Comparison of Clinical Outcomes Between Implantable Collamer Lens Implantation and Photorefractive Keratectomy for Myopic Regression After Laser Vision Correction

Comparison of Clinical Outcomes Between Implantable Collamer Lens Implantation and Photorefractive Keratectomy for Myopic Regression After Laser Vision Correction | 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 Comparison of Clinical Outcomes Between Implantable Collamer Lens Implantation and Photorefractive Keratectomy for Myopic Regression After Laser Vision Correction Bu Ki Kim, Young Taek Chung This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9026883/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract Background : Myopic regression is a common complication after laser vision correction (LVC). While photorefractive keratectomy (PRK) and implantable collamer lens (ICL) implantation are considered effective retreatment options with favorable outcomes, no direct comparative study has evaluated these two modalities for treating regression. Therefore, we aimed to compare the clinical outcomes and astigmatic correction patterns of ICL implantation and PRK in patients with myopic regression after LVC. Methods : This retrospective study compared 30 eyes treated with ICL implantation and 24 eyes with transepithelial PRK as retreatment for myopic regression after prior LVC. Clinical outcomes, including visual acuity, refractive stability, and vector analysis of astigmatic correction, were evaluated over a 6-month follow-up period. Results : At 6 months, 100% of eyes in the ICL group and 92% in the PRK group achieved a postoperative spherical equivalent (SE) within ±1.00 D, with uncorrected distance visual acuity (UDVA) of 20/20 or better observed in 100% and 96% of eyes, respectively. The ICL group showed faster early visual recovery with significantly better UDVA at 1 week and 1 month ( P < 0.001 and P = 0.005), although long-term outcomes at 6 months were comparable between the groups. The ICL group exhibited superior refractive stability, with no significant change in SE over 6 months ( P = 0.095), whereas the PRK group showed a significant change ( P = 0.040). Vector analysis revealed a tendency toward undercorrection in the ICL group (mean correction index: 0.80 ± 0.45) and overcorrection in the PRK group (1.09 ± 0.55), with the PRK group showing significantly greater surgically induced astigmatism ( P = 0.045). No vision-threatening complications occurred in either group. Conclusions : Both ICL implantation and PRK are safe and effective retreatment options for myopic regression after LVC. ICL demonstrated faster early visual recovery and greater refractive stability, while PRK showed higher astigmatic correction with a trend toward overcorrection. ICL myopic regression PRK retreatment Figures Figure 1 Figure 2 INTRODUCTION Myopic regression is a common complication following laser vision correction (LVC), including photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK) [ 1 ]. At least 28% of patients undergoing refractive surgery still experience myopic regression, with retreatment rates due to regression reported to range from 1.8% to 22% [ 2 , 3 ]. Retreatment options after LVC for myopic regression include PRK, LASIK, and implantable collamer lens (ICL) implantation [ 4 ]. Due to the increased susceptibility to flap-related complications, diffuse lamellar keratitis, and potential corneal ectasia, LASIK is generally considered less favorable as a retreatment modality [ 5 – 7 ]. PRK and ICL implantation, on the other hand, have been associated with favorable outcomes and are commonly considered effective approaches for retreatment, with recent studies supporting their safety and efficacy with promising outcomes [ 3 , 4 ]. However, to date, no direct comparative study exists between ICL implantation and PRK for the treatment of myopic regression following LVC. Therefore, we aimed to evaluate and compare the clinical outcomes and astigmatic correction patterns of these two surgical options. METHODS Study Participants This was a retrospective, comparative study that included patients with myopic regression after LASIK or PRK who underwent PRK or ICL implantation at the Onnuri Smile Eye Clinic, Seoul, Republic of Korea, between August 2016 and October 2024. The study protocol was approved by the Public Internal Regulatory Board of the Ministry of Health and Welfare, Republic of Korea (P01-202601-01-036). This study was conducted in accordance with the tenets of the Declaration of Helsinki. The requirement for informed consent was waived by the board due to the retrospective nature of the study. Patients underwent ICL implantation (ICL group) or PRK (PRK group) as retreatment for myopic regression. The selection of the retreatment method was based on preoperative corneal status and individual patient needs. Inclusion criteria were a stable refractive status for at least 1 year, a preoperative corrected distance visual acuity (CDVA) of 20/30 or better, and no sign of corneal ectasia on at least three consecutive corneal tomographic evaluations. Patients with any ocular surface disease, history of ocular trauma, glaucoma, or cataract were excluded. In the ICL group, eyes with an endothelial cell density of less than 2,000 cells/mm² or an anterior chamber depth from the endothelium of less than 2.8 mm were excluded. In the PRK group, eyes with an estimated residual stromal thickness of 300 µm or less after retreatment were also excluded. Clinical records were included in the analysis if the patients had completed a 6-month postoperative follow-up assessment. Follow-up visits were scheduled at 1 week, 1 month, 3 months, and 6 months postoperatively to monitor clinical outcomes. Surgical procedure All surgeries were performed by two experienced surgeons (CYK and KBK). The target refraction was set to emmetropia for patients under 40 years of age, and to -0.50 D for those aged 40 years or older. In the ICL group, a 3.0 mm corneal incision was created on the steep axis of astigmatism as determined by preoperative manifest refraction, using the Callisto eye image-guided system (Carl Zeiss Meditec, Jena, Germany). A 1% sodium hyaluronate was injected into the anterior chamber, and the ICL was inserted through an injector cartridge. After positioning the ICL, the sodium hyaluronate was completely removed by manual irrigation. In cases with astigmatism greater than 0.75 D, an additional 3.0 mm incision was made on the cornea opposite to the same axis as the main incision. The spheric V4c or V5 model was used in all cases. ICL powers were calculated using a modified vertex formula provided by the manufacturer. Patients were instructed to use 0.5% moxifloxacin and 0.1% fluorometholone four times a day for a month. In the PRK group, the central corneal epithelial thickness was measured preoperatively using anterior segment optical coherence tomography (Cirrus HD-OCT, Carl Zeiss Meditec, Dublin, CA, USA), and epithelial ablation was performed using the PTK mode of the MEL 90 excimer laser system (Carl Zeiss Meditec, Jena, Germany), followed by stromal ablation using the PRK mode with the Triple-A profile. The optic zone ranged from 6.0 to 6.5 mm. After ablation, 0.02% Mitomycin C was applied to the stromal bed for 40 seconds and subsequently rinsed thoroughly with a balanced salt solution. At the end of the procedure, all eyes got a therapeutic contact lens for 4 days. Patients were instructed to use 0.5% moxifloxacin four times a day for a week and 0.1% fluorometholon six times a day for 1 week, four times a day for 2 weeks, and two times a day for another month. Statistical analysis Data are presented as mean ± standard deviation. IBM SPSS Statistics for Windows (v. 25.0, IBM Corporation) was used to perform statistical analyses. Data normality was confirmed using a Kolmogorov–Smirnov test. Comparisons between the two groups were performed using an independent sample t-test for normally distributed data and a Mann–Whitney U test for non-normally distributed data. Comparison of categorical variables was performed using a chi-squared test. The postoperative visual and refractive outcomes were compared using a repeated-measures analysis of variance test. For statistical analyses of visual acuity, the logarithm of the minimum angle of resolution (logMAR) was used. A vector analysis of astigmatic correction was performed using the Alpins method. P ≤ 0.05 was regarded as statistically significant. RESULTS A total of 30 eyes from 17 patients were included in the ICL group, and 24 eyes from 14 patients were included in the PRK group. No intraoperative or postoperative complication was detected. There was no significant difference between the two groups in terms of age, sex, laterality, preoperative uncorrected distance visual acuity (UDVA), CDVA, sphere, cylinder, spherical equivalent (SE), and type of previous LVC (Table 1). Table 2 presents the postoperative visual and refractive outcomes. The ICL group achieved faster early visual recovery compared to the PRK group. At 1 week and 1 month postoperatively, the ICL group demonstrated significantly better UDVA than the PRK group ( P < 0.001 and P = 0.005, respectively), while no significant differences were noted at 3 and 6 months. CDVA was also significantly better in the ICL group at 1 week ( P < 0.001), but the difference was not significant at later follow-ups. Regarding visual and refractive stability, within-group analysis revealed that the ICL group maintained stable UDVA ( P = 0.095) and SE ( P = 0.095) without significant change over 6 months. In contrast, the PRK group exhibited significant longitudinal changes in UDVA ( P < 0.001), CDVA ( P = 0.010), sphere ( P = 0.038), and SE ( P = 0.040), indicating a more consistent and stable postoperative course in the ICL group compared to the PRK group. The mean efficacy index (postoperative UDVA/preoperative CDVA) was 0.98 ± 0.15 and 0.94 ± 0.17 in the ICL and PRK groups, respectively ( P = 0.556). The mean safety index (postoperative CDVA/preoperative CDVA) was 1.00 ± 0.15 and 0.98 ± 0.12 in the ICL and PRK groups, respectively ( P = 0.823). Fig. 1 and Fig. 2 present the 6-month postoperative clinical outcomes of the ICL and PRK groups using the standard nine graphs. Postoperative UDVA of 20/20 or better was achieved in 100% and 96% of the ICL and PRK groups, respectively (Fig. 1a and Fig. 2a). In the comparison between preoperative and postoperative CDVA, 73% of eyes in the ICL group showed either no change or a gain of one line, and 27% experienced a loss of one line. No eyes in the ICL group had a loss of two or more lines. In the PRK group, 76% of eyes showed no change or a gain of one line, 21% had a loss of one line, and 4% experienced a loss of two or more lines (Fig. 1c and Fig. 2c). Postoperative SE was within ±0.50 D in 57% and within ±1.00 D in 100% of eyes in the ICL group, and within ±0.50 D in 67% and within ±1.00 D in 92% of eyes in the PRK group (Fig. 1e and Fig. 2e). However, in the comparison of attempted SE versus achieved SE, the regression slope in the ICL group was 1.0715, indicating a near-proportional relationship, whereas in the PRK group, the slope was 0.842, suggesting a tendency toward undercorrection in eyes with higher SE. The coefficient of determination ( R ²) was also higher in the ICL group (0.8855) compared to the PRK group (0.7625), indicating a better predictive correlation in the ICL group (Fig. 1d and Fig. 2d). Postoperative astigmatism of 0.50 D or less was achieved in 88% and 1.00 D or less in 96% of eyes in the ICL group, while in the PRK group, 0.50 D or less was achieved in 84% and 1.00 D or less in 100% of eyes (Fig. 1g and Fig. 2g). However, when comparing target induced astigmatism (TIA) versus surgically induced astigmatism (SIA), distinct trends were observed between the two groups. The ICL group exhibited a general tendency toward undercorrection, which became more pronounced as the TIA increased. This was reflected in the regression slope of 0.4968 with an R² value of 0.4429, indicating a moderate correlation (Fig. 1h). In contrast, the PRK group showed a pattern of overcorrection, although the degree of overcorrection diminished with increasing TIA. The regression slope in this group was 0.6145 with an R ² value of 0.368, also indicating a moderate correlation (Fig. 2h). Table 3 shows the results of the vector analysis. The SIA, representing the actual amount of astigmatism correction achieved, was 0.45 ± 0.31 D in the ICL group and 0.64 ± 0.47 D in the PRK group, with the PRK group showing a significantly higher SIA ( P = 0.045). The correction index (CI), defined as the ratio of SIA to TIA, was 0.80 ± 0.45 in the ICL group and 1.09 ± 0.55 in the PRK group. While the ICL group exhibited a trend toward undercorrection (CI 1). However, the intergroup difference in CI was not statistically significant ( P = 0.072). Similarly, the magnitude of error (ME), calculated as the difference between SIA and TIA, was -0.07 ± 0.31 D in the ICL group and 0.16 ± 0.41 D in the PRK group, showing a statistically significant difference ( P = 0.022). The negative ME in the ICL group indicates a tendency toward undercorrection, whereas the positive ME in the PRK group suggests a trend toward overcorrection. However, the absolute value of ME showed no statistically significant difference between the groups ( P = 0.896). No statistically significant differences were observed between the two groups in the difference vector, index of success, and angle of error. DISCUSSION In this retrospective comparative study, we evaluated the clinical outcomes of ICL implantation and PRK as retreatment options for myopic regression following LVC. Our findings indicate that while both procedures are safe and effective, ICL implantation provides distinct advantages in terms of early visual rehabilitation and longitudinal refractive stability. Specifically, the ICL group demonstrated significantly faster visual recovery within the first month and maintained a consistent refractive status without significant fluctuations throughout the 6-month follow-up, whereas the PRK group exhibited significant regression. Several previous studies have reported favorable outcomes of ICL implantation in eyes with myopic regression following LVC. For example, Chung et al. [ 4 ] demonstrated excellent short-term efficacy and predictability, with 93% of eyes attaining a postoperative SE within ± 0.50 D and 100% within ± 1.00 D at 3 months postoperatively, and an efficacy index of 1.11. Similarly, Zhang et al. [ 8 ] reported a 6-month efficacy index of 1.19, safety index of 1.26, and 100% predictability within ± 0.50 D, with all eyes achieving UDVA of 20/20 or better. In the present study, 57% of eyes achieved a postoperative SE within ± 0.50 D, and 100% were within ± 1.00 D, with an efficacy index of 0.98. This relatively lower efficacy and predictability may be attributed to the intentional 0.50 D undercorrection in patients over 40 years of age, who comprised 30% of our cohort. Chen et al. [ 9 ] also reported favorable outcomes in a long-term study of ICL implantation after LVC, with a mean follow-up of 39 months, although a mild trend toward myopic regression was observed, possibly due to axial elongation [ 10 , 11 ]. In contrast, our 6-month follow-up demonstrated stable postoperative SE, suggesting good short-term refractive stability. PRK retreatment has also been investigated for the management of myopic regression. Turad et al. [ 3 ] reported that 80% of eyes achieved UDVA of 20/20 or better and 100% achieved UDVA of 20/25 or better, with a mean postoperative SE of − 0.38 ± 0.57 D and 100% of eyes within ± 1.00 D. Similarly, Moshirfar et al. [ 12 ] reported favorable outcomes of PRK retreatment, with 100% of eyes within ± 1.00 D and 87% achieving UDVA of 20/20 or better, yielding a safety index and efficacy index of 0.99 and 1.03, respectively. In our study, the PRK group showed 92% of eyes within ± 1.00 D and 96% achieving UDVA of 20/20 or better, with a safety index of 0.98 and an efficacy index of 0.94. The slightly lower efficacy observed compared to previous studies may be attributed to the intentional undercorrection of 0.50 D performed, as in the ICL group, in 25% of eyes. Notably, no previous studies have directly compared ICL and PRK for the correction of myopic regression following LVC. Therefore, our study provides meaningful clinical insights by offering the first head-to-head comparative evaluation of these two retreatment modalities in a single-center setting with standardized surgical protocols. As described above, both the ICL and PRK groups demonstrated favorable clinical outcomes at 6 months, comparable to previously reported results. However, ICL was superior to PRK in terms of speed of visual recovery and refractive stability. This is likely attributable to the inherent differences in healing mechanisms, particularly the time-dependent epithelial remodeling required after PRK. Such a difference in early recovery profiles is somewhat expected, but its quantification in a comparative context adds practical value for surgical decision-making. In the analysis of the relationship between attempted and achieved SE at 6 months, the ICL group demonstrated a higher coefficient of determination ( R ² = 0.8855) compared to the PRK group ( R ² = 0.7625), indicating greater predictability in postoperative refractive outcomes with ICL. Vector analysis further revealed differing patterns of astigmatic correction between the groups: the ICL group tended toward undercorrection, whereas the PRK group exhibited mild overcorrection. The undercorrection observed in the ICL group is primarily attributable to the use of non-toric ICL models. In our study, non-toric ICLs were utilized for all eyes despite preoperative astigmatism reaching up to 1.50 D. This clinical decision was based on the expectation that residual astigmatism could be sufficiently managed through incisional techniques—specifically by placing the main incision on the steep axis and adding opposite corneal incisions for cases exceeding 0.75 D. Furthermore, economic feasibility was a significant consideration; many patients, having already invested in their initial LVC, favored the cost-effectiveness of non-toric ICLs combined with incisional management. Our approach aligns with the findings of Liu et al. [ 13 ], who reported that while steep-axis incisions improve correction in eyes with low astigmatism (≤ 1.25 D), the mean CI remained 0.84 ± 0.30, suggesting residual undercorrection even with optimized incision placement. Similarly, in our cohort, although incisional management was a practical and cost-effective alternative, the astigmatic correction remained suboptimal compared to the results typically achieved with toric lenses. This highlights a trade-off between cost-effectiveness and absolute refractive precision in the context of retreatment. Conversely, the PRK group showed a tendency toward astigmatic overcorrection, with a mean CI of 1.09 ± 0.55. A similar trend was reported by Sun et al. [ 14 ], who investigated transepithelial PRK in virgin eyes and attributed overcorrection to the use of fixed, predefined epithelial profiles. In our cohort, this effect was likely amplified by the irregular epithelial remodeling following the initial LVC. Furthermore, the altered laser ablation rate in the previously treated stroma may have contributed to this overcorrection. Following prior LVC, the corneal stroma undergoes biomechanical and biochemical changes, including variations in hydration and collagen density. Such alterations can lead to an unpredictable stromal response to the excimer laser, potentially resulting in a higher ablation rate during retreatment compared to virgin eyes. Therefore, the synergistic effect of standardized epithelial profiles and altered stromal characteristics likely predisposed the PRK group to the observed overcorrection. This underscores the potential benefit of personalized ablation strategies, such as topography-guided or epithelial mapping-assisted PRK, in post-LVC eyes with non-uniform corneal profiles. Actually, Zhou et al. [ 15 ] applied transepithelial, topography-guided, epithelial mapping–assisted PRK in eyes with residual myopic astigmatism after LVC, reporting improved precision with 100% of eyes within ± 1.00 D of the target. Several limitations must be considered when interpreting the results of this study. First, the retrospective design inherently introduces selection bias, as retreatment modality was not randomized but determined by preoperative parameters and surgeon discretion. Second, the sample size was relatively small, and although the results were statistically robust, larger-scale studies would enhance generalizability. Third, the follow-up duration was limited to 6 months; therefore, long-term complications, regression, or changes in visual acuity cannot be fully assessed. Fourth, all eyes in the ICL group received non-toric ICLs, which limits the generalizability of the astigmatism correction outcomes; use of toric ICLs may have yielded different refractive results. Additionally, subjective parameters such as patient satisfaction, quality of vision, or glare/halo perception were not evaluated but may be clinically meaningful in the context of retreatment. In conclusion, both ICL implantation and PRK were found to be effective and safe retreatment options for patients with myopic regression following prior LVC. While 6-month outcomes were comparable between the two modalities, ICL implantation demonstrated superior early visual recovery and faster refractive stability. Although both procedures achieved similar levels of postoperative astigmatism reduction, the patterns of correction differed, with ICL tending toward undercorrection and PRK toward overcorrection. These findings suggest that the choice between ICL and PRK should be carefully tailored to the patient's clinical profile and visual demands. Future prospective studies with larger cohorts, longer follow-up periods, additional patient-reported outcome measures, and objective assessments of visual quality are warranted to further validate these results. Declarations Acknowledgements Not applicable. Authors’ contributions Literature screening and selection were performed by BKK. BKK and YTC participated in the design of the study. BKK drafted the manuscript and carried out the statistical analysis. YTC interpreted the data. BKK and YTC prepare and review the manuscript. YTC has given final approval of the version to be published. All authors read and approved the final manuscript. Funding There were no funding sources for this study. Data availability The datasets analyzed during the current study are available from the corresponding author on reasonable request. Ethics approval and consent to participate The Public Internal Regulatory Board of the Ministry of Health and Welfare, Korea, approved this study (P01-202601-01-036). This research was conducted in accordance with the tenets of the Declaration of Helsinki. Informed consent was waived due to the retrospective design of the study. Consent for publication Not applicable. Competing interests The authors declare no competing interests. References Ramin S, Moallemi Rad L, Abbasi A, et al. Myopic regression after photorefractive keratectomy: a retrospective cohort study. Med Hypothesis Discov Innov Ophthalmol. 2019;8:299–305. Wang X, Zhao G, Lin J, Jiang N, Wang Q, Xu Q. Efficacy and safety of topical timolol eye drops in the treatment of myopic regression after laser in situ keratomileusis: a systematic review and meta-analysis. J Ophthalmol. 2015;2015:985071. Alkadi TA, Binyousef FH, Alruwaili SA. Transepithelial photorefractive keratectomy enhancement for myopic regression. Oman J Ophthalmol. 2025;18:138–43. Chung B, Kim JH, Kang DSY, et al. 3-month surgical outcomes of Implantable Collamer Lens implantation for myopic regression after laser vision correction surgeries: a retrospective case series. BMC Ophthalmol. 2021;21:397. Brahma A, McGhee CN, Craig JP, et al. Safety and predictability of laser in situ keratomileusis enhancement by flap reelevation in high myopia. J Cataract Refract Surg. 2001;27:593–603. Pérez-Santonja JJ, Ayala MJ, Sakla HF, Ruíz-Moreno JM, Alió JL. Retreatment after laser in situ keratomileusis. Ophthalmology. 1999;106:21–8. Sharma N, Balasubramanya R, Sinha R, Titiyal JS, Vajpayee RB. Retreatment of LASIK. J Refract Surg. 2006;22:396–401. Zhang J, He F, Liu Y, Fan X. Implantable collamer lens with a central hole for residual refractive error correction after corneal refractive surgery. Exp Ther Med. 2020;20:160. Chen X, Wang XY, Zhang X, Chen Z, Zhou XT. Implantable collamer lens for residual refractive error after corneal refractive surgery. Int J Ophthalmol. 2016;9:1421–6. Fotedar R, Mitchell P, Burlutsky G, Wang JJ. Relationship of 10-year change in refraction to nuclear cataract and axial length findings from an older population. Ophthalmology. 2008;115:1273–8. Saka N, Ohno-Matsui K, Shimada N, et al. Long-term changes in axial length in adult eyes with pathologic myopia. Am J Ophthalmol. 2010;150:562–8. Moshirfar M, Basharat NF, Kelkar N, Bundogji N, Ronquillo YC, Hoopes PC. Visual outcomes of photorefractive keratectomy enhancement after primary LASIK. J Refract Surg. 2022;38:733–40. Liu S, Liu J, Lin F, et al. Efficacy comparison between steep-meridian incision and non-steep-meridian incision in implantable collamer lens surgery with low-to-moderate astigmatism. Ophthalmol Ther. 2023;12:1711–22. Sun L, Jhanji V, Li S, et al. Vector analysis of astigmatic correction after single-step transepithelial photorefractive keratectomy and femtosecond-assisted laser in-situ keratomileusis for low to moderate myopic astigmatism. Indian J Ophthalmol. 2022;70:3483–9. Zhou W, Reinstein DZ, Chen X, et al. Transepithelial topography-guided ablation assisted by epithelial thickness mapping for treatment of regression after myopic refractive surgery. J Refract Surg. 2019;35:525–33. Tables Table 1 to 3 are available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files tables.docx Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 14 Apr, 2026 Reviewers agreed at journal 09 Apr, 2026 Reviewers invited by journal 02 Apr, 2026 Editor invited by journal 05 Mar, 2026 Editor assigned by journal 05 Mar, 2026 Submission checks completed at journal 05 Mar, 2026 First submitted to journal 04 Mar, 2026 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-9026883","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":617434612,"identity":"bfd670f8-46e6-4826-8438-064afd34899f","order_by":0,"name":"Bu Ki Kim","email":"","orcid":"","institution":"Onnuri Smile Eye Clinic","correspondingAuthor":false,"prefix":"","firstName":"Bu","middleName":"Ki","lastName":"Kim","suffix":""},{"id":617434613,"identity":"0988116f-3083-4eae-8e01-c61ac2d0da7a","order_by":1,"name":"Young Taek Chung","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAv0lEQVRIiWNgGAWjYHACNjDJz5BAvAaIFskGqBYeorUYHCBWi8H95mePeXfUyhsfT34mdYPhjpw9QS3H2MyNec8cN9x25pmZdA7DM2PCthzjYZPmbTuWYHYjAaTlcGIP0VqMZ6R/A2mpJ1ZLTYKBRA7YlgSCDpM8lmYmObftgOGMM2+KrXMMDhv2HCCghe/w4WcSb9vq5Pnb0zfezqk4LM/eQECLAsTMwzB3EnIVEMhDzKwjQukoGAWjYBSMWAAARxw8xlOo5SwAAAAASUVORK5CYII=","orcid":"","institution":"Onnuri Eye Hospital","correspondingAuthor":true,"prefix":"","firstName":"Young","middleName":"Taek","lastName":"Chung","suffix":""}],"badges":[],"createdAt":"2026-03-04 07:09:47","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9026883/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9026883/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":106404708,"identity":"e222c060-9b04-4199-aad6-efecd558b1da","added_by":"auto","created_at":"2026-04-08 09:16:37","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":90328,"visible":true,"origin":"","legend":"\u003cp\u003eNine standard graphs for ICL implantation for correcting myopic regression after LVC showing the visual and refractive outcomes at 6 months postoperatively. (a) Preoperative CDVA and postoperative UDVA, (b) UDVA vs. CDVA, (c) Change in CDVA, (d) SEQ attempted vs. achieved, (e) SEQ accuracy, (f) SEQ stability, (g) Refractive astigmatism, (h) TIA vs. SIA, (i) Refractive astigmatism angle of error. ICL = implantable collamer lens; LVC = laser vision correction; Postop = postoperative; UDVA = uncorrected distance visual acuity; Preop = preoperative; CDVA = corrected distance visual acuity; SEQ = spherical equivalent refraction; D = diopters; SD = standard deviation; TIA = target induced astigmatism; SIA = surgically induced astigmatism; Arith = arithmetic; Abs = absolute.\u003c/p\u003e","description":"","filename":"Online1.png","url":"https://assets-eu.researchsquare.com/files/rs-9026883/v1/1757fca6f4e20f188bcd53f6.png"},{"id":106382657,"identity":"2d7e3599-435a-476b-87ad-4943ce752237","added_by":"auto","created_at":"2026-04-08 05:29:13","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":98443,"visible":true,"origin":"","legend":"\u003cp\u003eNine standard graphs for PRK for correcting myopic regression after LVC showing the visual and refractive outcomes at 6 months postoperatively. (a) Preoperative CDVA and postoperative UDVA, (b) UDVA vs. CDVA, (c) Change in CDVA, (d) SEQ attempted vs. achieved, (e) SEQ accuracy, (f) SEQ stability, (g) Refractive astigmatism, (h) TIA vs. SIA, (i) Refractive astigmatism angle of error. PRK = photorefractive keratectomy; LVC = laser vision correction; Postop = postoperative; UDVA = uncorrected distance visual acuity; Preop = preoperative; CDVA = corrected distance visual acuity; SEQ = spherical equivalent refraction; D = diopters; SD = standard deviation; TIA = target induced astigmatism; SIA = surgically induced astigmatism; Arith = arithmetic; Abs = absolute.\u003c/p\u003e","description":"","filename":"Online2.png","url":"https://assets-eu.researchsquare.com/files/rs-9026883/v1/1adacae2dd920bc4321e2e59.png"},{"id":107868692,"identity":"a390e8e3-a1a8-4fa6-9888-0a761b790c69","added_by":"auto","created_at":"2026-04-27 07:31:47","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":485455,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9026883/v1/e439d565-6f98-44a2-8431-d6082c2d7b78.pdf"},{"id":106382655,"identity":"3253c599-fcff-4ae5-8083-547063b0bc9b","added_by":"auto","created_at":"2026-04-08 05:29:12","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":29483,"visible":true,"origin":"","legend":"","description":"","filename":"tables.docx","url":"https://assets-eu.researchsquare.com/files/rs-9026883/v1/716ebb7b24bb60490665a725.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Comparison of Clinical Outcomes Between Implantable Collamer Lens Implantation and Photorefractive Keratectomy for Myopic Regression After Laser Vision Correction","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eMyopic regression is a common complication following laser vision correction (LVC), including photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK) [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. At least 28% of patients undergoing refractive surgery still experience myopic regression, with retreatment rates due to regression reported to range from 1.8% to 22% [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eRetreatment options after LVC for myopic regression include PRK, LASIK, and implantable collamer lens (ICL) implantation [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Due to the increased susceptibility to flap-related complications, diffuse lamellar keratitis, and potential corneal ectasia, LASIK is generally considered less favorable as a retreatment modality [\u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. PRK and ICL implantation, on the other hand, have been associated with favorable outcomes and are commonly considered effective approaches for retreatment, with recent studies supporting their safety and efficacy with promising outcomes [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. However, to date, no direct comparative study exists between ICL implantation and PRK for the treatment of myopic regression following LVC. Therefore, we aimed to evaluate and compare the clinical outcomes and astigmatic correction patterns of these two surgical options.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Participants\u003c/h2\u003e \u003cp\u003eThis was a retrospective, comparative study that included patients with myopic regression after LASIK or PRK who underwent PRK or ICL implantation at the Onnuri Smile Eye Clinic, Seoul, Republic of Korea, between August 2016 and October 2024. The study protocol was approved by the Public Internal Regulatory Board of the Ministry of Health and Welfare, Republic of Korea (P01-202601-01-036). This study was conducted in accordance with the tenets of the Declaration of Helsinki. The requirement for informed consent was waived by the board due to the retrospective nature of the study.\u003c/p\u003e \u003cp\u003ePatients underwent ICL implantation (ICL group) or PRK (PRK group) as retreatment for myopic regression. The selection of the retreatment method was based on preoperative corneal status and individual patient needs. Inclusion criteria were a stable refractive status for at least 1 year, a preoperative corrected distance visual acuity (CDVA) of 20/30 or better, and no sign of corneal ectasia on at least three consecutive corneal tomographic evaluations. Patients with any ocular surface disease, history of ocular trauma, glaucoma, or cataract were excluded. In the ICL group, eyes with an endothelial cell density of less than 2,000 cells/mm\u0026sup2; or an anterior chamber depth from the endothelium of less than 2.8 mm were excluded. In the PRK group, eyes with an estimated residual stromal thickness of 300 \u0026micro;m or less after retreatment were also excluded. Clinical records were included in the analysis if the patients had completed a 6-month postoperative follow-up assessment. Follow-up visits were scheduled at 1 week, 1 month, 3 months, and 6 months postoperatively to monitor clinical outcomes.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSurgical procedure\u003c/h3\u003e\n\u003cp\u003eAll surgeries were performed by two experienced surgeons (CYK and KBK). The target refraction was set to emmetropia for patients under 40 years of age, and to -0.50 D for those aged 40 years or older.\u003c/p\u003e \u003cp\u003eIn the ICL group, a 3.0 mm corneal incision was created on the steep axis of astigmatism as determined by preoperative manifest refraction, using the Callisto eye image-guided system (Carl Zeiss Meditec, Jena, Germany). A 1% sodium hyaluronate was injected into the anterior chamber, and the ICL was inserted through an injector cartridge. After positioning the ICL, the sodium hyaluronate was completely removed by manual irrigation. In cases with astigmatism greater than 0.75 D, an additional 3.0 mm incision was made on the cornea opposite to the same axis as the main incision. The spheric V4c or V5 model was used in all cases. ICL powers were calculated using a modified vertex formula provided by the manufacturer. Patients were instructed to use 0.5% moxifloxacin and 0.1% fluorometholone four times a day for a month.\u003c/p\u003e \u003cp\u003eIn the PRK group, the central corneal epithelial thickness was measured preoperatively using anterior segment optical coherence tomography (Cirrus HD-OCT, Carl Zeiss Meditec, Dublin, CA, USA), and epithelial ablation was performed using the PTK mode of the MEL 90 excimer laser system (Carl Zeiss Meditec, Jena, Germany), followed by stromal ablation using the PRK mode with the Triple-A profile. The optic zone ranged from 6.0 to 6.5 mm. After ablation, 0.02% Mitomycin C was applied to the stromal bed for 40 seconds and subsequently rinsed thoroughly with a balanced salt solution. At the end of the procedure, all eyes got a therapeutic contact lens for 4 days. Patients were instructed to use 0.5% moxifloxacin four times a day for a week and 0.1% fluorometholon six times a day for 1 week, four times a day for 2 weeks, and two times a day for another month.\u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eData are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation. IBM SPSS Statistics for Windows (v. 25.0, IBM Corporation) was used to perform statistical analyses. Data normality was confirmed using a Kolmogorov\u0026ndash;Smirnov test. Comparisons between the two groups were performed using an independent sample t-test for normally distributed data and a Mann\u0026ndash;Whitney U test for non-normally distributed data. Comparison of categorical variables was performed using a chi-squared test. The postoperative visual and refractive outcomes were compared using a repeated-measures analysis of variance test. For statistical analyses of visual acuity, the logarithm of the minimum angle of resolution (logMAR) was used. A vector analysis of astigmatic correction was performed using the Alpins method. \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026le;\u0026thinsp;0.05 was regarded as statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS","content":"\u003cp\u003eA total of 30 eyes from 17 patients were included in the ICL group, and 24 eyes from 14 patients were included in the PRK group. No intraoperative or postoperative complication was detected. There was no significant difference between the two groups in terms of age, sex, laterality, preoperative uncorrected distance visual acuity (UDVA), CDVA, sphere, cylinder, spherical equivalent (SE), and type of previous LVC (Table 1).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 2 presents the postoperative visual and refractive outcomes. The ICL group achieved faster early visual recovery compared to the PRK group. At 1 week and 1 month postoperatively, the ICL group demonstrated significantly better UDVA than the PRK group (\u003cem\u003eP\u0026nbsp;\u003c/em\u003e\u0026lt; 0.001 and \u003cem\u003eP\u003c/em\u003e = 0.005, respectively), while no significant differences were noted at 3 and 6 months. CDVA was also significantly better in the ICL group at 1 week (\u003cem\u003eP\u003c/em\u003e \u0026lt; 0.001), but the difference was not significant at later follow-ups. Regarding visual and refractive stability, within-group analysis revealed that the ICL group maintained stable UDVA (\u003cem\u003eP\u003c/em\u003e = 0.095) and SE (\u003cem\u003eP\u003c/em\u003e = 0.095) without significant change over 6 months. In contrast, the PRK group exhibited significant longitudinal changes in UDVA (\u003cem\u003eP\u003c/em\u003e \u0026lt; 0.001), CDVA (\u003cem\u003eP\u003c/em\u003e = 0.010), sphere (\u003cem\u003eP\u003c/em\u003e = 0.038), and SE (\u003cem\u003eP\u003c/em\u003e = 0.040), indicating a more consistent and stable postoperative course in the ICL group compared to the PRK group.\u003c/p\u003e\n\u003cp\u003eThe mean efficacy index (postoperative UDVA/preoperative CDVA) was 0.98 \u0026plusmn; 0.15 and 0.94 \u0026plusmn; 0.17 in the ICL and PRK groups, respectively (\u003cem\u003eP\u003c/em\u003e = 0.556). The mean safety index (postoperative CDVA/preoperative CDVA) was 1.00 \u0026plusmn; 0.15 and 0.98 \u0026plusmn; 0.12 in the ICL and PRK groups, respectively (\u003cem\u003eP\u003c/em\u003e = 0.823).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFig. 1 and Fig. 2 present the 6-month postoperative clinical outcomes of the ICL and PRK groups using the standard nine graphs. Postoperative UDVA of 20/20 or better was achieved in 100% and 96% of the ICL and PRK groups, respectively (Fig. 1a and Fig. 2a). In the comparison between preoperative and postoperative CDVA, 73% of eyes in the ICL group showed either no change or a gain of one line, and 27% experienced a loss of one line. No eyes in the ICL group had a loss of two or more lines. In the PRK group, 76% of eyes showed no change or a gain of one line, 21% had a loss of one line, and 4% experienced a loss of two or more lines (Fig. 1c and Fig. 2c). Postoperative SE was within \u0026plusmn;0.50 D in 57% and within \u0026plusmn;1.00 D in 100% of eyes in the ICL group, and within \u0026plusmn;0.50 D in 67% and within \u0026plusmn;1.00 D in 92% of eyes in the PRK group (Fig. 1e and Fig. 2e). However, in the comparison of attempted SE versus achieved SE, the regression slope in the ICL group was 1.0715, indicating a near-proportional relationship, whereas in the PRK group, the slope was 0.842, suggesting a tendency toward undercorrection in eyes with higher SE. The coefficient of determination (\u003cem\u003eR\u003c/em\u003e\u0026sup2;) was also higher in the ICL group (0.8855) compared to the PRK group (0.7625), indicating a better predictive correlation in the ICL group (Fig. 1d and Fig. 2d). Postoperative astigmatism of 0.50 D or less was achieved in 88% and 1.00 D or less in 96% of eyes in the ICL group, while in the PRK group, 0.50 D or less was achieved in 84% and 1.00 D or less in 100% of eyes (Fig. 1g and Fig. 2g). However, when comparing target induced astigmatism (TIA) versus surgically induced astigmatism (SIA), distinct trends were observed between the two groups. The ICL group exhibited a general tendency toward undercorrection, which became more pronounced as the TIA increased. This was reflected in the regression slope of 0.4968 with an R\u0026sup2; value of 0.4429, indicating a moderate correlation (Fig. 1h). In contrast, the PRK group showed a pattern of overcorrection, although the degree of overcorrection diminished with increasing TIA. The regression slope in this group was 0.6145 with an \u003cem\u003eR\u003c/em\u003e\u0026sup2; value of 0.368, also indicating a moderate correlation (Fig. 2h).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 3 shows the results of the vector analysis. The SIA, representing the actual amount of astigmatism correction achieved, was 0.45 \u0026plusmn; 0.31 D in the ICL group and 0.64 \u0026plusmn; 0.47 D in the PRK group, with the PRK group showing a significantly higher SIA (\u003cem\u003eP\u003c/em\u003e = 0.045). The correction index (CI), defined as the ratio of SIA to TIA, was 0.80 \u0026plusmn; 0.45 in the ICL group and 1.09 \u0026plusmn; 0.55 in the PRK group. While the ICL group exhibited a trend toward undercorrection (CI \u0026lt; 1), the PRK group showed a tendency for overcorrection (CI \u0026gt; 1). However, the intergroup difference in CI was not statistically significant (\u003cem\u003eP\u003c/em\u003e = 0.072). Similarly, the magnitude of error (ME), calculated as the difference between SIA and TIA, was -0.07 \u0026plusmn; 0.31 D in the ICL group and 0.16 \u0026plusmn; 0.41 D in the PRK group, showing a statistically significant difference (\u003cem\u003eP\u003c/em\u003e = 0.022). The negative ME in the ICL group indicates a tendency toward undercorrection, whereas the positive ME in the PRK group suggests a trend toward overcorrection. However, the absolute value of ME showed no statistically significant difference between the groups (\u003cem\u003eP\u003c/em\u003e = 0.896). No statistically significant differences were observed between the two groups in the difference vector, index of success, and angle of error.\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eIn this retrospective comparative study, we evaluated the clinical outcomes of ICL implantation and PRK as retreatment options for myopic regression following LVC. Our findings indicate that while both procedures are safe and effective, ICL implantation provides distinct advantages in terms of early visual rehabilitation and longitudinal refractive stability. Specifically, the ICL group demonstrated significantly faster visual recovery within the first month and maintained a consistent refractive status without significant fluctuations throughout the 6-month follow-up, whereas the PRK group exhibited significant regression.\u003c/p\u003e \u003cp\u003eSeveral previous studies have reported favorable outcomes of ICL implantation in eyes with myopic regression following LVC. For example, Chung et al. [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] demonstrated excellent short-term efficacy and predictability, with 93% of eyes attaining a postoperative SE within \u0026plusmn;\u0026thinsp;0.50 D and 100% within \u0026plusmn;\u0026thinsp;1.00 D at 3 months postoperatively, and an efficacy index of 1.11. Similarly, Zhang et al. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] reported a 6-month efficacy index of 1.19, safety index of 1.26, and 100% predictability within \u0026plusmn;\u0026thinsp;0.50 D, with all eyes achieving UDVA of 20/20 or better. In the present study, 57% of eyes achieved a postoperative SE within \u0026plusmn;\u0026thinsp;0.50 D, and 100% were within \u0026plusmn;\u0026thinsp;1.00 D, with an efficacy index of 0.98. This relatively lower efficacy and predictability may be attributed to the intentional 0.50 D undercorrection in patients over 40 years of age, who comprised 30% of our cohort. Chen et al. [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] also reported favorable outcomes in a long-term study of ICL implantation after LVC, with a mean follow-up of 39 months, although a mild trend toward myopic regression was observed, possibly due to axial elongation [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. In contrast, our 6-month follow-up demonstrated stable postoperative SE, suggesting good short-term refractive stability.\u003c/p\u003e \u003cp\u003ePRK retreatment has also been investigated for the management of myopic regression. Turad et al. [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] reported that 80% of eyes achieved UDVA of 20/20 or better and 100% achieved UDVA of 20/25 or better, with a mean postoperative SE of \u0026minus;\u0026thinsp;0.38\u0026thinsp;\u0026plusmn;\u0026thinsp;0.57 D and 100% of eyes within \u0026plusmn;\u0026thinsp;1.00 D. Similarly, Moshirfar et al. [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] reported favorable outcomes of PRK retreatment, with 100% of eyes within \u0026plusmn;\u0026thinsp;1.00 D and 87% achieving UDVA of 20/20 or better, yielding a safety index and efficacy index of 0.99 and 1.03, respectively. In our study, the PRK group showed 92% of eyes within \u0026plusmn;\u0026thinsp;1.00 D and 96% achieving UDVA of 20/20 or better, with a safety index of 0.98 and an efficacy index of 0.94. The slightly lower efficacy observed compared to previous studies may be attributed to the intentional undercorrection of 0.50 D performed, as in the ICL group, in 25% of eyes.\u003c/p\u003e \u003cp\u003eNotably, no previous studies have directly compared ICL and PRK for the correction of myopic regression following LVC. Therefore, our study provides meaningful clinical insights by offering the first head-to-head comparative evaluation of these two retreatment modalities in a single-center setting with standardized surgical protocols. As described above, both the ICL and PRK groups demonstrated favorable clinical outcomes at 6 months, comparable to previously reported results. However, ICL was superior to PRK in terms of speed of visual recovery and refractive stability. This is likely attributable to the inherent differences in healing mechanisms, particularly the time-dependent epithelial remodeling required after PRK. Such a difference in early recovery profiles is somewhat expected, but its quantification in a comparative context adds practical value for surgical decision-making. In the analysis of the relationship between attempted and achieved SE at 6 months, the ICL group demonstrated a higher coefficient of determination (\u003cem\u003eR\u003c/em\u003e\u0026sup2; = 0.8855) compared to the PRK group (\u003cem\u003eR\u003c/em\u003e\u0026sup2; = 0.7625), indicating greater predictability in postoperative refractive outcomes with ICL.\u003c/p\u003e \u003cp\u003eVector analysis further revealed differing patterns of astigmatic correction between the groups: the ICL group tended toward undercorrection, whereas the PRK group exhibited mild overcorrection. The undercorrection observed in the ICL group is primarily attributable to the use of non-toric ICL models. In our study, non-toric ICLs were utilized for all eyes despite preoperative astigmatism reaching up to 1.50 D. This clinical decision was based on the expectation that residual astigmatism could be sufficiently managed through incisional techniques\u0026mdash;specifically by placing the main incision on the steep axis and adding opposite corneal incisions for cases exceeding 0.75 D. Furthermore, economic feasibility was a significant consideration; many patients, having already invested in their initial LVC, favored the cost-effectiveness of non-toric ICLs combined with incisional management. Our approach aligns with the findings of Liu et al. [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], who reported that while steep-axis incisions improve correction in eyes with low astigmatism (\u0026le;\u0026thinsp;1.25 D), the mean CI remained 0.84\u0026thinsp;\u0026plusmn;\u0026thinsp;0.30, suggesting residual undercorrection even with optimized incision placement. Similarly, in our cohort, although incisional management was a practical and cost-effective alternative, the astigmatic correction remained suboptimal compared to the results typically achieved with toric lenses. This highlights a trade-off between cost-effectiveness and absolute refractive precision in the context of retreatment.\u003c/p\u003e \u003cp\u003eConversely, the PRK group showed a tendency toward astigmatic overcorrection, with a mean CI of 1.09\u0026thinsp;\u0026plusmn;\u0026thinsp;0.55. A similar trend was reported by Sun et al. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], who investigated transepithelial PRK in virgin eyes and attributed overcorrection to the use of fixed, predefined epithelial profiles. In our cohort, this effect was likely amplified by the irregular epithelial remodeling following the initial LVC. Furthermore, the altered laser ablation rate in the previously treated stroma may have contributed to this overcorrection. Following prior LVC, the corneal stroma undergoes biomechanical and biochemical changes, including variations in hydration and collagen density. Such alterations can lead to an unpredictable stromal response to the excimer laser, potentially resulting in a higher ablation rate during retreatment compared to virgin eyes. Therefore, the synergistic effect of standardized epithelial profiles and altered stromal characteristics likely predisposed the PRK group to the observed overcorrection. This underscores the potential benefit of personalized ablation strategies, such as topography-guided or epithelial mapping-assisted PRK, in post-LVC eyes with non-uniform corneal profiles. Actually, Zhou et al. [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] applied transepithelial, topography-guided, epithelial mapping\u0026ndash;assisted PRK in eyes with residual myopic astigmatism after LVC, reporting improved precision with 100% of eyes within \u0026plusmn;\u0026thinsp;1.00 D of the target.\u003c/p\u003e \u003cp\u003eSeveral limitations must be considered when interpreting the results of this study. First, the retrospective design inherently introduces selection bias, as retreatment modality was not randomized but determined by preoperative parameters and surgeon discretion. Second, the sample size was relatively small, and although the results were statistically robust, larger-scale studies would enhance generalizability. Third, the follow-up duration was limited to 6 months; therefore, long-term complications, regression, or changes in visual acuity cannot be fully assessed. Fourth, all eyes in the ICL group received non-toric ICLs, which limits the generalizability of the astigmatism correction outcomes; use of toric ICLs may have yielded different refractive results. Additionally, subjective parameters such as patient satisfaction, quality of vision, or glare/halo perception were not evaluated but may be clinically meaningful in the context of retreatment.\u003c/p\u003e \u003cp\u003eIn conclusion, both ICL implantation and PRK were found to be effective and safe retreatment options for patients with myopic regression following prior LVC. While 6-month outcomes were comparable between the two modalities, ICL implantation demonstrated superior early visual recovery and faster refractive stability. Although both procedures achieved similar levels of postoperative astigmatism reduction, the patterns of correction differed, with ICL tending toward undercorrection and PRK toward overcorrection. These findings suggest that the choice between ICL and PRK should be carefully tailored to the patient's clinical profile and visual demands. Future prospective studies with larger cohorts, longer follow-up periods, additional patient-reported outcome measures, and objective assessments of visual quality are warranted to further validate these results.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLiterature screening and selection were performed by BKK. BKK and YTC participated in the design of the study. BKK drafted the manuscript and carried out the statistical analysis. YTC interpreted the data. BKK and YTC prepare and review the manuscript. YTC has given final approval of the version to be published. All authors read and approved the final manuscript.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThere were no funding sources for this study.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe datasets analyzed during the current study are available from the corresponding author on reasonable request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe Public Internal Regulatory Board of the Ministry of Health and Welfare, Korea, approved this study (P01-202601-01-036). This research was conducted in accordance with the tenets of the Declaration of Helsinki. Informed consent was waived due to the retrospective design of the study. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eRamin S, Moallemi Rad L, Abbasi A, et al. Myopic regression after photorefractive keratectomy: a retrospective cohort study. Med Hypothesis Discov Innov Ophthalmol. 2019;8:299\u0026ndash;305.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang X, Zhao G, Lin J, Jiang N, Wang Q, Xu Q. Efficacy and safety of topical timolol eye drops in the treatment of myopic regression after laser in situ keratomileusis: a systematic review and meta-analysis. J Ophthalmol. 2015;2015:985071.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlkadi TA, Binyousef FH, Alruwaili SA. Transepithelial photorefractive keratectomy enhancement for myopic regression. Oman J Ophthalmol. 2025;18:138\u0026ndash;43.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChung B, Kim JH, Kang DSY, et al. 3-month surgical outcomes of Implantable Collamer Lens implantation for myopic regression after laser vision correction surgeries: a retrospective case series. BMC Ophthalmol. 2021;21:397.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrahma A, McGhee CN, Craig JP, et al. Safety and predictability of laser in situ keratomileusis enhancement by flap reelevation in high myopia. J Cataract Refract Surg. 2001;27:593\u0026ndash;603.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eP\u0026eacute;rez-Santonja JJ, Ayala MJ, Sakla HF, Ru\u0026iacute;z-Moreno JM, Ali\u0026oacute; JL. Retreatment after laser in situ keratomileusis. Ophthalmology. 1999;106:21\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSharma N, Balasubramanya R, Sinha R, Titiyal JS, Vajpayee RB. Retreatment of LASIK. J Refract Surg. 2006;22:396\u0026ndash;401.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang J, He F, Liu Y, Fan X. Implantable collamer lens with a central hole for residual refractive error correction after corneal refractive surgery. Exp Ther Med. 2020;20:160.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen X, Wang XY, Zhang X, Chen Z, Zhou XT. Implantable collamer lens for residual refractive error after corneal refractive surgery. Int J Ophthalmol. 2016;9:1421\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFotedar R, Mitchell P, Burlutsky G, Wang JJ. Relationship of 10-year change in refraction to nuclear cataract and axial length findings from an older population. Ophthalmology. 2008;115:1273\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSaka N, Ohno-Matsui K, Shimada N, et al. Long-term changes in axial length in adult eyes with pathologic myopia. Am J Ophthalmol. 2010;150:562\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMoshirfar M, Basharat NF, Kelkar N, Bundogji N, Ronquillo YC, Hoopes PC. Visual outcomes of photorefractive keratectomy enhancement after primary LASIK. J Refract Surg. 2022;38:733\u0026ndash;40.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu S, Liu J, Lin F, et al. Efficacy comparison between steep-meridian incision and non-steep-meridian incision in implantable collamer lens surgery with low-to-moderate astigmatism. Ophthalmol Ther. 2023;12:1711\u0026ndash;22.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSun L, Jhanji V, Li S, et al. Vector analysis of astigmatic correction after single-step transepithelial photorefractive keratectomy and femtosecond-assisted laser in-situ keratomileusis for low to moderate myopic astigmatism. Indian J Ophthalmol. 2022;70:3483\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhou W, Reinstein DZ, Chen X, et al. Transepithelial topography-guided ablation assisted by epithelial thickness mapping for treatment of regression after myopic refractive surgery. J Refract Surg. 2019;35:525\u0026ndash;33.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTable 1 to 3 are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"bmc-ophthalmology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"boph","sideBox":"Learn more about [BMC Ophthalmology](http://bmcophthalmol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/boph","title":"BMC Ophthalmology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"ICL, myopic regression, PRK, retreatment","lastPublishedDoi":"10.21203/rs.3.rs-9026883/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9026883/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e: Myopic regression is a common complication after laser vision correction (LVC). While photorefractive keratectomy (PRK) and implantable collamer lens (ICL) implantation are considered effective retreatment options with favorable outcomes, no direct comparative study has evaluated these two modalities for treating regression. Therefore, we aimed to compare the clinical outcomes and astigmatic correction patterns of ICL implantation and PRK in patients with myopic regression after LVC.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e: This retrospective study compared 30 eyes treated with ICL implantation and 24 eyes with transepithelial PRK as retreatment for myopic regression after prior LVC. Clinical outcomes, including visual acuity, refractive stability, and vector analysis of astigmatic correction, were evaluated over a 6-month follow-up period.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e: At 6 months, 100% of eyes in the ICL group and 92% in the PRK group achieved a postoperative spherical equivalent (SE) within ±1.00 D, with uncorrected distance visual acuity (UDVA) of 20/20 or better observed in 100% and 96% of eyes, respectively. The ICL group showed faster early visual recovery with significantly better UDVA at 1 week and 1 month (\u003cem\u003eP\u003c/em\u003e \u0026lt; 0.001 and \u003cem\u003eP\u003c/em\u003e= 0.005), although long-term outcomes at 6 months were comparable between the groups. The ICL group exhibited superior refractive stability, with no significant change in SE over 6 months (\u003cem\u003eP\u003c/em\u003e = 0.095), whereas the PRK group showed a significant change (\u003cem\u003eP\u003c/em\u003e = 0.040). Vector analysis revealed a tendency toward undercorrection in the ICL group (mean correction index: 0.80 ± 0.45) and overcorrection in the PRK group (1.09 ± 0.55), with the PRK group showing significantly greater surgically induced astigmatism (\u003cem\u003eP\u003c/em\u003e = 0.045). No vision-threatening complications occurred in either group.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e: Both ICL implantation and PRK are safe and effective retreatment options for myopic regression after LVC. ICL demonstrated faster early visual recovery and greater refractive stability, while PRK showed higher astigmatic correction with a trend toward overcorrection.\u003c/p\u003e","manuscriptTitle":"Comparison of Clinical Outcomes Between Implantable Collamer Lens Implantation and Photorefractive Keratectomy for Myopic Regression After Laser Vision Correction","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-08 05:29:05","doi":"10.21203/rs.3.rs-9026883/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-04-14T13:58:07+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"263098821356809456720432925732833159298","date":"2026-04-09T09:28:41+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-02T04:50:04+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-03-05T07:31:02+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-05T05:04:46+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-05T05:04:24+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Ophthalmology","date":"2026-03-04T07:00:29+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-ophthalmology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"boph","sideBox":"Learn more about [BMC Ophthalmology](http://bmcophthalmol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/boph","title":"BMC Ophthalmology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"77fad875-2a0d-489c-9d09-1bc9805929d8","owner":[],"postedDate":"April 8th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-08T05:29:05+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-08 05:29:05","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9026883","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9026883","identity":"rs-9026883","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}