Phototherapeutic Keratectomy Results for the Treatment of Corneal Scarring After Pterygium Excision

Phototherapeutic Keratectomy Results for the Treatment of Corneal Scarring After Pterygium Excision | 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 Phototherapeutic Keratectomy Results for the Treatment of Corneal Scarring After Pterygium Excision Berrin Uzunovalı, Demet Mutlu, Mustafa Atas This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3966701/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 Purpose To evaluate the post-treatment corneal changes by corneal topography in patients who underwent phototherapeutic keratectomy (PTK) to reduce anterior corneal irregularity and corneal scarring after pterygium excision. Materials and Methods : Before and after PTK, K1 (flattest central keratometry), K2 (steepest central keratometry), Kmax (maximum keratometry), corneal astigmatism, ISV (index of surface variance), IVA (index of vertical asymmetry), IHA (index of height asymmetry) and IHD (index of height decantration) values were compared. Results Of the 23 patients included in the study, 16 were male (69.6%) and 7 were female (30.4%), with a mean age of 57.09 ± 11.96 years (23–81 years). After PTK surgery patients were asked to come for check-ups at 1., 3., 6. months and at 1 year.The mean time to PTK after pterygium excision was 5.93 ± 1.39 months (4–9 months) and the PTK values taken at the end of the first year were included in the study. The corrected distance visual acuity (CDVA) significantly improved from 0.55 ± 0.28 logMAR (0.10-1.00 logMAR) to 0.46 ± 0.32 logMAR (0.1-1.00 logMAR) after PTK. While the postoperative K1, K2, Kmax and corneal astigmatism values were lower than preoperative values, there was no statistically significant difference compared to preoperative values (respectively p = 0.301, p = 0.060, p = 0.075, p = 0.570). Although ISV, IHA and IHD values were higher than before surgery, the differences were not statistically significant (p > 0.05). In 17 patients, the postoperative IVA value was higher than before the operation, and the difference was statistically significant (p = 0.014). Conclusions PTK can reduce the corneal surface irregularity and the astigmatism in a way that can be corrected with glasses and CDVA will be better. Patients who underwent PTK had a more transparent and more regular cornea. Pterygium excision corneal scar phototherapeutic ablation vertical asymmetry index corneal irregularity Figures Figure 1 Introduction Pterygium is a common chronic ocular surface disease with an overall incidence rate ranging from 1.9 to 9.84% ( 1 , 2 ). Findings reveal that pterygia are probably related to ultraviolet radiation and other environmental factors such as heat, dust, wind, and dry atmosphere ( 3 ). The only method to eliminate pterygium is surgical removal. However, recurrence is still the most common complication despite a spectrum of adjunct therapies, including conjunctival autograft transplantation with mitomycin C (MMC), cyclosporine, β-irradiation, and hyperbaric oxygen ( 4 – 7 ). In addition, the toxicity of these adjuvant drugs to conjunctival cells is quite high. In 1998, Talu H, et al. reported the application of excimer laser phototherapeutic keratectomy (PTK) combined with simple excision to treat recurrent pterygium ( 7 ). Adjuvant use of excimer laser along with simple excision of fibrovascular tissue, helps to ablate the visible residual tissue, thereby smoothening the corneal surface, improving postoperative refractive outcome and reducing postoperative recurrences ( 7 ). Phototherapeutic keratectomy procedures with excimer lasers are useful in the treatment of a variety of corneal diseases, including corneal dystrophies and degenerations, recurrent epithelial erosions, corneal scars, and various other corneal irregularities ( 8 ). Superficial anterior stromal avascular scars (less than 100 microns), are suitable to treat by PTK ( 9 ). These scars may be post-traumatic, postinfectious or post-pterygium excision ( 10 – 12 ). Recent studies have shown that a successful pterygium excision will still result in variable amounts of anterior corneal scarring ( 13 ). PTK ablates the corneal stroma, thereby improving corneal clarity and smoothening the surface ( 14 ). Corneal topography is a useful and powerful tool for evaluating the refractive changes caused by pterygium ( 15 ). In addition, keratometric data and topographic indices obtained by topography are very important in the follow-up of corneal irregularity. In this retrospective study, we aimed to evaluate the changes in the cornea after PTK in patients who underwent PTK due to corneal irregularity and scar tissue after pterygium excision through corneal topography. Materials and Methods Between April 2021 and April 2023, one eye of 23 patients who underwent PTK due to irregularity and scarring of the anterior cornea after pterygium excision at Kayseri City Hospital Ophthalmology Clinic was included in the study. Patients whose pterygium was located in the corneal nasal, exceeded the cornea by 4 mm or more on slit lamp examination, underwent pterygium surgery for the first time, and developed corneal irregularities and scars in corneal topography performed during regular check-ups were included in the study. Patients with keratoconus, dry eye, eyelid dysfunction and any congenital eye disease, patients with herpetic keratitis, and patients with systemic diseases that affect corneal healing such as diabetes, glaucoma and collagen vascular disease were not included in the study. All patients included in the study underwent PTK 5.93 ± 1.39 months after pterygium excision. Corneal topography was taken at 1., 3. and 6. months and 1. year. The data at the first year of the PTK was compared before PTK values. The study was carried out in accordance with the principles accepted in the Declaration of Helsinki, and approval was obtained from the Kayseri Education and Research Hospital Ethics Committee for the study (19.09.2023 / 917). Corneal topography (Pentecam HR, Oculus, Germany) elevation data were measured in a standardized manner based on the reference best-fit sphere (BFS) calculated in a fixed optical region of 8.0 mm. The image of Belin/Ambrósio improved ektasia was evaluated. With corneal topography, keratometric values such as flat keratometry (K1), steep keratometry (K2), maximum keratometry (Kmax), SE (spherical equivalent) and topometric indices such as surface variance index (ISV), vertical asymmetry index (IVA), elevation decentrization index (IHD), elevation asymmetry index (IHA) were evaluated. K1, K2, Kmax, corneal astigmatism, ISV, IVA, IHA and IHD values of all patients before and after PTK were compared. Phototherapeutic Keratectomy Technique For the reliability of the study, PTK was performed by a single surgeon (M.A). Typically, PTK was performed under topical anesthesia using proparacaine hydrochloride 0.5% (Alcaine® 0.5%) sterile eye drops. The corneal epithelium was removed with a hockey spatula after applying alchol for 20 seconds. By focusing the laser device ( VISX STAR S4 excimer laser, Abbott, Abbott Park, IL, USA) on the scar area, the laser ablation diameter was adjusted according to the scar size calculated preoperatively under the microscope, and 50µ ablation was performed in PTK mode. The eye tracking system of the device was turned off and the laser operation was performed in manual mode. After photoablation was completed, 0.002% MMC saturated sponch was kept on the corneal surface for approximately 30 seconds to prevent haze formation. Afterwards, the eye was washed abundantly with a balanced salt solution (BSS). Postoperatively, the bandage contact lens was kept on the surface of the eye until the epithelialization was completed. Postoperatively, fluoromethelone acetate 0.1%, moxifloxacin 0.5% and artificial tear eye drops were given 3 times a day for 1 month. After 1 month,, fluoromethelone acetate 0.1% eye drop was decreased and contnued for 3 months and artificial tears were continued for 6 months. None of the patients had complications after PTK and pterygium excision. Patients were called for controls at 1., 3., 6. months and at 1. year. Measured in the first year follow-up K1, K2, Kmax, corneal astigmatism, ISV, IVA (mean difference between superior and inferior corneal curvature), IHD (provides the degree of decentration in the vertical direction, calculated on a ring with radius 3 mm ), IHA (mean corneal elevation difference between superior and inferior meridian in horizontal meridian ) were evaluated. K1, K2, Kmax, corneal astigmatism, ISV, IVA, IHA and IHD values of all patients before and after PTK were compared. Statistical Analysis Statistical analysis was performed using SPSS 22.0 (SPSS Inc., Chicago, IL, USA) program. Descriptive statistics for numerical variables were expressed as mean ± standard deviation, number and percentage for categorical variables. In the statistical evaluation of the data, normally distributed parameters were evaluated with paired sample-t test and abnormal parameters were evaluated with Wilcoxon signed rank test. The relationship between normally distributed parameters was determined by Pearson test. The results were accepted at the 95% confidence interval, with significance at p < 0.05. Results There were 23 eyes of 23 patients included in the study’s analysis. There were 16 males (69.6%) and 7 were females (30.4%) with a mean age of 57.09 ± 11.96 years (23–81 years). The mean time to PTK after pterygium excision was 5.93 ± 1.39 months (4–9 months), and the time to evaluation after PTK was 1 year. (Table 1 ). The mean K1, K2, and Kmax values before PTK were 42.41 ± 3.44 D, 46.56 ± 3.50 D, and 44.32 ± 3.29 D, respectively, and 41.27 ± 3.04 D, 45.06 ± 3.71 D, and 43.06 ± 3.17 D after PTK, respectively. Although there was a significant decrease in K1, K2 and Kmax values between preoperative and postoperative measurements, the difference between K1, K2 and Kmax values was not statistically significant (respectively p = 0.301, p = 0.060, p = 0.075). Corneal astigmatism value decreased in 14 individuals, increased in 8 individuals and remained unchanged in 1 patient after PTK. Mean corneal astigmatism values were 3.86 ± 2.19 before PTK and 3.80 ± 2.44 after PTK, and there was no statistically significant difference (p = 0.570). While the CDVA before PTK did not change in one patient, it increased in 18 patients and decreased in 4 patients. Cataracts were observed to develop in these patients whose vision decreased. The corrected distance visual acuity (CDVA) significantly improved from 0.55 ± 0.28 logMAR (0.10-1.00 logMAR) to 0.46 ± 0.32 logMAR (0.1-1.00 logMAR) after PTK. The difference is statistically significant (p = 0.021). ISV value decreased in 13 patients and increased in 10 patients after PTK, and mean ISV was 69.13 ± 42.03 before PTK and 73.43 ± 45.13 after PTK. IHA value decreased in 11 patients and increased in 12 patients after PTK, and was 17.26 ± 12.86 before PTK and 22.11 ± 17.21 after PTK. IHD value decreased in 10 patients and increased in 13 patients, from 0.06 ± 0.04 before PTK to 0.08 ± 0.05 after PTK. There was no statistically significant difference between ISV, IHA and IHD values (respectively p = 0.988, p = 0.543, p = 0.181). IVA values decreased in 5 patients, increased in 17 patients and remained the same in 1 patient after PTK, and the difference was statistically significant (p = 0.014) (Table 2 ). A 32 years old male patient’s imaging characteristics before PTK (A) and after 1 year PTK (B) are shown in Fig. 1 . There were possitive correlations between preoperative ISV-IVA (r = 0.928, p < 0.01), ISV-IHA (r = 0.511, p < 0.05), ISV-IHD (p = 0.699, p < 0.01), ISV-IHA (r = 0.543, p < 0.01), IVA-IHD (r = 0.810, p < 0.01) and IHA-IHD (r = 0.707, p < 0.01). During the follow-up period of the study, there was no delayed epithelial healing, IOP elevation, and no patients underwent keratoplasty or additional excimer laser therapy. Table 1 Demographic characteristics of patients Characteristics n:23 Age (year), Mean ± SD Gender, n (%) 57.09 ± 11.96 Female: 7 (30.4), Male: 16 (69.6) Time between pterygium excision and PTK (month), Mean ± SD 5.93 ± 1.39 Follow-up time after PTK (year) 1 year Parameters Before PTK After PTK P Table 2 Comparison of Corneal Topography Values Before and After PTK. Corneal Astigmatism, ISV : Index of surface variance, IVA : Index of vertical asymmetry, IHA : Index of height asymmetry, IHD : Index of height decantration, CDVA :Corrected Distance Visual Acuity. K1(D) 42.41 ± 3.44 41.27 ± 3.04 p = 0.301 K2(D) 46.56 ± 3.50 45.06 ± 3.71 p = 0.060 Kmax (D) 44.32 ± 3.29 43.06 ± 3.17 p = 0.075 Corneal Astigmatism (D) 3.86 ± 2.19 3.80 ± 2.44 p = 0.570 ISV 69.13 ± 42.03 73.43 ± 45.13 p = 0.988 IVA (mm) 0.63 ± 0.43 0.85 ± 0.60 p = 0.014 IHA (µm) 17.26 ± 12.86 22.11 ± 17.21 p = 0.543 IHD (µm) 0.06 ± 0.04 0.08 ± 0.05 p = 0.181 CDVA (logMAR) 0.55 ± 0.28 0.46 ± 0.32 P = 0.021 Discussion Pterygium is a common chronic ocular surface disease and its treatment is surgery. After initial excision, a rough surface with a stromal pit and remnants of the fibrous tissue are generally inevitable and can cause severe irregular astigmatism ( 16 ). Corneal topography is a useful and powerful tool for assessing pterygium-induced refractive changes ( 15 ). Corneal asymmetry indices and corneal cylinder are significantly increased in pterygium patients ( 16 ). Tomidokoro et al. , evaluated the percentage of spread of pterygium over the cornea and found that larger pterygiums adversely affect astigmatism, asymmetry and irregularity of the cornea ( 17 ). Lin and Stern found a significant correlation between the pterygium size and corneal astigmatism; they reported pterygium to induce significant degrees of astigmatism once it exceeded. Also they reported improvement in topographic indices in 16 eyes; corneal astigmatism to reduce from 5.93 ± 2.46D to 1.92 ± 1.68D ( 18 ). Yagmur et al ., studied the effect of pterygium excision in 30 eyes and found topographic astigmatism to reduce from 4.65 ± 3.02 to 2.33 ± 2.26D. In the current study all the topographic parameters were seen to improve significantly following pterygium excision ( 15 ). In the study of K Errais et al . corneal shape, corneal spherical power, simulated keratometric astigmatism, surface regularity index (SRI), and surface asymmetry index (SAI) and manifest refraction spherical equivalent (MRSE) were assessed before and after surgery. In all paremeters there were significant differences after ptergium exision (p < 0.05) ( 19 ). Even after successful pterygium excision, scar tissue and corneal irregularity may remain in the anterior cornea. Although there is no consensus on what is the best treatment for anterior corneal scarring, the ideal ablation protocol should both clear the corneal opacity and improve the irregularity of the cornea. The U.S. Food and Drug Administration approved PTK in 1995 for use in removal of corneal scars or to treat recurrent corneal erosion ( 20 ). PTK can be applied to a wide range of corneal pathologies, including anterior scar removal after injury, infection or surgery, smoothing the corneal surface in eyes with stromal dystrophies or after trauma or surgical complications, or to remove redundant epithelial basement membrane in eyes with recurrent corneal erosions. Thus, this procedure can effectively treat many disorders that would otherwise require manual keratectomy or lamellar or full-thickness corneal transplantation ( 21 ). PTK optimally addresses opacity in approximately the anterior 100 to 150 µm of the cornea. This limitation is related to potential for inducing iatrogenic ectasia and induced hyperopic shift that can interfere with visual function despite removal of opacity. Importantly, significant improvement in visual performance can be obtained in many eyes without removing all of the corneal stromal opacity in a particular cornea. Also, in many cases of stromal opacity there is also associated surface irregularity ( 22 ). PTK is preferred because it is less invasive and more effective ( 23 ). In many studies conducted in the literature to improve corneal irregularity after corneal scarring, a significant improvement was observed in topographic parameters when preoperative and postoperative data were compared ( 24 , 25 ). In a study conducted by SW Rush et al ., PTK was performed on 22 patients with anterior corneal scars. While corneal cylinder showed significant improvement (P = 0.0173) after PTK, it was determined that there was no improvement in SAI (P = 0.0849) and the SRI (P = 0.0543) ( 25 ). In another study conducted by Rush SW et al ., corneal cylinder, SAI and SRI were significantly improved in 64 eyes that underwent PTK due to corneal scarring (p = 0.0045, p = 0.0054, p = 0.0047, respectively) ( 26 ). In the other study of Rush SW et al , all 11 eyes tolerated both the pterygium excision and T-PTK procedure, the topographic SAI, topographic SRI, and topographic projected visual acuity significantly improved after T-PTK ( p = 0.0092, p = 0.0022, and p = 0.0002, respectively) ( 27 ). In our series, in accordance with the Rush et al. , K1, K2 and Kmax values have improved significantly. K1 value was 42.41 D preoperatively and 41.47 D postoperatively. There was a decrease in K2 value from 46.56 D to 45.06 D and in Kmax value from 44.32 D to 43.06 D (p = 0.301, p = 0.06 respectively). While there was a significant improvement in ISV, IHA and IHD values, the difference was not statistically significant. IVA is the difference between superior and inferior corneal curvature, and hence the value of curvature symmetry ( 28 , 29 ). In our study, we found a statistically significant difference between preoperative and postoperative values in IVA value (p = 0.014). There will be a statistically significant difference in corneal surface irregularity values with PTK repetition. In a study conducted by T. Walkow et al ., PTK was performed on 30 eyes that underwent pterygium excision, and astigmatism was significantly lower than the control group ( 30 ). In our study, although the corneal astigmatism value decreased compared to the preoperative period, there was no statistically significant difference (p = 0.570). In our study there was an improvement in postoperative CDVA compared to preoperative CDVA from 0.55 ± 0.28 logMAR to 0.46 ± 0.32 logMAR in accordance with the literatüre ( 31 , 32 , 33 ). PTK, can improve the visual acuity as well decrease the amount of irregular astigmatism and irregular corneal surface. This suggests that the gross amount of astigmatism may not change, but the astigmatism which is correctable with glasses can be markedly improved following PTK. The limitations of our study are that it was retrospective, there was no control group, the number of patients was low. More reliable results can be obtained with studies in which more cases are followed. The fact that the corneal scar depth was not determined by OCT is the missing aspect of our study. In the literature, there are limited number of studies on the effects of PTK on topographic values for corneal scarring reduction after pterygium excision. Despite all its limitations, we found that the cornea was topographically flattened and the anterior stromal scar decreased after PTK similar to the other studies. In addition to other studies, we also found a significant improvement in IVA value topographically. Since a more regular corneal surface will positively affect the visual prognosis of the patient, we think that PTK should be repeated until the desired result is obtained. As a result, PTK may not eliminate most of the astigmatism, but it does reduce the astigmatism in a way that can be corrected with glasses. Patients who underwent PTK had a more transparent and more regular cornea than before surgery. PTK is a safe, simple and effective procedure which delays the need for penetrating keratoplasty, and its associated complications and side effects. Declarations Ethical approval The tenets of the Declaration of Helsinki were followed and the study was carried out as approved by the competent ethics committee (Kayseri City Education and Research Hospital No.917). Disclosure statement No potential conflict of interest was reported by the author(s). Data availability statement The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Funding This study was not funded by any agency. References Song P, Chang X, Wang M, An L. 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Arfaj K, Jain M,Hantera M. Phototherapeutic keratectomy outcomes in superficial corneal opacities. Ophthalmol Eye Dis. 2011 Mar 16:3:1-6.doi: 10.4137/OED.S5985. Print 2011. Rush SW, Han DY, Rush RB. Optical coherence tomography-guided transepithelial phototherapeutic keratectomy for the treatment of anterior corneal scarring. Am J Ophthalmol. 2013; 156(6):1088-94. doi: 10.1016/j.ajo.2013.06.026. Epub 2013 Sep 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. 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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-3966701","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":273646366,"identity":"03eb72be-9194-4f3e-af41-a710a4b53b22","order_by":0,"name":"Berrin Uzunovalı","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA20lEQVRIiWNgGAWjYHACA2YQycbAfAzMZWMnXgtbGgNDApDBTKwWBgYeM7AWBkJa+KWbt30uqLiXzyfd8+3Bxx/b5PmYGRg/fMzBrUVyzrHi2TPOFFu2yZzdbjgj4bZhGzMDs+TMbXhcdSPHmJm3LcGATSJ3mzRPwm1GoBY2Zl6CWv6BtOQ8A2mxJ1JLA1gLG0hLIkEtIL8wzzgG0pJmJjkj7XZyGzNjM16/AENsM3NBTYKB/IzkZxIfbG7bzm9vPvjhIx4tDBKYQowNeNRj1zIKRsEoGAWjABUAABszRUF4sBlCAAAAAElFTkSuQmCC","orcid":"","institution":"Kayseri City Education and Research Hospital Ophthalmology","correspondingAuthor":true,"prefix":"","firstName":"Berrin","middleName":"","lastName":"Uzunovalı","suffix":""},{"id":273646367,"identity":"07bd581a-4ea4-4a07-88fe-43eb0a3b4076","order_by":1,"name":"Demet Mutlu","email":"","orcid":"","institution":"Kayseri City Education and Research Hospital Ophthalmology","correspondingAuthor":false,"prefix":"","firstName":"Demet","middleName":"","lastName":"Mutlu","suffix":""},{"id":273646368,"identity":"eb142968-c6e4-488d-9899-31ddea8b1407","order_by":2,"name":"Mustafa Atas","email":"","orcid":"","institution":"TC İstanbul Üsküdar Üniversitesi","correspondingAuthor":false,"prefix":"","firstName":"Mustafa","middleName":"","lastName":"Atas","suffix":""}],"badges":[],"createdAt":"2024-02-18 10:44:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3966701/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3966701/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":51445872,"identity":"6feaed71-9de0-42a4-afca-bac61276ccc4","added_by":"auto","created_at":"2024-02-21 18:12:43","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":236728,"visible":true,"origin":"","legend":"\u003cp\u003eA 32 years old male patient’s imaging characteristics before PTK (A) and after 1 year PTK (B).\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3966701/v1/f937a2d7f1b04c69fd07d30a.jpg"},{"id":51955478,"identity":"a6bae5fa-0bf7-4405-af36-6767746f7eb8","added_by":"auto","created_at":"2024-03-04 14:12:48","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":434737,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3966701/v1/f9d76546-57ee-4c6f-8e8c-3d9ce4131d73.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Phototherapeutic Keratectomy Results for the Treatment of Corneal Scarring After Pterygium Excision","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePterygium is a common chronic ocular surface disease with an overall incidence rate ranging from 1.9 to 9.84% (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). Findings reveal that pterygia are probably related to ultraviolet radiation and other environmental factors such as heat, dust, wind, and dry atmosphere (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). The only method to eliminate pterygium is surgical removal. However, recurrence is still the most common complication despite a spectrum of adjunct therapies, including conjunctival autograft transplantation with mitomycin C (MMC), cyclosporine, β-irradiation, and hyperbaric oxygen (\u003cspan additionalcitationids=\"CR5 CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e7\u003c/span\u003e). In addition, the toxicity of these adjuvant drugs to conjunctival cells is quite high.\u003c/p\u003e \u003cp\u003eIn 1998, Talu H, et al. reported the application of excimer laser phototherapeutic keratectomy (PTK) combined with simple excision to treat recurrent pterygium (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e7\u003c/span\u003e). Adjuvant use of excimer laser along with simple excision of fibrovascular tissue, helps to ablate the visible residual tissue, thereby smoothening the corneal surface, improving postoperative refractive outcome and reducing postoperative recurrences (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e7\u003c/span\u003e). Phototherapeutic keratectomy procedures with excimer lasers are useful in the treatment of a variety of corneal diseases, including corneal dystrophies and degenerations, recurrent epithelial erosions, corneal scars, and various other corneal irregularities (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e8\u003c/span\u003e). Superficial anterior stromal avascular scars (less than 100 microns), are suitable to treat by PTK (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e9\u003c/span\u003e). These scars may be post-traumatic, postinfectious or post-pterygium excision (\u003cspan additionalcitationids=\"CR11\" citationid=\"CR7\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e12\u003c/span\u003e). Recent studies have shown that a successful pterygium excision will still result in variable amounts of anterior corneal scarring (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e13\u003c/span\u003e). PTK ablates the corneal stroma, thereby improving corneal clarity and smoothening the surface (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e14\u003c/span\u003e).\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eCorneal topography is a useful and powerful tool for evaluating the refractive changes caused by pterygium (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e15\u003c/span\u003e). In addition, keratometric data and topographic indices obtained by topography are very important in the follow-up of corneal irregularity.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eIn this retrospective study, we aimed to evaluate the changes in the cornea after PTK in patients who underwent PTK due to corneal irregularity and scar tissue after pterygium excision through corneal topography.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eBetween April 2021 and April 2023, one eye of 23 patients who underwent PTK due to irregularity and scarring of the anterior cornea after pterygium excision at Kayseri City Hospital Ophthalmology Clinic was included in the study. Patients whose pterygium was located in the corneal nasal, exceeded the cornea by 4 mm or more on slit lamp examination, underwent pterygium surgery for the first time, and developed corneal irregularities and scars in corneal topography performed during regular check-ups were included in the study. Patients with keratoconus, dry eye, eyelid dysfunction and any congenital eye disease, patients with herpetic keratitis, and patients with systemic diseases that affect corneal healing such as diabetes, glaucoma and collagen vascular disease were not included in the study. All patients included in the study underwent PTK 5.93\u0026thinsp;\u0026plusmn;\u0026thinsp;1.39 months after pterygium excision. Corneal topography was taken at 1., 3. and 6. months and 1. year. The data at the first year of the PTK was compared before PTK values. The study was carried out in accordance with the principles accepted in the Declaration of Helsinki, and approval was obtained from the Kayseri Education and Research Hospital Ethics Committee for the study (19.09.2023 / 917).\u003c/p\u003e \u003cp\u003eCorneal topography (Pentecam HR, Oculus, Germany) elevation data were measured in a standardized manner based on the reference best-fit sphere (BFS) calculated in a fixed optical region of 8.0 mm. The image of Belin/Ambr\u0026oacute;sio improved ektasia was evaluated. With corneal topography, keratometric values such as flat keratometry (K1), steep keratometry (K2), maximum keratometry (Kmax), SE (spherical equivalent) and topometric indices such as surface variance index (ISV), vertical asymmetry index (IVA), elevation decentrization index (IHD), elevation asymmetry index (IHA) were evaluated. K1, K2, Kmax, corneal astigmatism, ISV, IVA, IHA and IHD values of all patients before and after PTK were compared.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003ePhototherapeutic Keratectomy Technique\u003c/strong\u003e \u003cp\u003eFor the reliability of the study, PTK was performed by a single surgeon (M.A). Typically, PTK was performed under topical anesthesia using proparacaine hydrochloride 0.5% (Alcaine\u0026reg; 0.5%) sterile eye drops. The corneal epithelium was removed with a hockey spatula after applying alchol for 20 seconds. By focusing the laser device ( VISX STAR S4 excimer laser, Abbott, Abbott Park, IL, USA) on the scar area, the laser ablation diameter was adjusted according to the scar size calculated preoperatively under the microscope, and 50\u0026micro; ablation was performed in PTK mode. The eye tracking system of the device was turned off and the laser operation was performed in manual mode. After photoablation was completed, 0.002% MMC saturated sponch was kept on the corneal surface for approximately 30 seconds to prevent haze formation. Afterwards, the eye was washed abundantly with a balanced salt solution (BSS). Postoperatively, the bandage contact lens was kept on the surface of the eye until the epithelialization was completed. Postoperatively, fluoromethelone acetate 0.1%, moxifloxacin 0.5% and artificial tear eye drops were given 3 times a day for 1 month. After 1 month,, fluoromethelone acetate 0.1% eye drop was decreased and contnued for 3 months and artificial tears were continued for 6 months. None of the patients had complications after PTK and pterygium excision. Patients were called for controls at 1., 3., 6. months and at 1. year. Measured in the first year follow-up K1, K2, Kmax, corneal astigmatism, ISV, IVA (mean difference between superior and inferior corneal curvature), IHD (provides the degree of decentration in the vertical direction, calculated on a ring with radius 3 mm ), IHA (mean corneal elevation difference between superior and inferior meridian in horizontal meridian ) were evaluated. K1, K2, Kmax, corneal astigmatism, ISV, IVA, IHA and IHD values of all patients before and after PTK were compared.\u003c/p\u003e \u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eStatistical analysis was performed using SPSS 22.0 (SPSS Inc., Chicago, IL, USA) program. Descriptive statistics for numerical variables were expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation, number and percentage for categorical variables. In the statistical evaluation of the data, normally distributed parameters were evaluated with paired sample-t test and abnormal parameters were evaluated with Wilcoxon signed rank test. The relationship between normally distributed parameters was determined by Pearson test. The results were accepted at the 95% confidence interval, with significance at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eThere were 23 eyes of 23 patients included in the study\u0026rsquo;s analysis. There were 16 males (69.6%) and 7 were females (30.4%) with a mean age of 57.09\u0026thinsp;\u0026plusmn;\u0026thinsp;11.96 years (23\u0026ndash;81 years). The mean time to PTK after pterygium excision was 5.93\u0026thinsp;\u0026plusmn;\u0026thinsp;1.39 months (4\u0026ndash;9 months), and the time to evaluation after PTK was 1 year. (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The mean K1, K2, and Kmax values before PTK were 42.41\u0026thinsp;\u0026plusmn;\u0026thinsp;3.44 D, 46.56\u0026thinsp;\u0026plusmn;\u0026thinsp;3.50 D, and 44.32\u0026thinsp;\u0026plusmn;\u0026thinsp;3.29 D, respectively, and 41.27\u0026thinsp;\u0026plusmn;\u0026thinsp;3.04 D, 45.06\u0026thinsp;\u0026plusmn;\u0026thinsp;3.71 D, and 43.06\u0026thinsp;\u0026plusmn;\u0026thinsp;3.17 D after PTK, respectively. Although there was a significant decrease in K1, K2 and Kmax values between preoperative and postoperative measurements, the difference between K1, K2 and Kmax values was not statistically significant (respectively p\u0026thinsp;=\u0026thinsp;0.301, p\u0026thinsp;=\u0026thinsp;0.060, p\u0026thinsp;=\u0026thinsp;0.075). Corneal astigmatism value decreased in 14 individuals, increased in 8 individuals and remained unchanged in 1 patient after PTK. Mean corneal astigmatism values were 3.86\u0026thinsp;\u0026plusmn;\u0026thinsp;2.19 before PTK and 3.80\u0026thinsp;\u0026plusmn;\u0026thinsp;2.44 after PTK, and there was no statistically significant difference (p\u0026thinsp;=\u0026thinsp;0.570). While the CDVA before PTK did not change in one patient, it increased in 18 patients and decreased in 4 patients. Cataracts were observed to develop in these patients whose vision decreased. The corrected distance visual acuity (CDVA) significantly improved from 0.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.28 logMAR (0.10-1.00 logMAR) to 0.46\u0026thinsp;\u0026plusmn;\u0026thinsp;0.32 logMAR (0.1-1.00 logMAR) after PTK. The difference is statistically significant (p\u0026thinsp;=\u0026thinsp;0.021). ISV value decreased in 13 patients and increased in 10 patients after PTK, and mean ISV was 69.13\u0026thinsp;\u0026plusmn;\u0026thinsp;42.03 before PTK and 73.43\u0026thinsp;\u0026plusmn;\u0026thinsp;45.13 after PTK. IHA value decreased in 11 patients and increased in 12 patients after PTK, and was 17.26\u0026thinsp;\u0026plusmn;\u0026thinsp;12.86 before PTK and 22.11\u0026thinsp;\u0026plusmn;\u0026thinsp;17.21 after PTK. IHD value decreased in 10 patients and increased in 13 patients, from 0.06\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04 before PTK to 0.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05 after PTK. There was no statistically significant difference between ISV, IHA and IHD values (respectively p\u0026thinsp;=\u0026thinsp;0.988, p\u0026thinsp;=\u0026thinsp;0.543, p\u0026thinsp;=\u0026thinsp;0.181). IVA values decreased in 5 patients, increased in 17 patients and remained the same in 1 patient after PTK, and the difference was statistically significant (p\u0026thinsp;=\u0026thinsp;0.014) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). A 32 years old male patient\u0026rsquo;s imaging characteristics before PTK (A) and after 1 year PTK (B) are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. There were possitive correlations between preoperative ISV-IVA (r\u0026thinsp;=\u0026thinsp;0.928, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01), ISV-IHA (r\u0026thinsp;=\u0026thinsp;0.511, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), ISV-IHD (p\u0026thinsp;=\u0026thinsp;0.699, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01), ISV-IHA (r\u0026thinsp;=\u0026thinsp;0.543, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01), IVA-IHD (r\u0026thinsp;=\u0026thinsp;0.810, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01) and IHA-IHD (r\u0026thinsp;=\u0026thinsp;0.707, p\u0026thinsp;\u0026lt;\u0026thinsp;0.01). During the follow-up period of the study, there was no delayed epithelial healing, IOP elevation, and no patients underwent keratoplasty or additional excimer laser therapy.\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\u003eDemographic characteristics of patients\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eCharacteristics n:23\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAge (year), Mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003eGender, n (%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e57.09\u0026thinsp;\u0026plusmn;\u0026thinsp;11.96\u003c/p\u003e \u003cp\u003eFemale: 7 (30.4), Male: 16 (69.6)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTime between pterygium excision and PTK (month), Mean\u003c/b\u003e\u0026thinsp;\u0026plusmn;\u0026thinsp;\u003cb\u003eSD\u003c/b\u003e 5.93\u0026thinsp;\u0026plusmn;\u0026thinsp;1.39\u003c/p\u003e \u003cp\u003e\u003cb\u003eFollow-up time after PTK (year)\u003c/b\u003e 1 year\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"2\"\u003e\u003cb\u003eParameters Before PTK After PTK P\u003c/b\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of Corneal Topography Values Before and After PTK. Corneal Astigmatism, \u003cem\u003eISV\u003c/em\u003e: Index of surface variance, \u003cem\u003eIVA\u003c/em\u003e: Index of vertical asymmetry, \u003cem\u003eIHA\u003c/em\u003e: Index of height asymmetry, \u003cem\u003eIHD\u003c/em\u003e: Index of height decantration,\u003cem\u003eCDVA\u003c/em\u003e:Corrected Distance Visual Acuity.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eK1(D)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e42.41\u0026thinsp;\u0026plusmn;\u0026thinsp;3.44\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41.27\u0026thinsp;\u0026plusmn;\u0026thinsp;3.04\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.301\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eK2(D)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e46.56\u0026thinsp;\u0026plusmn;\u0026thinsp;3.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e45.06\u0026thinsp;\u0026plusmn;\u0026thinsp;3.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.060\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eKmax (D)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e44.32\u0026thinsp;\u0026plusmn;\u0026thinsp;3.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e43.06\u0026thinsp;\u0026plusmn;\u0026thinsp;3.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.075\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCorneal Astigmatism (D)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.86\u0026thinsp;\u0026plusmn;\u0026thinsp;2.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.80\u0026thinsp;\u0026plusmn;\u0026thinsp;2.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.570\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eISV\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e69.13\u0026thinsp;\u0026plusmn;\u0026thinsp;42.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e73.43\u0026thinsp;\u0026plusmn;\u0026thinsp;45.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.988\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIVA (mm)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.63\u0026thinsp;\u0026plusmn;\u0026thinsp;0.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.85\u0026thinsp;\u0026plusmn;\u0026thinsp;0.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003ep\u0026thinsp;=\u0026thinsp;0.014\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIHA (\u0026micro;m)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e17.26\u0026thinsp;\u0026plusmn;\u0026thinsp;12.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22.11\u0026thinsp;\u0026plusmn;\u0026thinsp;17.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.543\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIHD (\u0026micro;m)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.06\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep\u0026thinsp;=\u0026thinsp;0.181\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCDVA (logMAR)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.46\u0026thinsp;\u0026plusmn;\u0026thinsp;0.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP\u0026thinsp;=\u0026thinsp;0.021\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003ePterygium is a common chronic ocular surface disease and its treatment is surgery. After initial excision, a rough surface with a stromal pit and remnants of the fibrous tissue are generally inevitable and can cause severe irregular astigmatism (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e16\u003c/span\u003e). Corneal topography is a useful and powerful tool for assessing pterygium-induced refractive changes (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e15\u003c/span\u003e). Corneal asymmetry indices and corneal cylinder are significantly increased in pterygium patients (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e16\u003c/span\u003e). Tomidokoro \u003cem\u003eet al.\u003c/em\u003e, evaluated the percentage of spread of pterygium over the cornea and found that larger pterygiums adversely affect astigmatism, asymmetry and irregularity of the cornea (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e17\u003c/span\u003e). Lin and Stern found a significant correlation between the pterygium size and corneal astigmatism; they reported pterygium to induce significant degrees of astigmatism once it exceeded. Also they reported improvement in topographic indices in 16 eyes; corneal astigmatism to reduce from 5.93\u0026thinsp;\u0026plusmn;\u0026thinsp;2.46D to 1.92\u0026thinsp;\u0026plusmn;\u0026thinsp;1.68D (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e18\u003c/span\u003e). Yagmur \u003cem\u003eet al\u003c/em\u003e., studied the effect of pterygium excision in 30 eyes and found topographic astigmatism to reduce from 4.65\u0026thinsp;\u0026plusmn;\u0026thinsp;3.02 to 2.33\u0026thinsp;\u0026plusmn;\u0026thinsp;2.26D. In the current study all the topographic parameters were seen to improve significantly following pterygium excision (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e15\u003c/span\u003e). In the study of K Errais \u003cem\u003eet al\u003c/em\u003e. corneal shape, corneal spherical power, simulated keratometric astigmatism, surface regularity index (SRI), and surface asymmetry index (SAI) and manifest refraction spherical equivalent (MRSE) were assessed before and after surgery. In all paremeters there were significant differences after ptergium exision (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e19\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eEven after successful pterygium excision, scar tissue and corneal irregularity may remain in the anterior cornea. Although there is no consensus on what is the best treatment for anterior corneal scarring, the ideal ablation protocol should both clear the corneal opacity and improve the irregularity of the cornea. The U.S. Food and Drug Administration approved PTK in 1995 for use in removal of corneal scars or to treat recurrent corneal erosion (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e20\u003c/span\u003e). PTK can be applied to a wide range of corneal pathologies, including anterior scar removal after injury, infection or surgery, smoothing the corneal surface in eyes with stromal dystrophies or after trauma or surgical complications, or to remove redundant epithelial basement membrane in eyes with recurrent corneal erosions. Thus, this procedure can effectively treat many disorders that would otherwise require manual keratectomy or lamellar or full-thickness corneal transplantation (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e21\u003c/span\u003e). PTK optimally addresses opacity in approximately the anterior 100 to 150 \u0026micro;m of the cornea. This limitation is related to potential for inducing iatrogenic ectasia and induced hyperopic shift that can interfere with visual function despite removal of opacity. Importantly, significant improvement in visual performance can be obtained in many eyes without removing all of the corneal stromal opacity in a particular cornea. Also, in many cases of stromal opacity there is also associated surface irregularity (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e22\u003c/span\u003e).\u003c/p\u003e \u003cp\u003ePTK is preferred because it is less invasive and more effective (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e23\u003c/span\u003e). In many studies conducted in the literature to improve corneal irregularity after corneal scarring, a significant improvement was observed in topographic parameters when preoperative and postoperative data were compared (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e25\u003c/span\u003e). In a study conducted by SW Rush \u003cem\u003eet al\u003c/em\u003e., PTK was performed on 22 patients with anterior corneal scars. While corneal cylinder showed significant improvement (P\u0026thinsp;=\u0026thinsp;0.0173) after PTK, it was determined that there was no improvement in SAI (P\u0026thinsp;=\u0026thinsp;0.0849) and the SRI (P\u0026thinsp;=\u0026thinsp;0.0543) (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e25\u003c/span\u003e). In another study conducted by Rush SW \u003cem\u003eet al\u003c/em\u003e., corneal cylinder, SAI and SRI were significantly improved in 64 eyes that underwent PTK due to corneal scarring (p\u0026thinsp;=\u0026thinsp;0.0045, p\u0026thinsp;=\u0026thinsp;0.0054, p\u0026thinsp;=\u0026thinsp;0.0047, respectively) (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e26\u003c/span\u003e). In the other study of Rush SW \u003cem\u003eet al\u003c/em\u003e, all 11 eyes tolerated both the pterygium excision and T-PTK procedure, the topographic SAI, topographic SRI, and topographic projected visual acuity significantly improved after T-PTK (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0092, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0022, and \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0002, respectively) (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e27\u003c/span\u003e). In our series, in accordance with the Rush \u003cem\u003eet al.\u003c/em\u003e, K1, K2 and Kmax values have improved significantly. K1 value was 42.41 D preoperatively and 41.47 D postoperatively. There was a decrease in K2 value from 46.56 D to 45.06 D and in Kmax value from 44.32 D to 43.06 D (p\u0026thinsp;=\u0026thinsp;0.301, p\u0026thinsp;=\u0026thinsp;0.06 respectively). While there was a significant improvement in ISV, IHA and IHD values, the difference was not statistically significant. IVA is the difference between superior and inferior corneal curvature, and hence the value of curvature symmetry (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e29\u003c/span\u003e). In our study, we found a statistically significant difference between preoperative and postoperative values in IVA value (p\u0026thinsp;=\u0026thinsp;0.014). There will be a statistically significant difference in corneal surface irregularity values with PTK repetition.\u003c/p\u003e \u003cp\u003eIn a study conducted by T. Walkow \u003cem\u003eet al\u003c/em\u003e., PTK was performed on 30 eyes that underwent pterygium excision, and astigmatism was significantly lower than the control group (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e30\u003c/span\u003e). In our study, although the corneal astigmatism value decreased compared to the preoperative period, there was no statistically significant difference (p\u0026thinsp;=\u0026thinsp;0.570).\u003c/p\u003e \u003cp\u003eIn our study there was an improvement in postoperative CDVA compared to preoperative CDVA from 0.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.28 logMAR to 0.46\u0026thinsp;\u0026plusmn;\u0026thinsp;0.32 logMAR in accordance with the literat\u0026uuml;re (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e33\u003c/span\u003e). PTK, can improve the visual acuity as well decrease the amount of irregular astigmatism and irregular corneal surface. This suggests that the gross amount of astigmatism may not change, but the astigmatism which is correctable with glasses can be markedly improved following PTK.\u003c/p\u003e \u003cp\u003eThe limitations of our study are that it was retrospective, there was no control group, the number of patients was low. More reliable results can be obtained with studies in which more cases are followed. The fact that the corneal scar depth was not determined by OCT is the missing aspect of our study. In the literature, there are limited number of studies on the effects of PTK on topographic values for corneal scarring reduction after pterygium excision. Despite all its limitations, we found that the cornea was topographically flattened and the anterior stromal scar decreased after PTK similar to the other studies. In addition to other studies, we also found a significant improvement in IVA value topographically. Since a more regular corneal surface will positively affect the visual prognosis of the patient, we think that PTK should be repeated until the desired result is obtained.\u003c/p\u003e \u003cp\u003eAs a result, PTK may not eliminate most of the astigmatism, but it does reduce the astigmatism in a way that can be corrected with glasses. Patients who underwent PTK had a more transparent and more regular cornea than before surgery. PTK is a safe, simple and effective procedure which delays the need for penetrating keratoplasty, and its associated complications and side effects.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthical approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe tenets of the Declaration of Helsinki were followed and the study was carried out as approved by the competent ethics committee (Kayseri City Education and Research Hospital\u0026nbsp;No.917).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDisclosure statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo potential conflict of interest was reported by the author(s).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was not funded by any agency.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eSong P, Chang X, Wang M, An L. 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J Refract Surg. 2005 Mar-Apr;21(2):166-70. doi:10.3928/1081-597X-20050301-12.\u003c/li\u003e\n\u003cli\u003eWalland MJ, Stevens JD, Steele AD. The effect of recurrent pterygium on corneal topography. Cornea. 1994 Sep;13(5):463-4. doi: 10.1097/00003226-199409000-00016.\u003c/li\u003e\n\u003cli\u003eTomidokoro A, Miyata K, Sakaguchi Y, Samejima T, Tokunaga T, Oshika T. Effects of pterygium on corneal spherical power and astigmatism. Ophthalmology. 2000 Aug;107(8):1568-71. doi: 10.1016/s0161-6420(00)00219-0.\u003c/li\u003e\n\u003cli\u003eStern GA, Lin A. Effect of pterygium excision on induced corneal topographic abnormalities. Cornea. 1998 Jan;17(1):23-7. doi: 10.1097/00003226-199801000-00004.\u003c/li\u003e\n\u003cli\u003eTomidokoro A, Miyata K, Sakaguchi Y, Samejima T, Tokunaga T, Oshika T. Effects of pterygium on corneal spherical power and astigmatism. Ophthalmology. 2000 Aug;107(8):1568-71. doi: 10.1016/s0161-6420(00)00219-0.\u003c/li\u003e\n\u003cli\u003eErrais K, Bouden J, Mili-Boussen I, Anane R, Beltaif O, Meddeb Ouertani A. Effect of pterygium surgery on corneal topography. Eur J Ophthalmol. 2008 Mar-Apr;18(2):177-81. doi: 10.1177/112067210801800203.\u003c/li\u003e\n\u003cli\u003eAyres BD, Rapuano CJ. Excimer laser phototherapeutic keratectomy. Ocul Surf. 2006 Oct;4(4):196-206. doi: 10.1016/s1542-0124(12)70166-0.\u003c/li\u003e\n\u003cli\u003eThompson VM. Excimer laser phototherapeutic keratectomy: clinical and surgical aspects. Ophthalmic Surg Lasers. 1995 Sep-Oct;26(5):461-72.\u003c/li\u003e\n\u003cli\u003eMeyer JC, Stulting RD, Thompson KP, Durrie DS. Late onset of corneal scar after excimer laser photorefractive keratectomy. Am J Ophthalmol. 1996 May;121(5):529-39. doi:10.1016/s0002-9394(14)75427-3.\u003c/li\u003e\n\u003cli\u003eHafner A, Langenbucher A, Seitz B. 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German. doi: 10.1055/s-2008-1035302.\u003c/li\u003e\n\u003cli\u003eKaiser K.P.,Wissiak E, M\u0026uuml;ller T. Combined transepithelial PTK and topography-guided PRK for treatment of trauma-related corneal scarring.2022Mar;119(3):250-257.doi: 10.1007/s00347-021-01480-8.\u0026nbsp;Epub 2021 Aug 25.\u003c/li\u003e\n\u003cli\u003eArfaj K, Jain M,Hantera M. Phototherapeutic keratectomy outcomes in superficial corneal opacities. Ophthalmol Eye Dis.\u0026nbsp;2011 Mar 16:3:1-6.doi: 10.4137/OED.S5985.\u0026nbsp;Print 2011.\u003c/li\u003e\n\u003cli\u003eRush SW, Han DY, Rush RB. Optical coherence tomography-guided transepithelial phototherapeutic keratectomy for the treatment of anterior corneal scarring. Am J Ophthalmol. 2013; 156(6):1088-94. doi: 10.1016/j.ajo.2013.06.026. Epub 2013 Sep\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":"Pterygium excision, corneal scar, phototherapeutic ablation, vertical asymmetry index, corneal irregularity","lastPublishedDoi":"10.21203/rs.3.rs-3966701/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3966701/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003ePurpose\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo evaluate the post-treatment corneal changes by corneal topography in patients who underwent phototherapeutic keratectomy (PTK) to reduce anterior corneal irregularity and corneal scarring after pterygium excision. Materials and\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e: Before and after PTK, K1 (flattest central keratometry), K2 (steepest central keratometry), Kmax (maximum keratometry), corneal astigmatism, ISV (index of surface variance), IVA (index of vertical asymmetry), IHA (index of height asymmetry) and IHD (index of height decantration) values were compared.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOf the 23 patients included in the study, 16 were male (69.6%) and 7 were female (30.4%), with a mean age of 57.09 ± 11.96 years (23–81 years). After PTK surgery patients were asked to come for check-ups at 1., 3., 6. months and at 1 year.The mean time to PTK after pterygium excision was 5.93 ± 1.39 months (4–9 months) and the PTK values taken at the end of the first year were included in the study. The corrected distance visual acuity (CDVA) significantly improved from 0.55 ± 0.28 logMAR (0.10-1.00 logMAR) to 0.46 ± 0.32 logMAR (0.1-1.00 logMAR) after PTK. While the postoperative K1, K2, Kmax and corneal astigmatism values were lower than preoperative values, there was no statistically significant difference compared to preoperative values (respectively p = 0.301, p = 0.060, p = 0.075, p = 0.570). Although ISV, IHA and IHD values were higher than before surgery, the differences were not statistically significant (p \u0026gt; 0.05). In 17 patients, the postoperative IVA value was higher than before the operation, and the difference was statistically significant (p = 0.014).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePTK can reduce the corneal surface irregularity and the astigmatism in a way that can be corrected with glasses and CDVA will be better. Patients who underwent PTK had a more transparent and more regular cornea.\u003c/p\u003e","manuscriptTitle":"Phototherapeutic Keratectomy Results for the Treatment of Corneal Scarring After Pterygium Excision","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-02-21 18:12:30","doi":"10.21203/rs.3.rs-3966701/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":"c62949f6-7621-4d52-b67d-80fac431e10b","owner":[],"postedDate":"February 21st, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-03-04T14:10:12+00:00","versionOfRecord":[],"versionCreatedAt":"2024-02-21 18:12:30","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3966701","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3966701","identity":"rs-3966701","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}