226ec6.png"},{"id":100546500,"identity":"27d4f9d1-ac00-4b8d-b261-7981fdcea475","added_by":"auto","created_at":"2026-01-19 08:09:57","extension":"png","order_by":20,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":30686,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/1035a90cf6509ca2b354f51b.png"},{"id":100426685,"identity":"c19df6d8-3dfe-476c-a1a7-1ef837f9ec2b","added_by":"auto","created_at":"2026-01-16 14:19:48","extension":"png","order_by":21,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":28910,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/4926afb49b1754621d269606.png"},{"id":100426716,"identity":"3dff9a52-b3ed-49da-9eef-e31faddad126","added_by":"auto","created_at":"2026-01-16 14:19:52","extension":"png","order_by":22,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":7343,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/9ac10c5f861d2aea34b55bee.png"},{"id":100426673,"identity":"f7def277-0e62-4783-b94f-d993838b49e2","added_by":"auto","created_at":"2026-01-16 14:19:48","extension":"png","order_by":23,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":20917,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/05c34486d85fee2359aaf6b2.png"},{"id":100546223,"identity":"3a6e803d-7dc5-47df-ba8c-278cc6eaedb8","added_by":"auto","created_at":"2026-01-19 08:02:34","extension":"png","order_by":24,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":10260,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/d757ff60dc9dccc731a91501.png"},{"id":100426705,"identity":"551ea530-6523-4b62-92f4-d580ae2b0bf6","added_by":"auto","created_at":"2026-01-16 14:19:50","extension":"png","order_by":25,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":27655,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/fe673abfa800db6523c57f0e.png"},{"id":100426544,"identity":"ce8b8414-1165-49a3-b59e-d4fb103616bf","added_by":"auto","created_at":"2026-01-16 14:19:41","extension":"png","order_by":26,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":26757,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/9c9c741443fdb797ec729fab.png"},{"id":100426697,"identity":"903c76fc-54eb-4cc3-b7c3-a6effd503ed2","added_by":"auto","created_at":"2026-01-16 14:19:49","extension":"png","order_by":27,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":40543,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/0ee47fb0c3ae75e68b79098d.png"},{"id":100426645,"identity":"2e5abfad-da9d-42cd-812b-6b64c00e60a4","added_by":"auto","created_at":"2026-01-16 14:19:46","extension":"xml","order_by":28,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":84434,"visible":true,"origin":"","legend":"","description":"","filename":"302988b410fc4500a020074d2d2ddc541structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/9ad21e0f5ba71d26573b95f6.xml"},{"id":100426709,"identity":"9f42d17f-e4d5-41a5-8aa7-ff2fb8eebef9","added_by":"auto","created_at":"2026-01-16 14:19:51","extension":"html","order_by":29,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":101320,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/2ad728a57a6f6b4a328715ad.html"},{"id":100426549,"identity":"4bb3d8a8-b92b-4e95-913b-e1416ee7ee90","added_by":"auto","created_at":"2026-01-16 14:19:41","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":55867,"visible":true,"origin":"","legend":"\u003cp\u003ePRISMA 2020 flow diagram\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/4e70e256aa7de89668a71e93.png"},{"id":100426632,"identity":"bdc368e0-0720-481e-abbd-96eff50627d4","added_by":"auto","created_at":"2026-01-16 14:19:45","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":74678,"visible":true,"origin":"","legend":"\u003cp\u003eCAPTION: Forest plot showing the pooled prevalence of retinal vein occlusion in Sub-Saharan Africa using a random-effects meta-analysis. Individual study estimates with 95% confidence intervals are displayed, together with the overall pooled estimate. Substantial between-study heterogeneity was observed (I² = 97.9%), and the prediction interval indicates wide variability across clinical settings.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/505c06ae413048350d3de671.png"},{"id":100426658,"identity":"7a436629-6377-45a9-847a-dc5842dc0587","added_by":"auto","created_at":"2026-01-16 14:19:48","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":64288,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of retinal vein occlusion subtypes (central and branch retinal vein occlusion) across included studies in Sub-Saharan Africa.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/8b651e9a9fd0625b49928da7.png"},{"id":100426784,"identity":"8e8c6371-5aed-4717-bf9d-7bf729e3493b","added_by":"auto","created_at":"2026-01-16 14:19:54","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":94182,"visible":true,"origin":"","legend":"\u003cp\u003eCaption: Funnel plot assessing publication bias in studies reporting the prevalence of retinal vein occlusion in Sub-Saharan Africa. Each point represents an individual study plotted by effect size against its standard error. Visual inspection showed no marked asymmetry, and Egger’s regression test indicated no statistically significant publication bias\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/c5c1d83e0d645f129525e44c.png"},{"id":104297740,"identity":"3c038e7b-dce7-4a7f-8cd8-c080cbebbac8","added_by":"auto","created_at":"2026-03-10 08:13:02","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1160648,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8388967/v1/92880a0a-08b5-4334-9cba-c19a5967c763.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eRetinal Vein Occlusion in Sub Saharan Africa: A Systematic Review and Meta-analysis \u003c/p\u003e","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eRetinal vein occlusion (RVO) is a thrombo-occlusive disease of the retinal veins, the second most common retinovascular disease after diabetic retinopathy(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). Anatomically, RVO is classified into three conditions: central retinal vein occlusion (CRVO), branch retinal vein occlusion (BRVO), or hemiretinal vein occlusion (HRVO) depending on the retinal area where the obstruction occurs. Notably, RVO is mostly characterized by sudden, painless loss of vision, often resulting in complications such as macular edema, retinal hemorrhage, or neovascularization, which is a great source of visual morbidity primarily among middle-aged to older persons(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eGlobally, the epidemiological features of RVO have been adequately documented in Europe, Asia, and North America. A combined analysis by Rogers et al. found that the mean prevalence of RVO is 0.5%, with a relative risk of four times more in BRVO than CRVO. Estimated prevalence of 16\u0026nbsp;million by 2008 among the global population showed that RVO is a significant public health issue(\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). Known risk factors include advancing age, hypertension, and atherosclerotic cardiovascular disease, with other associations including diabetes mellitus, hyperlipidemia, and glaucoma. Of these, hypertension is recognized as the prime risk factor that is potentially modifiable, with open-angle glaucoma being directly related to CRVO because of the resultant raised intra-venous pressure of the globe. These data clearly indicate that there is a strong correlation between RVO and vascular diseases(\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDespite this, the extent of RVO burden and its characteristics in Sub Saharan Africa (SSA) remain poorly established. Historically, the priorities of eye care in SSA have predominantly involved infectious causes of blindness, as well as diseases that affect younger individuals, with the result that little attention has been given to age-related retinal vascular diseases such as RVO. However, the observed trends of an increase in life expectancy and the rising prevalence of non-communicable diseases such as hypertension and diabetes would tend to indicate that RVO could become a progressively more significant agent of blindness in SSA. Available studies in hospitals in SSA suggest that RVO does occur there, though the rates remain immensely variable. Thus, whereas a study in a general eye clinic in Benin found a prevalence of 0.03%(\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e), there were more than 7% with RVO in a retinal clinic in Nigeria(\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFurthermore, some studies from the African continent showed that the relative proportion of CRVO is higher compared to that of BRVO, whereas in other populations, BRVO is dominant. This difference could be a real representation of the disparity among the various regions or could result from some inherent differences in the referral rates among the two conditions(\u003cspan additionalcitationids=\"CR7 CR8\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). Currently, there is no study that presents a Meta-analysis of the data of RVO in SSA. Therefore, the purpose of this systematic review and meta-analysis is to provide an estimate of RVO in SSA, as well as to evaluate its subtypes, risk factors, heterogeneity, and publications.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003ePROTOCOL AND SEARCH STRATEGY\u003c/h2\u003e \u003cp\u003e This systematic review was carried out following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. A predefined, non-registered protocol was developed with the inclusion criteria, objectives, and analysis plan. We searched PubMed/MEDLINE, Embase, African Journals Online, and Google Scholar for studies that were published between January 2000 and October 2025, with data on the prevalence of retinal vein occlusion (RVO) in Sub-Saharan Africa. Search expressions were \u0026ldquo;retinal vein occlusion,\u0026rdquo; \u0026ldquo;CRVO,\u0026rdquo; \u0026ldquo;BRVO,\u0026rdquo; and geographic expressions. Inclusion criteria were observational studies in SSA that quantitatively documented the number of RVO with a denominator. Case reports, studies that failed to provide data on prevalence, and studies from North Africa were excluded.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSELECTION AND DATA EXTRACTION\u003c/h3\u003e\n\u003cp\u003e Selection of studies was done using the PRISMA guidelines. There were a number of records retrieved from database searching. These were screened for duplicates. Titles and abstracts were screened for relevance. Articles that could be relevant were evaluated for full-text analysis. Exclusion of studies was for lack of data on prevalence, inability to distinguish between RVO and other forms of retinal diseases, or for studies that were not from Sub-Saharan Africa. A total of eight studies were selected for analysis using the PRISMA flow diagram.\u003c/p\u003e \u003cp\u003eData was extracted for each of the studies that were eventually included, with information gathered for author, year of publication, country of origin, study design, number of subjects studied, number of RVO cases documented, as well as the prevalence. When possible, additional data for study type of RVO (CRVO, BRVO, HRVO), patient demographics, risk factors, and outcomes were extracted. Studies were taken from Nigeria (four), Liberia, Cameroon, DR Congo, and Benin, with study sizes varying from less than 200 to almost 100,000 in various settings that were often largely retrospective.\u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e \u003cb\u003eCharacteristics of studies on RVO in Sub-Saharan Africa.\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCharacteristics of studies included in the systematic review and meta-analysis of retinal vein occlusion in Africa\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStudy (Author, Year)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCountry\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eStudy Design\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSample Size\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRVO Cases\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOkonkwo et al., 2023(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNigeria\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCross-sectional, hospital-based (eye clinics)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e8614\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e72\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSingh \u0026amp; Pillai, 2024(\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLiberia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRetrospective clinic review\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e10813\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e111\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFiebai et al., 2014(\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNigeria\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRetrospective, retina clinic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e364\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUhumwangho et al., 2015(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNigeria\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRetrospective, retina clinic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e185\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdenuga et al., 2015(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNigeria\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRetrospective, general eye clinic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3821\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e37\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKoki et al., 2017(\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCameroon\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCross-sectional, retina referral center\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e5055\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eJoseph et al., 2025(\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDRC (Lubumbashi)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCross-sectional, retina referral center\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e33041\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOdoulami et al., 2018(\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBenin (Cotonou)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRetrospective, eye clinics\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e96047\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eQUALITY ASSESSMENTS\u003c/h3\u003e\n\u003cp\u003eA literature analysis of the research involved the application of adapted Joanna Briggs Institute criteria for the measurement of prevalence in Table\u0026nbsp;2. All studies for the analysis were of a hospital setting, causing a risk of selection bias. Data were likely to be incomplete, despite standardized definitions of RVO diagnosis and subtype. A risk factor could either be measured or self-reported. It was found that the current evidence is of moderate quality with no population-based studies as a major limitation\u003c/p\u003e\n\u003ch3\u003eJBI QUALITY ASSESSMENT TABLE\u003c/h3\u003e\n\u003cp\u003e \u003cstrong\u003eCAPTION\u003c/strong\u003e \u003cp\u003e \u003cem\u003eTable\u0026nbsp;2 Summary of methodological quality assessment of included prevalence studies using the Joanna Briggs Institute (JBI) checklist, showing that most studies were of moderate to high quality.\u003c/em\u003e \u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e \u003ccolgroup cols=\"11\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStudy (Author, Year)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eQ1\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eQ2\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eQ3\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eQ4\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eQ5\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eQ6\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eQ7\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eQ8\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eQ9\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003eOverall quality\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOkonkwo et al., 2023(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eUnclear\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eHigh\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSingh \u0026amp; Pillai, 2024(\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eUnclear\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eHigh\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFiebai et al., 2014(\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eUnclear\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eModerate\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUhumwangho et al., 2015(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eUnclear\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eModerate\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdenuga et al., 2015(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eUnclear\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eModerate\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKoki et al., 2017(\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eUnclear\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eHigh\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eJoseph et al., 2025(\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eUnclear\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eHigh\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOdoulami et al., 2018(\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eUnclear\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eModerate\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eDATA SYNTHESIS AND STATISTICAL ANALYSIS\u003c/h3\u003e\n\u003cp\u003eA random-effects approach with the DerSimonian \u0026amp; Laird estimators was employed in conducting the meta-analysis, expecting substantial heterogeneity in the point estimates of the prevalence of retinal vein occlusion among the individual studies. Additionally, logging the individual study proportions before calculating the pooled estimate helps to alleviate differences in variance for low values of the prevalence. Meanwhile, heterogeneity was evaluated using the Cochran\u0026rsquo;s Q test, as well as the I2 statistic, with scores\u0026thinsp;\u0026gt;\u0026thinsp;75% representing high heterogeneity. Furthermore, the between-study variance was also calculated.\u003c/p\u003e \u003cp\u003eAn exploratory meta-regression was carried out using the country as a categorical moderator for the investigation of possible causes of heterogeneity using a mixed-effects model with Knapp-Hartung adjustment. Publication bias was checked graphically with funnel plots and with Egger\u0026rsquo;s regression test, with some interpretation of the latter likely to be compromised by the small number of studies. All calculations were made using the JASP software package (version 0.16), with independent verification using RevMan.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eSTUDY SELECTION AND CHARACTERISTICS\u003c/h2\u003e \u003cp\u003eEight studies satisfied the inclusion criteria, offering information on retinal vein occlusion (RVO) from five Sub-Saharan African nations: Nigeria(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e) (four studies), Liberia(\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e), Cameroon(\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e), Democratic Republic of Congo(\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e), and Benin(\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). All eight studies were observation studies carried out in hospitals. These were conducted between 2014\u0026ndash;2025.\u003c/p\u003e \u003cp\u003eSample sizes varied widely, ranging from 185 to 96,047 participants. The number of reported RVO cases ranged from 12 to 111 across studies. Study characteristics are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003ePrevalence of Retinal Vein Occlusion\u003c/h3\u003e\n\u003cp\u003eThe reported prevalence of RVO varied markedly across studies. The lowest prevalence was reported in a general ophthalmology clinic in Benin (0.03%; 30/96,047), while a study from the DRC reported a prevalence of 0.09% (30/33,041). In Nigeria, prevalence estimates in general ophthalmology clinics ranged from 0.8% to 1.4%.\u003c/p\u003e \u003cp\u003eHigher prevalence rates were consistently observed in retina specialty clinics. Studies from Nigeria reported prevalences of 7.4% and 10.8% in tertiary retina referral centers.\u003c/p\u003e \u003cp\u003eUsing a random-effects meta-analysis, the pooled prevalence of RVO in Sub-Saharan Africa was \u003cb\u003e0.8%\u003c/b\u003e (95% CI: \u003cb\u003e0.2%\u0026ndash;3.1%\u003c/b\u003e), corresponding to approximately \u003cb\u003e8 cases per 1,000 ophthalmic patients\u003c/b\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The 95% prediction interval was wide (approximately \u003cb\u003e0.01%\u0026ndash;32%\u003c/b\u003e), indicating substantial variability across settings.\u003c/p\u003e \u003cp\u003eThere was marked heterogeneity among studies (Cochran\u0026rsquo;s Q\u0026thinsp;\u0026asymp;\u0026thinsp;127, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001; \u003cb\u003eI\u0026sup2; = 97.9%\u003c/b\u003e), suggesting that nearly all observed variability was due to real differences between studies rather than chance.\u003c/p\u003e \u003cp\u003eMeta-regression using country as a moderator did not significantly explain heterogeneity (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.163). However, studies from Nigeria reported significantly higher prevalence estimates compared with Benin (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.048).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eRVO SUB-TYPE DISTRIBUTION\u003c/h2\u003e \u003cp\u003eIn the sub-Saharan Africans (SSA), there is considerable disparity among retinal vein occlusion (RVO) subtype prevalence observed in various studies. Contrary to the global epidemiological trends that record a higher frequency of branch retinal vein occlusion (BRVO), various studies carried out in Africa show a higher proportion of central retinal vein occlusion (CRVO). Fiebai et al.(\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e), for example, found that CRVO accounted for 74%, while Uhumwangho et al(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). found that CRVO accounted for 68%, with the latter study having a smaller number of BRVO and hemiretinal vein occlusion (HRVO)(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). These trends were also found in studies carried out in Liberia and Cameroon, with both finding CRVO to constitute the majority of the diagnosed RVO cases(\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e). CRVO was found to constitute about 58% of RVO cases in Nigeria, as discovered in their multicenter study.\u003c/p\u003e \u003cp\u003eNotwithstanding, the trend is not consistent. A study from the Democratic Republic of Congo showed that the prevalence of BRVO is the highest (69.2%), matching global trends more accurately(\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). Similarly, a study from Benin observed almost an equal number of CRVO and BRVO cases, with HRVO being less. This could be attributed to differences in referral patterns or settings. CRVO tends to result in more severe vision loss, which could potentially get referred to a tertiary center, whereas milder cases of BRVO could go unnoticed, especially in resource-poor settings. It would appear that the subtype pattern of RVO observed by SSA is highly dependent on settings, with CRVO being predominantly found in a tertiary care setting or a balanced pattern in a hospital setting with likely dominance by BRVO.\u003c/p\u003e \u003cp\u003eThe distribution of RVO subtypes varied across studies, with CRVO predominating in most Nigerian, Liberian, and Cameroonian series, while BRVO was more frequent in the Democratic Republic of Congo (Figure )\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eRISK FACTORSAND COMORBID CONDITIONS FOR RVOPATIENTS\u003c/h2\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eSystemic hypertension\u003c/b\u003e: came out as the consistently recorded risk factor among RVO patients in SSA from the various studies that were reviewed. More than half of the patients with RVO developed hypertension, as shown by various studies. Uhumwangho et al.(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e) showed that 70% of RVO patients developed hypertension, while Josephet al.(\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e) Showed that 57.7% of RVO patients developed hypertension in the DRC. Multi-center information in Nigeria also established a significant relationship between RVO and hypertension, thus reiterating its position as the principal risk factor that can be altered among these patients. This is consistent with various studies that showed that high blood pressure is a risk factor for retinal venous thrombosis.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eDiabetes mellitus\u003c/b\u003e: was the second most frequent systemic comorbidity in RVO. The prevalence of diabetic patients among those with RVO ranged between 25% and 45%. This is a significant observation in the Nigerian reports and the study that took place in the DRC. It is evident that diabetic patients significantly contribute to microvascular damage as well as the risk of thrombosis. In some cases, hypothyroidism, hypertension, and diabetic conditions were frequent among patients with RVO.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eGlaucoma\u003c/b\u003e: stood out as the frequently recorded ocular risk factor, more so in the Nigerian and Benin cohorts, with about 20\u0026ndash;25% of RVO patients also having glaucoma. The presence of high prevalence of primary open-angle glaucoma in Africans makes it significant, more so in CRVO given the role of intraocular pressure in impeded venous outflow.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eOther possible risk factors\u003c/b\u003e: like smoking, hyperlipidemia, obesity, and thrombophilic disorders were variably mentioned or not evaluated in the majority of the studies. Smoking was rarely recorded, making it difficult to evaluate its importance for SSA. Although hyperlipidemia was variably mentioned in some of the studies, it was not evaluated. Thus, it would appear that current evidence indicates that RVO in SSA is caused by established risk factors for CV events, whereas factors related to lifestyle and hematology are inadequately investigated.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eClinical Outcomes \u0026amp; Other Findings\u003c/h2\u003e \u003cp\u003eThough the review largely focused on prevalence and risk factors, there were some studies that showed important clinical results for RVO patients. Visual acuities of patients at presentation were poor. Odoulami et al.(\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e) Found that 67.6% of the eyes were visually impaired with vision worse than 3/60, which is legally blind. Similarly, Fiebai et al(\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). found severe visual impairment in most CRVO patients as well as in a significant number of BRVO patients, indicating that the patients often present late with end results of macular edema or ischemia. Uhumwangho et al(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). found a high complication rate that included macular edema (68%), retinal neovascularization (23%), and neovascular glaucoma (13.6%).\u003c/p\u003e \u003cp\u003eAs far as management is concerned, it was observed in the DRC study that pan-retinal laser photocoagulation and intravitreal therapies like corticosteroids or anti-VEGF factors were performed in selected cases. However, limited availability of such therapies could be one of the factors responsible for poor visual outcomes in such patients. Bilateral RVO was rarely observed but was found to occur between 10\u0026ndash;26% in various studies, which is often an indicator of severe underlying diseases.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eMETA-ANALYTIC TESTS OF BIAS\u003c/h2\u003e \u003cp\u003eA funnel plot of the logit transformations of the prevalences by the standard error of the latter was used to explore for any bias. While there is some heterogeneity here, with some outlying observations, care is advised in interpretation. A certain degree of asymmetry is observed, driven by the presence of some small studies reporting high prevalences (two of them: Fiebai 2014(\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e), Uhumwangho 2016(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e)) on one side of the plot, with the other side dominated by some larger studies reporting low prevalences (two of them: Odoulami 2018(\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e), Joseph 2025(\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e)). This could represent either a small-study effect or differences in study setting (smaller studies would likely derive from retina clinics with higher rates). Egger\u0026rsquo;s test for the presence of this type of asymmetry was not significant (p\u0026thinsp;\u0026asymp;\u0026thinsp;0.20 for this analysis). This test would lack power with such few studies, and no conclusion can or should be drawn. While it seems likely that centers with few or no cases of RVO did not undertake any study, it is impossible to verify either hypothesis.\u003c/p\u003e \u003cp\u003eIn Funnel plot Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, there is no evidence of publication bias, despite the limited power of this test. This asymmetry could very likely be accounted for by other factors that one would expect to observe (specialty practice vs. general practices), so it does not appear that there is any systematic overestimation of prevalence as a result of publication bias among the data that is currently available despite the heterogeneity.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003e This is the first systematic review and meta-analysis that comprehensively synthesizes data on retinal vein occlusion (RVO) in SSA. Using eight studies, the prevalence of approximately 0.8% for RVO among the ophthalmic population was found to be suggestive of a low prevalence of RVO in general eye outpatient settings in SSA (less than 1 in 100), with considerable variability. Such a high degree of heterogeneity (I\u0026sup2; \u0026asymp; 98%) is expected, given that among the study settings could be general outpatient ophthalmology practices through to specialist retina referral services.\u003c/p\u003e \u003cp\u003eIn context, the pooled prevalence of the SSA is comparable to that of non-African group studies. A major global meta-analysis found a prevalence of about 0.52% for any RVO, which is significantly higher among older individuals(\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). While the SSA prevalence is marginally higher, it is taken from a hospital-based study, not from a population-based survey(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). A broad confidence interval of 0.2\u0026ndash;3.1% suggests that the prevalence of RVO could be similar or even higher in selected risk groups in other settings. A low prevalence of 0.03\u0026ndash;0.09% in major general outpatient clinics in Benin or DRC implies that RVO is a small percentage of a broad spectrum of patients with various eye diseases, whereas retina specialist clinics had 7\u0026ndash;10% of their patients with RVO, indicating significant importance of RVO among other severe retinal pathologies, including diabetic retinopathy, a major public health issue, or age-related macular degeneration(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eOne of the observed consistent results is that there is a strong link that was noticed between RVO and systemic vascular risk factors such as hypertension and diabetes mellitus. It was found that more than half of the patients with RVO were suffering from hypertension in almost all the studies that were reviewed(\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). This is important since it establishes that it is the key modifiable risk factor for SSA. Due to low levels of both patient and physician hypertension awareness and poor rates of hypertension control in the Africa region, it is possible that RVO could be a sentinel presentation of systemic vascular disease. Almost one-fourth to almost half of patients with RVO were found to be suffering from diabetes mellitus(\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eGlaucoma showed the most frequent association with RVO as comorbidity, occurring in up to one-fourth of patients with CRVO. This association is of great significance in SSA, where primary open-angle glaucoma is found to be highly prevalent, with many of these cases being undiagnosed. Against this background, intraocular pressure could potentially predispose patients to CRVO due to poor venous drainage, while ischemic CRVO could progress to neovascular glaucoma, signifying a bidirectional relationship. Specialists in SSA, who practice multiple specializations owing to manpower shortages, should remain alert for a simultaneous association of glaucoma with RVO or RVO with glaucoma(\u003cspan additionalcitationids=\"CR16\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAn interesting additional finding is the relative preponderance of CRVO over BRVO observed in some of the African studies, in contrast to what is observed in population-based studies in developed countries, in which BRVO is generally more frequent. No doubt this is a reflection of referral patterns, since CRVO tends to produce more severe vision loss(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). That this is true is suggested by the finding in the DRC study that indeed found BRVO to predominate, as would be expected. The age of presentation of RVO in SSA seems to be slightly younger than that of Western civilization, with mean ages of 60 years or slightly younger.\u003c/p\u003e \u003cp\u003eThis could be related to demographics, the onset of poorly controlled hypertension, or survivorship bias. Nevertheless, it means that one should not view RVO as being predominantly a condition of older people in SSA, since the middle-aged with vascular risk factors contribute to the pool of patients suffering from RVO. The clinical outcomes were poor, with many patients presenting with severe visual impairment or blindness. There were high levels of macular edema, neovascularization, and neovascular glaucoma, suggesting late presentation and poor access to care.\u003c/p\u003e \u003cp\u003eWhile some of the tertiary centers mentioned the use of photocoagulation therapy and intravitreal therapy, the availability of anti-VEGF therapy is still imperfect(\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e). Firstly, from the public health point of view, these results illustrate the escalating importance of RVO in SSA with the recent increases in NCDs. Improving hypertension and diabetic care could also alleviate the number of RVO and other vascular forms of blindness. Programs for the visually impaired, historically driven by cataract and infectious causes of blindness, could increasingly turn their attention to retinal vascular diseases.\u003c/p\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eSTRENGTHS AND LIMITATIONS\u003c/h2\u003e \u003cp\u003eThis is the first combined analysis of the prevalence and characteristics of retinal vein occlusion (RVO) in Sub-Saharan Africa (SSA), integrating new information from a number of countries. Application of strict methods for data analysis using random effects preserves the integrity of the study findings. Thorough selection of data for the subtypes of RVO made it possible to discuss the findings at the regional level.\u003c/p\u003e \u003cp\u003eHowever, certain limitations must be acknowledged. Firstly, all the studies were hospitalized, which decreases the ability to generalize the findings for the whole population. Additionally, the number of studies was limited, which decreased the possibility of conducting subgroup analysis, with significant heterogeneity that reduced the confidence in the pooled analysis. Moreover, there was a variability in reporting risk factors, with limited information on the role of smoking, lipid disorders, among other risk factors. Lastly, the absence of population studies, together with limited data on treatment outcomes, reveals areas of research that should be explored.\u003c/p\u003e \u003cp\u003eThese factors notwithstanding, this literature review is significant for establishing a benchmark to comprehend RVO in the context of SSA and the importance of both population-based research, surveillance, and systematic as well as ocular care.\u003c/p\u003e \u003c/div\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eIn conclusion, retinal vein occlusion is a recognized but rare form of retinopathy in Sub-Saharan Africa with a prevalence of about one percent or lower among patients seeking care for their eyes. This data suggests that retinal vein occlusions in SSA occur more among middle-aged to older patients, who predominantly present with associated systemic hypertension, followed by diabetes mellitus, which is consistent with risk factors for globally encountered retinal vein occlusions. Of significance is that, relative to the other clinical practices mentioned, it would appear that the frequency of retinal vein occlusions related to the center of the retina is at least as great, or perhaps more common, than that of the branches\u0026mdash;a reflection of severity likely driving patient attendance. Such marked variability of prevalence rates strongly suggests that the burden of retinal vein occlusions is likely to vary from rare in a general clinic to a significant proportion of patients in a retina practice.\u003c/p\u003e \u003cp\u003eThe meta-analysis draws attention to the need for care coordination: the care of RVO patients in Africa must incorporate risk factors for cardiovascular diseases, whereas the management of systemic diseases could potentially alleviate retinal complications like RVO. Focusing on public health issues, since the epidemiologic transition in Africa is progressing into a phase with more emphasis on non-communicable diseases,\u003c/p\u003e \u003cp\u003eRVO would potentially become more recognized in the region and would need more attention. Prospective epidemiologic studies would be important in determining the true incidence of RVO in the community, and treatment must be made widely available to prevent blindness among those with RVO. Conclusion\u003c/p\u003e \u003cp\u003eWhile RVO is not one of the major causes of blindness in SSA at present, it still remains a significant contributing factor to blindness in the older population and is a reflection of poor systemic health. It is important to note that improving these systemic risk factors would provide a two-fold gain for both general and eye health. It is suggested that the service delivery for ophthalmology in Africa needs to improve the patient work-up for RVO patients systemically by integrating with other specialists to provide a collective treatment plan for RVO patients. This would help SSA adequately confront the growing burden of retinal vascular diseases in the senior members of their communities.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable, as this study is based solely on analysis of previously published data and does not involve any human participants or identifiable individual data.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and resources.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analyzed throughout this study are contained in this published article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors have no competing interests to declare.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study did not get any particular financial support from public, commercial, or non-profit funding agencies.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors' contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDr.Mohamed Farah Ismail conceived and planned the study, conducted the literature search, executed data extraction, conducted statistical analysis, and prepared the manuscript. Prof. Intisar Khalafalla critically reviewed the methodology, validated the data, and revised manuscripts. All authors read and approved the final manuscript. Acknowledgments The authors appreciate the support from the Department of Ophthalmology, Kampala International University Teaching Hospital.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAdenuga OO, Ramyil AV, Odugbo OP, Oyediji FJ. PREVALENCE, PATTERN AND RISK FACTORS FOR RETINAL VASCULAR OCCLUSIONS IN A TERTIARY HOSPITAL IN JOS, NIGERIA. Niger J Med J Natl Assoc Resid Dr Niger. 2015;24(4):331\u0026ndash;6. \u003c/li\u003e\n\u003cli\u003eUhumwangho O, Oronsaye D. Retinal vein occlusion in Benin City, Nigeria. Niger J Surg. 2016;22(1):17. \u003c/li\u003e\n\u003cli\u003eRogers S, McIntosh RL, Cheung N, Lim L, Wang JJ, Mitchell P, et al. The Prevalence of Retinal Vein Occlusion: Pooled Data from Population Studies from the United States, Europe, Asia, and Australia. Ophthalmology. 2010 Feb;117(2):313-319.e1. \u003c/li\u003e\n\u003cli\u003eKolar P. Risk factors for central and branch retinal vein occlusion: a meta-analysis of published clinical data. J Ophthalmol. 2014;2014:724780. \u003c/li\u003e\n\u003cli\u003eOdoulami L, Savage Y, Alamou S, Sounouvou I, Tchabi S, Doutetien C. Retinal vein occlusion in Cotonou. Austin J Clin Ophthalmol. 2018;5:1091. \u003c/li\u003e\n\u003cli\u003eFiebai B, Ejimadu C, Komolafe R. Incidence and risk factors for retinal vein occlusion at the University of Port Harcourt Teaching Hospital, Port Harcourt, Nigeria. Niger J Clin Pract. 2014;17(4):462. \u003c/li\u003e\n\u003cli\u003eAdenuga OO, Ramyil AV, Odugbo OP, Oyediji FJ. Prevalence, pattern and risk factors for retinal vascular occlusions in a tertiary hospital in Jos, Nigeria. Niger J Med. 2015;24(4):331\u0026ndash;6. \u003c/li\u003e\n\u003cli\u003eRogers S, McIntosh RL, Cheung N, Lim L, Wang JJ, Mitchell P, et al. The prevalence of retinal vein occlusion: pooled data from population studies from the United States, Europe, Asia, and Australia. Ophthalmology. 2010;117(2):313\u0026ndash;9. \u003c/li\u003e\n\u003cli\u003eKolar P. Risk factors for central and branch retinal vein occlusion: a meta‐analysis of published clinical data. J Ophthalmol. 2014;2014(1):724780. \u003c/li\u003e\n\u003cli\u003eOkonkwo ON, Adenuga OO, Nkanga D, Ovienria W, Ibanga A, Agweye CT, et al. Prevalence and Systemic Associations of Retinal Vascular Occlusions in Sub-Saharan Africa. Ann Afr Med. 2023 July;22(3):279\u0026ndash;85. \u003c/li\u003e\n\u003cli\u003eSingh G, Pillai S. Demographic profile, prevalence, pattern, and risk factors for retinal vein occlusion in Liberia: A retrospective study. Oman J Ophthalmol. 2024;17(2):205\u0026ndash;9. \u003c/li\u003e\n\u003cli\u003eKoki G, Yaya G, Ep\u0026eacute;e E, Bilong Y, Noa G, Helles G, et al. Epid\u0026eacute;miologie et clinique des occlusions veineuses r\u0026eacute;tiniennes en milieu hospitalier camerounais. Health Sci Dis. 2018;19(1). \u003c/li\u003e\n\u003cli\u003eJoseph KM, JP LW. Les occlusions veineuses r\u0026eacute;tiniennes: facteurs \u0026eacute;tiologiques et \u0026eacute;volutifs des patients suivis aux cliniques universitaires de Lubumbashi. Rev Afr M\u0026eacute;decine Sant\u0026eacute; Publique. 2025;8(1):228\u0026ndash;38. \u003c/li\u003e\n\u003cli\u003eAdeloye D, Abaa DQ, Owolabi EO, Ale BM, Mpazanje RG, Dewan MT, et al. Prevalence of hypercholesterolemia in Nigeria: a systematic review and meta-analysis. Public Health. 2020;178:167\u0026ndash;78. \u003c/li\u003e\n\u003cli\u003eThomas GN, Kiew SY, Singh P, Dmitriev P, Thomas AS, Fekrat S. Central retinal vein occlusion: the effect of antiplatelet and anticoagulant agents. J Vitreoretin Dis. 2022;6(2):97\u0026ndash;103. \u003c/li\u003e\n\u003cli\u003eHayreh SS. Retinal vein occlusion. Indian J Ophthalmol. 1994;42(3):109\u0026ndash;32. \u003c/li\u003e\n\u003cli\u003eOrth DH, Patz A. Retinal branch vein occlusion. Surv Ophthalmol. 1978;22(6):357\u0026ndash;76. \u003c/li\u003e\n\u003cli\u003eDaien V, Eldem BM, Talks JS, Korobelnik JF, Mitchell P, Finger RP, et al. Real-world data in retinal diseases treated with anti-vascular endothelial growth factor (anti-VEGF) therapy\u0026ndash;a systematic approach to identify and characterize data sources. BMC Ophthalmol. 2019;19(1):206. \u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"retinal vein occlusion, Africa, prevalence, meta-analysis, hypertension, branch retinal vein occlusion, central retinal vein occlusion, risk factors","lastPublishedDoi":"10.21203/rs.3.rs-8388967/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8388967/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e Retinal vein occlusion (RVO) is a very common retinal vascular disorder and a significant cause of visual loss worldwide. However, the burden, proportion of subtypes, and risk factors associated with RVO in Sub-Saharan Africa (SSA) remain poorly explored and undefined. This systematic review and meta-analysis were conducted to assess the prevalence of RVO in Sub-Saharan Africa and its subtypes, risk factors, and presentation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e: A systematic search was conducted on PubMed/MEDLINE, African Journals Online, and Google Scholar for observational studies featuring RVO prevalence data published since January 2000 until October 2025. Selection of observational studies was performed in accordance with the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement 2020. Random-effects meta-analysis methods were used in obtaining prevalence rates, with heterogeneity tested with Cochran’s Q test and degree of heterogeneity determined with I² statistics. Funnel plots and regression test through Egger’s test were done to test publication bias.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u0026nbsp;\u003c/strong\u003eEight studies from five SSA countries (Nigeria, Liberia, Cameroon, Democratic Republic of Congo, and Benin) with a cumulative total of 158,940 participants were found to satisfy the criteria. RVO prevalence varied from 0.03% in general ophthalmology clinics to 10.8% among tertiary referral centers for retinal diseases. Overall,\u003c/p\u003e\n\u003cp\u003eThe Pooled prevalence of RVO among SSA countries was found to be \u003cstrong\u003e0.8% (95% CI = 0.2%–3.1%)\u003c/strong\u003e, with a degree of heterogeneity of 97.9% (p \u0026lt; 0.001\u003c/p\u003e\n\u003cp\u003eCentral retinal vein occlusion (CRVO) was common in studies from \u003cstrong\u003eNigeria (58% - 74%),\u003c/strong\u003e \u003cstrong\u003eLiberia (60%), and Cameroon (55%)\u003c/strong\u003e, while branch retinal vein occlusion (BRVO) was found more frequently in \u003cstrong\u003eDemocratic Republic of Congo (69.2%).\u003c/strong\u003e \u003cstrong\u003eBenin reported almost equal incidents of CRVO and BRVO (50% each).\u003c/strong\u003e The prevalent risk factor was systemic \u003cstrong\u003ehypertension,\u003c/strong\u003efollowed by \u003cstrong\u003ediabetes mellitus\u003c/strong\u003e, while \u003cstrong\u003eglaucoma \u003c/strong\u003ewas identified as the dominant eye complication. Visual acuities at presentation were poor in all studies.\u003c/p\u003e\n\u003cp\u003eThere was no evidence of publication bias (Egger's test, p ≈ 0.20).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e: \u0026nbsp;RVO is rare in general ophthalmic referrals in SSA but presents an important proportion in retina referrals. RVO demonstrates distinct links with systemic vascular risk factors, thus emphasizing the importance of comprehensive cardiovascular and ophthalmological management, as well as population-based epidemiological studies, in SSA.\u003c/p\u003e","manuscriptTitle":"Retinal Vein Occlusion in Sub Saharan Africa: A Systematic Review and Meta-analysis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-16 14:14:04","doi":"10.21203/rs.3.rs-8388967/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"799dc1e3-2b42-4327-964c-f28a3df8424e","owner":[],"postedDate":"January 16th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-03-10T08:12:13+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-16 14:14:04","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8388967","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8388967","identity":"rs-8388967","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}