Photorefractive Keratectomy in Young Asian Aviators with Low-Moderate Myopia (original) (raw)
Related papers
Cornea, 2009
Purpose: To evaluate 8-year results of photorefractive keratectomy (PRK) for myopia in terms of safety, efficacy, stability, and late complications. Methods: From 371 myopic eyes of 203 patients who underwent PRK using NIDEK EC-5000 excimer laser with 5.5-to 6-mm ablation zones in Basir Eye Center, Tehran, Iran, during 1997-1998, data of 179 myopic eyes of 98 patients, who participated in annual examinations, were analyzed. Treated eyes were divided into 3 groups according to preoperative refraction: low myopia [#26.00 diopters (D)], moderate myopia (26.10 to 210.00 D), and high myopia (.210.00 D). The main outcome measures were safety, efficacy, stability, and postoperative complications. Results: Eight years after PRK, 69.64%, 44.44%, and 45.65% of the low, moderate, and high myopic groups were within 60.5 D of emmetropia. Sixteen eyes (4.31% of original cases) underwent retreatment mainly because of regression. Although a small myopic shift occurred up to 8 years after surgery, changes in myopic regression stabilized in all myopic groups within 24 months. Four eyes (2.06%) lost 2 lines of best spectacle-corrected visual acuity (1 eye for corneal haze and other 3 for problems not related to refractive surgery). Corneal haze occurred in 11.34% especially in medium and high myopic groups, but it cleared within 2 years in 68.2% of cases. Conclusions: Based on our study, PRK seems to be a safe, efficient, and stable surgical procedure, and if patients obtain a good result with the initial treatment, then their results are relatively stable over time.
Clinical and Experimental Ophthalmology, 2020
Reporting outcomes of myopic photorefractive keratectomy (PRK) in a mainly ethnic Chinese population in Singapore. Background: To assess the incidence and associations of corneal haze and endothelial cell count (ECC) loss up to 12 months after PRK. Design: Retrospective case series in a tertiary eye centre. Participants: 158 patients (309 eyes) with mean age of 22.1 ± 3.4 years. Majority were Chinese (97.4%) and male (97.4%). Mean pre-operative spherical equivalent was-3.33 ± 1.15 D. Methods: Eyes were categorised based on post-operative haze severity. Multivariate analysis adjusting for age, use of intra-operative mitomycin-C (MMC), pre-operative sphere and cylinder was performed. Main Outcome Measures: Refractive outcomes and corneal haze 3 and 12 months after PRK. ECC measurements obtained before PRK and at variable periods postoperatively. Results: At 12 months, overall Efficacy Index was 0.98 and Safety Index was 1.09. 8 (2.5%) eyes underwent enhancement surgery. Analysis performed on 295 eyes which did not undergo enhancement and had complete clinical data demonstrated decrease in incidence of haze from 38.2% at 3 months to 9.3% at 12 months. Higher myopia was associated with increased haze severity at 3 months (OR, 1.36; p=0.005). Higher astigmatism was associated with increased haze severity at 3 (OR, 1.65; p=0.018) and 12 months (OR, 2.32; p=0.015). Intra-operative MMC was not associated with haze severity nor ECC loss. Conclusions and Relevance: Myopia and astigmatism were associated with increased corneal haze severity. Intra-operative MMC did not accelerate ECC loss. Overall, PRK is effective, predictable and safe in Asian eyes.
Journal of Cataract and Refractive Surgery, 2016
Background: To evaluate the safety, efficacy, and the refractive outcomes of single-step transepithelial photorefractive keratectomy (TransPRK) for the correction of mild, moderate, and high myopia. Methods: This study consecutively recruited 32 high myopic eyes, 32 mild myopic and 32 moderate myopic eyes. Eyes with myopia that had undergone TransPRK treatment. Pre-and post-operative visual and refractive data, corneal Higher Order Aberration (HOA) as well as safety and efficacy indices were analyzed at 6 months postoperatively. Results: Six months after TransPRK, the manifest refraction spherical equivalent (SE) was not significantly between high myopia group and moderate myopia group (p = 0.636). No eyes lost ≥2 lines of corrected distant visual acuity (CDVA) in high myopic eyes. The uncorrected distance visual acuity (UDVA) was significantly higher in low and moderate myopia groups than the high myopia group (P < 0.001; P = 0.002). The CDVA was not significantly different between moderate and high myopia groups (P = 0.057). There was no significant difference in mean safety index between high myopia group (1.01 ± 0.14) and mild myopia group (1.08 ± 0.15) (P > 0.05). The mean safety index was significantly higher in the moderate myopia group (1.16 ± 0.23) than in the high myopia group (1.01 ± 0.14) (P = 0.002). The efficacy index was significantly higher in the moderate myopia group (1.05 ± 0.20) than in the high myopia group (0.89 ± 0.17) (P = 0.02), and there was no significant difference between the high myopia group (0.89 ± 0.17) and the low myopia group (0.96 ± 0.16) (P = 0.14). Conclusions: The mean safety index was over 1.0 in the three groups. TransPRK showed acceptable safety and efficacy in the moderate myopic eyes, as well as mild and high myopic eyes. High myopic eyes got very similar refractive results with moderate myopic eyes six months postoperatively. The safety and efficacy indexes were not significantly different between the high myopia group and the low myopia group.
Retreatment after photorefractive keratectomy for low myopia
Ophthalmology
The purpose of the study was to evaluate the results of retreatment for low myopia after primary photorefractive keratectomy (PRK). A prospective study. A total of 48 eyes of 37 patients from 566 eyes of 331 patients originally treated for myopia of up to -6 diopters (D) were studied. Photorefractive keratectomy by the Coherent Schwind Keratom II excimer laser was performed. The parameters evaluated were visual acuity, refraction, and corneal clarity. Of the 566 eyes with myopia up to -6 D, 48 eyes (8.5%) required retreatment. The sphere (mean +/- standard deviation) was -0.88 +/- 1.24 D before second surgery. At 6 months, the mean was -0.04 +/- 0.91; at 1 year, it was -0.33 +/- 0.75 D. At 6 months, 75% of sphere value was within +/- 1 D. The preoperative uncorrected visual acuity (UCVA) was 20/200 or worse in 12.8% of eyes and 20/40 or better in 40.4% of eyes. Six months after reoperation, 20/60 UCVA was obtained in 17.4% of eyes. All others (82.6%) had UCVA of 20/40 or better, 26.1% better than 20/20. The proportion of eyes with best spectacle-corrected visual acuity better than 20/20 decreased from 60.0% to 47.1% 6 months after reoperation. Six months after reoperation, haze 1 was present in 42.9% and haze 2 in 4.7% of eyes, and in no eye was haze worse. Retreatment after PRK for low myopia can significantly increase UCVA and decrease residual refractive error without significant complications.
Ophthalmology, 1995
The Summit Therapeutic Refractive Clinical Trial is a nine-center prospective, nonrandomized, self-controlled trial to assess the efficacy, stability, and safety of using a standardized technique of excimer laser photorefractive keratectomy (PRK) to correct residual myopia in eyes with previous refractive surgery or cataract surgery. Patients and Methods: Eligible eyes with a mean residual myopia of-3.7 ± 1.8 diopters (0) (range,-0.63 to-11.00 0) underwent PRK with a 193-nm excimer laser for myopic corrections between-1.50 and-7.50 O. Standardized settings were used for the ablation zone, ablation rate, repetition rate, and fluence. One hundred seven of the first 114 treated eyes were examined 1 year after PRK, with 98% of eyes having had refractive keratotomy and 2% having had cataract surgery. Results: One year postoperatively, the mean manifest spherical equivalent refraction was-0.6 ± 1.4 0 (range,-6.50 to 2.50 0); 63% of eyes were within ±1 .00 0 of the attempted correction; and uncorrected visual acuity was 20/40 or better in 74% of eyes. Twenty-nine percent of eyes lost two or more Snellen lines of best-corrected visual acuity, and central corneal haze was moderate or severe in 8% of eyes. Conclusion: Excimer laser PRK is effective in reducing residual myopia after previous refractive and cataract surgery. However, it is less accurate than PRK in eyes that did not undergo surgery and is more likely to cause a loss of best-corrected visual acuity 1 year after treatment.
Near Point of Accommodation and Convergence after Photorefractive Keratectomy (PRK) for Myopia
Binocular Vision Strabology Quarterly Simms Romano S, 2013
Purpose: Near point of convergence (NPC) and near point of accommodation (NPA) were evaluated before and after photorefractive keratectomy (PRK) in normal myopic eyes. Methods: In this prospective cross sectional study, NPC and NPA were measured in 120 myopic eyes (60 patients) before and 3 months after PRK. Excluding criteria were manifest tropia, previous eye surgery, amblyopia, and any other ocular pathology. All subjects were younger than35 years old. Results: Fifty-one females (85%) and nine males (15%) participated in the study. The average age of the participants was 25.75 years. Before the operation, the average NPC and NPA were 4.35 cm and 6.9 cm (14.5 D), respectively. NPC and NPA increased significantly 5.63 (p = 0.025) and (p 0.05) to 7.983 cm (12.5 D) (p 0.001), respectively, after 3 months. Conclusion: NPC and NPA may increase significantly after PRK. Convergence and accommodation problems may affect near visual performance. Therefore, for any PRK candidate, accommodation and convergence should be evaluated.
Long-Term Efficacy of Photorefractive Keratectomy In Hyperopia Patients
Objective: To review the long-term efficacy, stability and reliability of photorefractive keratectomy (PRK) treatment in hyperopia patients and to assess the complications that may arise during the follow-up period. Materials and Methods: 76 eyes of 42 patients who underwent PRK treatment for hyperopia were included in this retrospective study. Patients were separated into two groups according to their spherical equivalent (SE) values. Both groups were analyzed and compared in terms of post-operative refraction and vision acuity, post-operative complications, keratometry values, stabilization period and the results of interventions for treatment. Results: Mean age of the patients was 33.97 ± 10.26 (18-51) years and the mean follow-up period was 27.16 ± 8.43 (6-39) months. Preoperative mean SE value was 1.64 ± 0.76D in group 1 and +4.45 ± 1.18D in group 2. In the last follow-up examination, those values were measured as +0.20 ± 1.01D and +1.56 ± 1.37D respectively. Uncorrected visual acuity (UCVA) of both groups were significantly higher in the last control in comparison with pre-PRK period (p=0.002 in group 1, p=0.001 in group 2). After 6 months, 92.5% of the eyes in group 1 and 85.6% of the eyes in group 2 were within ± 1.00 D range. Forty-seven (61.8%) eyes had no corneal haze meanwhile 15 (19.7%) had grade 1, 11(14.4%) had grade 2 and 3(3.9%) had grade 3 corneal haze. There was no difference in terms of haze formation between the groups (p=0.183). Conclusion: In long term, PRK treatment is an efficient, reliable and predictable method that can be used in correcting hyperopia.