Laser Assisted In Situ Keratomileusis (Lasik) Versus Trans Epithelial Photorefractive Keratectomy (T-Prk) In Astigmatic Patients (original) (raw)
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Ophthalmology, 1996
To study the efficacy of excimer laser photorefractive keratectomy (PRK) for high, moderate, and low degrees of primary myopic astigmatism. Patients and Methods: Ninety-two eyes of 54 patients with different degrees of compound myopic astigmatism underwent PRK. The eyes were divided by degree of refractive astigmatism into three groups-high (-2.75 to-5.0 diopters [D]), moderate (-1.25 to-2.50 D), and low (::s;-1.0 D). Refraction, corneal topography, slit-lamp findings, and visual acuity with and without correction were assessed. Resuns: At 12 months, the mean reduction from the preoperative refractive cylinder was 80.7% in the high astigmatism group, 68.4% in the moderate astigmatism group, and 47.6% in the low astigmatism group. The post-treatment residual cylinder axis remained stable in 23 (38.3%) of 60 eyes and deviated in 37 (61.7%) of 60 eyes. The maximal deviation of the residual cylinder axis was 15°. Of the 89.2% of eyes with low cylinder, 81.8% had moderate cylinder, and 85% of the eyes with high cylinder achieved a final uncorrected visual acuity between 20/20 and 20/35 at 12 months. Conclusions: A statistically significant reduction in the refractive cylinder was found in the high, moderate, and low astigmatism groups. The difference between the mean reduction of the high and moderate cylinders compared with the mean reduction of the low cylinders also was found to be statistically significant. The laser used in this study is an efficient tool for correcting high and moderate astigmatism. However, regarding low astigmatism, it was found to be less effective.
BMC ophthalmology, 2018
To evaluate the refractive and visual outcomes of Transepithelial photorefractive keratectomy (TransPRK) in the treatment of low to moderate myopic astigmatism. This retrospective study enrolled a total of 47 eyes that had undergone Transepithelial photorefractive keratectomy. Preoperative cylinder diopters ranged from - 0.75D to - 2.25D (mean - 1.11 ± 0.40D), and the sphere was between - 1.50D to - 5.75D. Visual outcomes and vector analysis of astigmatism that included error ratio (ER), correction ratio (CR), error of magnitude (EM) and error of angle (EA) were evaluated. At 6 months after TransPRK, all eyes had an uncorrected distance visual acuity of 20/20 or better, no eyes lost ≥2 lines of corrected distant visual acuity (CDVA), and 93.6% had residual refractive cylinder within ±0.50D of intended correction. On vector analysis, the mean correction ratio for refractive cylinder was 1.03 ± 0.30. The mean error magnitude was - 0.04 ± 0.36. The mean error of angle was 0.44° ± 7.42°...
BMC Ophthalmology, 2014
Background: This study examined the refractive and visual outcome of wavefront-optimized laser in situ keratomileusis (LASIK) in eyes with low myopia and compound myopic astigmatism ≤ 0.75 diopter (D). Methods: 153 eyes from 153 consecutive myopic patients (74 male, 79 female; mean age at surgery 40.4 ± 10.4 years) who had a preoperative refractive cylinder ≤ 0.75 D and a manifest sphere between −0.25 D and −2.75 D, and who had completed 4-month follow-up. Three subgroups defined by the magnitude of preoperative manifest refractive cylinder (0.25, 0.50, and 0.75 D) were formed. Manifest refraction, uncorrected and corrected visual acuity were assessed pre-and postoperatively. The astigmatic changes achieved were determined using the Alpins vector analysis.
BMC Ophthalmology, 2022
Background To assess transepithelial photorefractive keratectomy (tPRK) in terms of corneal epithelial healing rate, postoperative pain, postoperative discomfort, and visual and refraction outcomes compared to mechanical epithelial debridement PRK (mPRK) and alcohol-assisted PRK (aaPRK). Methods In this double-masked, randomized clinical trial, thirty-nine patients underwent tPRK in one eye and mPRK in the fellow eye (arm A), and 33 patients underwent tPRK in one eye and aaPRK in the contralateral eye (arm B). All surgical procedures were done using the Schwind Amaris excimer laser. The area of corneal epithelial defect in all eyes was captured and analyzed using ImageJ software. Results Mean epithelial healing time was respectively 3.74 ± 0.82 and 3.59 ± 0.79 days in tPRK versus mPRK ( P = 0.21) in arm A, and 3.67 ± 0.92 and 3.67 ± 0.74 days in tPRK versus aaPRK ( P = 1.00) in arm B. Accounting for the initial corneal epithelial defect area, the epithelial healing rate was faster...
Purpose: To assess the safety, efficacy and predictability of photorefractive keratectomy (PRK) [Tissuesaving (TS) versus Plano-scan (PS) ablation algorithms] of Technolas 217z excimer laser for correction of myopic astigmatism Methods: In this retrospective study one hundred and seventy eyes of 85 patients (107 eyes (62.9%) with PS and 63 eyes (37.1%) with TS algorithm) were included. TS algorithm was applied for those with central corneal thickness less than 500 µm or estimated residual stromal thickness less than 420 µm. Mitomycin C (MMC) was applied for 120 eyes (70.6%); in case of an ablation depth more than 60 μm and/or astigmatic correction more than one diopter (D). Mean sphere, cylinder, spherical equivalent (SE) refraction, uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA) were measured preoperatively, and 4 weeks,12 weeks and 24 weeks postoperatively. Results: One, three and six months postoperatively, 60%, 92.9%, 97.5% of eyes had UCVA of 20 /20 or better, respectively. Mean preoperative and 1, 3, 6 months postoperative SE were-3.48±1.28 D (-1.00 to-8.75),-0.08±0.62D,-0.02±0.57 and-0.004± 0.29, respectively. And also, 87.6%, 94.1% and 100% were within ±1.0 D of emmetropia and 68.2, 75.3, 95% were within ±0.5 of emmetropia. The safety and efficacy indices were 0.99 and 0.99 at 12 weeks and 1.009 and 0.99 at 24 weeks, respectively. There was no clinically or statistically significant difference between the outcomes of PS or TS algorithms or between those with or without MMC in either group in terms of safety, efficacy, predictability or stability. Dividing the eyes with subjective SE≤4 D and SE≥4 D postoperatively, there was no significant difference between the predictability of the two groups. There was no intra-or postoperative complication. Conclusion: Outcomes of PRK for correction of myopic astigmatism showed great promise with both PS and TS algorithms.
Journal of Optometry, 2013
To evaluate mid-term refractive outcomes and higher order aberrations of aspheric PRK for low, moderate and high myopia and myopic astigmatism with the AMARIS excimer laser system (SCHWIND eye-tech-solutions GmbH, Kleinostheim, Germany). Methods: This prospective longitudinal study evaluated 80 eyes of 40 subjects who underwent aspheric PRK. Manifest refractive spherical equivalent (MRSE) of up to −10.00 diopters (D) at the spectacle plane with cylinder up to 3.25 was treated. Refractive outcomes and corneal wavefront data (6 mm pupil to the 7th Zernike order) were evaluated out to 2 years postoperatively. Statistical significance was indicated by P < 0.05. Results: The mean manifest spherical equivalent refraction (MRSE) was −4.77 ± 2.45 (range, −10.00 D to −0.75 D) preoperatively and −0.12 ± 0.35 D (range, −1.87 D to +0.75 D) postoperatively (P < 0.0001). Postoperatively, 91% (73/80) of eyes had an MRSE within ±0.50 D of the attempted. No eyes lost one or more lines of corrected distance visual acuity (CDVA) and CDVA increased by one or more lines in 26% (21/80) of eyes. Corneal trefoil and corneal higher order aberration root mean square did not statistically change postoperatively compared to preoperatively (P > 0.05, both cases). There was a statistical increase in postoperative coma (+0.12 m) and spherical aberration (+0.14 m) compared to preoperatively (P < 0.001, both cases). Conclusion: Aspheric PRK provides excellent visual and refractive outcomes with induction in individual corneal aberrations but not overall corneal aberrations.