Comparison between Wavefront-optimized and corneal Wavefront-guided Transepithelial photorefractive keratectomy in moderate to high astigmatism

Merging Photorefractive Keratectomy and Collagen Crosslinking: An Analysis of Literature and a Guide to Prevalent Protocols

PURPOSE

The purpose of this review was to summarize the different surgical approaches combining photorefractive keratectomy (PRK) and corneal crosslinking (CXL), present each protocol template in a simple format, and provide an overview of the primary outcomes and adverse events.

METHODS

A literature review was conducted as outlined by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Eight different databases were searched. Papers were included if PRK was immediately followed by CXL.

RESULTS

Thirty-seven papers met the inclusion criteria of a total yield of 823. The latest research into simultaneous PRK and CXL has been shown to not only stabilize the cornea and prevent keratoconus progression but also improve the visual acuity of the patient. Improvements in uncorrected distance visual acuity and (spectacle) corrected distance visual acuity were found to be significant when considering all protocols. There were also significant reductions in K1, K2, mean K, Kmax, sphere, cylinder, and spherical equivalent. Random-effects analysis confirmed these trends. Corrected distance visual acuity was found to improve by an average of 0.18 ± 1.49 logMAR (Cohen's D [CD] 0.12; P <0.02). There was also a significant reduction of 2.57 ± 0.45 D (CD 5.74; P <0.001) in Kmax. Cylinder and spherical equivalent were also reduced by 1.36 ± 0.26 D (CD 5.25; P <0.001) and 2.61 ± 0.38 D (CD 6.73; P <0.001), respectively.

CONCLUSIONS

Combining the 2 procedures appears to be of net benefit, showing stabilization and improvement of ectatic disease, while also providing modest gains in visual acuity. Since customized PRK and CXL approaches appear superior, a combination of these would likely be best for patients.

Comparison between a new transepithelial PRK vs. conventional alcohol-assisted PRK: Corneal densitometry and aberrometry study

PURPOSE

To describe and compare corneal densitometry, subjective refraction, visual acuity, and corneal higher order aberrations (HOA) after corneal refractive surgery using either alcohol-assisted photorefractive keratectomy (aaPRK) or single-step transepithelial PRK (tPRK).

METHODS

We conducted a retrospective and observational study. We analyzed 120 right eyes from 120 healthy consecutive myopic patients who underwent aaPRK or tPRK to correct myopia of up to 6 diopters and astigmatism of up to 2 diopters. The WaveLight EX500 excimer laser (Alcon Laboratories, Inc.) was used in all cases. Visual acuity, subjective refraction, and Pentacam AXL® measurements were performed at the preoperative visit and at 6-months follow-up visit. Pentacam AXL® software was used to assess corneal optical density in various annuli for different corneal depths and anterior corneal HOA (6 mm area of analysis).

RESULTS

Preoperative spherical equivalent values were similar between groups preoperatively (-3.07 ± 1.52 and -3.38 ± 1.46 in the aaPRK and tPRK groups, respectively). There were no statistically significant differences in visual acuity and postoperative refraction between groups. Postoperative corneal densitometry did not show statistically significant differences in any of the areas studied and both surgical procedures obtained similar results. However, analysis of HOA showed statistically significant differences between the techniques (1.42 ± 0.39 and 1.80 ± 0.62 for the aaPRK and tPRK groups, respectively; p = 0.000).

CONCLUSIONS

Both aaPRK and single-step tPRK gave comparable visual, refractive, and corneal density outcomes. Some differences were observed in HOA but were not clinically relevant.

Epithelial thickness map-adjusted transepithelial photorefractive keratectomy for treatment of myopic astigmatism: 12-month results

PURPOSE

To evaluate the refractive results of Transepithelial Photorefractive Keratectomy (t-PRK) with the Technolas Teneo2 Excimer laser platform.

METHODS

In this retrospective comparative interventional case series, a total of 199 patients with myopia ranging from - 1 to - 7 diopters were enrolled and separated into three groups based on their target refraction of zero (group 1), - 0.25 (group 2), and - 0.5 diopters (group 3), respectively. The main outcome measure was post-operative cycloplegic refraction. Trans-PRK was performed using the Technolas Teneo2 Excimer laser. To prevent any remaining epithelium during stromal ablation, we adopted the thickest epithelial point in the 7 mm central map as the reference for Phototherapeutic keratectomy (PTK) depth. Patients were examined three and twelve months after the procedure, and the results were analyzed.

RESULTS

At the 12-month follow-up, uncorrected distance visual acuity was 20/20 in all patients. However, there was a significant difference in cycloplegic spherical equivalent refraction between the three groups. The 12-month post-operative spherical equivalent refraction was 0.90 ± 0.33 D, 0.79 ± 0.26 D, and 0.60 ± 0.19 D in groups 1, 2, and 3, respectively (P < 0.001; Kruskal-Wallis test). The rates of spherical equivalent refraction of more than 0.75 D were 58.3%, 39.1%, and 9.1% in the 0 D, - 0.25 D, and -0.50 D groups, respectively (P < 0.001; Chi-squared test).

CONCLUSIONS

The t-PRK with Technolas Teneo2 Excimer laser and epithelial thickness map adjustment of PTK induce a significant amount of residual hyperopia (> 0.75 D) in a large proportion of eyes with a target refraction of 0 or - 0.25, which is significantly reduced by using a target refraction of - 0.5.

Twelve-month outcomes of a new refractive lenticular extraction procedure

BACKGROUND

To evaluate the 12-month refractive and visual outcomes of Small Incision Guided Human-cornea Treatment (SmartSight®, SCHWIND eye-tech-solutions, Kleinostheim, Germany) in the treatment of myopia corrections with low to moderate astigmatism with the use of a new femtosecond laser system.

METHODS

221 eyes of 114 patients consecutively treated with SmartSight lenticule extraction were assessed. The mean age of the patients was 28±6 years at the time of treatment with a mean spherical equivalent refraction of -6.26±2.17D and mean astigmatism of 0.92±0.68D. Monocular corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA) were assessed pre- and post-operatively. Refractive changes have been determined in terms of changes in refraction, as well as changes in keratometric readings. The changes in central epithelial thickness have been determined.

RESULTS

At twelve months post-operatively, mean UDVA was 20/21±2. Spherical equivalent showed a residual refraction of +0.48±0.31D with refractive astigmatism of 0.13±0.18D postoperatively. There was a slight decrease of -0.1 Snellen lines at 12-months follow-up. The same correction was determined using changes in refraction, as well as changes in keratometric readings. The central epithelial thickness increased by +3±2µm. Spherical equivalent correction within ±0.50D was achieved in 199 eyes (90%), and cylindrical correction in 221 (100%). Preoperative corrected distance visual acuity (CDVA) was 20/20 or better in 213 eyes (96%), and postoperative uncorrected (UDVA) was 20/20 or better in 205 eyes (93%). No eye had lost two or more Snellen lines of CDVA.

CONCLUSIONS

Myopic astigmatism correction with SmartSight provided good results for efficacy, safety, predictability, and visual outcomes at the twelve months of follow up. The central epithelial thickness barely increased by 3±2µm.

Comparison of Long-Term Visual and Refractive Results of Transepithelial and Mechanical Photorefractive Keratectomy

Objectives

The aim of the study was to present and compare 2 years results of mechanical photorefractive keratectomy (M-PRK) and transepithelial photorefractive keratectomy (T-PRK) for myopia.

Methods

One hundred and nine eyes of 55 patients were included in this retrospective study. The mean age of the patients was 26.9±5.2 years. Forty-four eyes (40.4%) had M-PRK and 65 eyes (59.6%) had T-PRK. Follow-up time was 2 years. Refractive errors (RE), uncorrected visual acuity (UCVA), and high-order corneal aberrations were compared.

Results

The mean RE was -2.33±0.88 D and the mean UCVA was 0.24±0.17 logMAR at baseline for M-PRK patients. At month 24, those measurements were changed to -0.27±0.32 D and 0.99±0.04 logMAR. The mean RE was 2.19±0.73 D and the mean UCVA was 0.23 ± 0.15 logMAR at baseline for T-PRK patients. At month 24, those measurements were changed to -0.14±0.32 D and 0.99±0.01 logMAR. The mean REs significantly decreased and the mean UCVA significantly increased after both type of surgeries (all p<0.001). In M-PRK group, 4 mm zone total corneal aberration and 6 mm total-coma-spherical corneal aberrations were statistically significantly increased in post-operative term. In T-PRK group, only 6 mm total-spherical corneal aberrations were statistically significantly increased in post-operative term. There was no serious complication during surgeries or follow-up time.

Conclusion

M-PRK and T-PRK were a safe and effective in the treatment of myopia in 2 years term. Some high-order aberrations may be increase after those treatments.

Comparison of clinical outcomes of LASIK, Trans-PRK, and SMILE for correction of myopia

Transepithelial photorefractive keratectomy (Trans-PRK), laser-assisted in situ keratomileusis (LASIK), and small incision lenticule extraction (SMILE) are three mainstay refractive surgeries worldwide. The applicability, efficacy, safety, and predictability of these different techniques are quite similar. Trans-PRK has the strongest biostability, earliest return to normal corneal sensitivity but the longest recovery time, most uncomfortable postoperative experience, and possibility of corneal haze. LASIK possesses the fastest visual rehabilitation but the slowest corneal nerve reinnervation, and flap displacement is possibly lifelong. SMILE incurs no flap-related complications and has intermediate vision recovery time and biomechanics compared with Trans-PRK and LASIK. However, it lacks the cyclotorsion-compensation system, eye-tracking system, and customized treatment profile for high astigmatism or irregular corneal surface. This review aims to introduce the mechanisms, pros, and cons of these three types of refractive surgery. With full understanding, practitioners could advise patients on the most suitable treatment of choice.

A comparison between wavefront-optimized and wavefront-guided photorefractive keratectomy in patients with moderate-to-high astigmatism: A randomized clinical trial

Purpose:

Methods:

Results:

Conclusion:

Femtosecond LASIK for the correction of low and high myopic astigmatism

INTRODUCTION

Higher preoperative myopic astigmatism is associated with a higher probability of retreatment due to patient dissatisfaction as a result of residual cylindrical error. Nonetheless, retreatment is safe and the final clinical results are comparable to those of patients with lower preoperative astigmatism who were satisfied with the primary treatment. Our purpose is to compare the efficacy and safety of femtosecond LASIK (FS-LASIK) for the refractive correction of patients with low (< 1.5 Diopters (D) versus high (≥ 1.5 D) myopic astigmatism.

METHODS

Retrospective observational study of 841 eyes of 825 eligible patients treated with FSLASIK for the correction of simple or compound myopic astigmatism. Outcome measures included residual error, best corrected and uncorrected distance visual acuity (BCVA and UCVA), efficacy and safety 3 months after the primary procedure or the retreatment.

RESULTS

Of 841 eyes in total, 432 (51.37%) had < 1.5 D (Group 1) and 409 (48.63%) had ≥ 1.5 D (Group 2) preoperative myopic astigmatism. The efficacy index of primary treatment was 0.94 ± 0.18 in Group 1 and 0.89 ± 0.22 in Group 2 (P = 0.001). Of 138 eyes (16.41%) that were retreated due to dis-satisfaction related to residual refractive error, 28 belonged to Group 1 (6.5%) and 110 (26.9%) to Group 2 (P < 0.001). Following retreatment, small but statistically significant differences in the residual mean postoperative cylinder (-0.08 ± 0.24 vs -0.27 ± 0.46 D, P = 0.001) and UCVA (1.11 vs 0.96, P = 0.0001) were detected for Groups 1 and 2, respectively. However, there were no statistically significant differences in the safety and efficacy indices.

CONCLUSION

Following FS-LASIK, eyes with myopic astigmatism ≥ 1.5 D have approximately four times more chances of undergoing retreatment due to dis-satisfaction caused by residual refractive error compared to eyes with myopic astigmatism < 1.5 D. However, the clinical results after retreatment are highly satisfactory and comparable in both groups.

Efficacy, safety, and predictability of transepithelial photorefractive keratectomy: meta-analysis

PURPOSE

To evaluate the efficacy, safety, and predictability of transepithelial photorefractive keratectomy (TransPRK) for correcting myopia, astigmatism, and hyperopia.

SETTING

Department of Ophthalmology, Saarland University Medical Center, Homburg/Saar, Germany.

DESIGN

Meta-analysis of retrospective or prospective studies.

METHODS

Relevant studies were collected from Medline and included when meeting the following predefined criteria: randomized controlled trials, at least 1 of the main outcome measures as efficacy, safety, or predictability, and 1 common TransPRK laser (Schwind Amaris). The parameters estimates and 95% CI were derived from random-effects meta-analysis to account for possible heterogeneity.

RESULTS

Because hyperopia studies did not meet the inclusion criteria, the results are centered on myopia and astigmatism. Sixteen studies with a total of 1924 treated eyes were included in the meta-analysis. The mean efficacy, safety, and predictability had a probability of 94% (CI, 0.86-0.97), 0% (CI, 0.00-0.03), and 89% (CI, 0.82-0.93), respectively. The mean correction index, difference vector, and index of success had a value of 1.01 (CI, 1.01-1.02), 0.20 (CI, 0.06-0.34), and 0.12 (CI, 0.07-0.18), respectively.

CONCLUSIONS

This summary estimate showed that TransPRK was highly effective, safe, and predictable in correcting myopia and/or astigmatism.

Comparison of clinical outcomes between vector planning and manifest refraction planning in SMILE for myopic astigmatism

PURPOSE

To compare clinical outcomes of small-incision lenticule extraction (SMILE) between manifest refraction (MR) and vector planning for myopic astigmatism with high ocular residual astigmatism (ORA).

SETTING

Yonsei University College of Medicine and Eyereum Eye Clinic, Seoul, South Korea.

DESIGN

Prospective, randomized, comparative case series.

METHODS

Patients with myopic astigmatism and ORA of 0.75 diopters (D) or greater were randomized into the MR or vector planning group and underwent SMILE without applying any nomogram for cylinder correction. Visual acuity, MR, corneal topography, and corneal aberration were measured preoperatively and postoperatively. Outcomes at 6 months postoperatively were compared between the groups.

RESULTS

The study comprised 114 patients (114 eyes): 58 eyes in MR planning and 56 eyes in vector planning. The mean uncorrected and corrected distance visual acuity, safety and efficacy indices were comparable between the 2 groups. Postoperative refractive cylinder reached statistically significant differences between the groups (-0.22 ± 0.18 D and -0.14 ± 0.16 D in the MR and vector planning groups, respectively, P = .02). Postoperative corneal toricity and ORA reached statistically significant lower in the vector planning group.

CONCLUSIONS

In myopic astigmatism with high ORA, MR and vector planning in SMILE were effective with comparable visual outcomes; vector planning showed statistically significant lower postoperative refractive and corneal astigmatism and ORA. Use of vector planning may improve refractive outcomes in SMILE cases with high ORA. However, the results may have been different had a nomogram adjustment been applied, as is often used for cylinder corrections with SMILE.

Three-Month Outcomes of Myopic Astigmatism Correction With Small Incision Guided Human Cornea Treatment

PURPOSE

To evaluate refractive and visual outcomes of small incision guided human cornea treatment (SmartSight; SCHWIND eye-tech-solutions) in the treatment of myopic astigmatism with the use of a new femtosecond laser system.

METHODS

This retrospective, observational case series study included 104 eyes of 56 patients who underwent SmartSight to correct myopic astigmatism and completed the 3-month follow-up. Procedures were performed with a SCHWIND ATOS femtosecond laser.

RESULTS

Preoperatively, mean manifest spherical equivalent refraction was -6.12 ± 1.99 diopters (D) (range: -3.00 to -11.50 D) and astigmatism was 1.02 ± 0.56 D (range: 0.25 to 2.75 D). Three months postoperatively, it was +0.47 ± 0.32 D (range: -0.75 to +1.00 D) and 0.27± 0.22 D (range: 0.00 to 0.75 D), respectively (both P < .05). Spherical equivalent correction within ±0.50 D was achieved in 62 eyes (60%), and cylindrical correction in 90 eyes (87%). Preoperative corrected distance visual acuity (CDVA) was 20/20 or better in 94 eyes (90%) and postoperative uncorrected distance visual acuity was 20/20 or better in 96 eyes (92%). No eye lost two or more Snellen lines of CDVA.

CONCLUSIONS

Myopic astigmatism correction with Smart-Sight provided good results for efficacy, safety, predictability, and visual outcomes in the first 3 months of follow-up. [J Refract Surg. 2021;37(5):304-311.].

Early clinical outcomes and comparison between trans-PRK and PRK, regarding refractive outcome, wound healing, pain intensity and visual recovery time in a real-world setup

PURPOSE

To compare early clinical outcomes of single-step transepithelial photorefractive keratectomy (tPRK) and photorefractive keratectomy (PRK) regarding refractive outcome, visual acuity, wound healing, pain intensity and visual recovery time.d.

METHODS

In this prospective clinical observational study 200 eyes of 100 consecutive patients with mild to moderate myopia with or without mild astigmatism were included. One hundred eyes each were either treated with StreamLight™ tPRK or PRK with the WaveLight® EX500 excimer laser. Visual acuity (Decimal) was assessed preoperatively and at day 4, 7 and 6 weeks postoperatively. Wound healing (hours between surgery and complete epithelial closure) was monitored at the slit lamp. At day 4, patients subjectively rated the maximum pain intensity within the last 4 days using a numerical pain rating scale (0-15).

RESULTS

Visual recovery was significantly faster in the tPRK group. At days 4 and 7, the mean monocular UCDVA was significantly better in the tPRK group than in the PRK group (p < 0.001). Four days after surgery 72 % of eyes in the tPRK group but no eye in the PRK had a UCDVA of 0.7 or better. At six weeks postoperatively, a UCDVA of 1.0 or better was achieved in both groups. Complete epithelial wound closure was achieved significantly faster in the tPRK group (p < 0.0001) and maximum pain level within the first 4 days after surgery was significantly lower in the tPRK group (p < 0.0001). No patient had lost a line of BCDVA and no complications or adverse effects were observed.

CONCLUSIONS

According to our early clinical results, both treatments options appear to be safe and effective methods for the correction of low to moderate myopia with and without astigmatism. However, in our study, StreamLight™ tPRK offered faster visual recovery and epithelial healing and was associated with less pain compared to PRK. It can therefore be considered a good treatment option for patients who refuse or are not eligible for Femto-LASIK, but at the same time demand a faster and more comfortable recovery time than PRK can offer.

Three-Year Outcomes of Implantable Collamer Lens Followed by Excimer Laser Enhancement ("Bioptics") in the Treatment of High Myopic Astigmatism

Purpose

Describe three-year outcomes of spherical implantable Collamer lens (ICL) followed by excimer laser enhancement (bioptics) in eyes with high myopic astigmatism.

Patients and Methods

Retrospective case series of thirty-four cases that underwent bioptics enhancement at the Johns Hopkins Wilmer Eye Institute. All eyes had a preoperative sphere of −6.00 D or more with a cylinder of at least 2.00 D. Uncorrected and corrected distance visual acuity (UDVA and CDVA), manifest spherical equivalent refraction (MSE), ICL vault measurements and central corneal thickness (CCT) were collected. Endothelial cell counts (ECC), root mean square (RMS) of higher order aberrations (HOAs), adverse events and subsequent surgeries were also assessed.

Results

All patients had a minimum follow-up of 3 years. Preoperative UDVA was 2.29 ± 0.46 logMAR and improved to 0.03 ± 0.23 logMAR at 3 years (p<0.05). MSE was −12.30 ± 4.05 preoperatively and changed to −0.21 ± 0.46 at 3 years (p<0.05). The efficacy and safety indices were 1.28 ± 0.32 and 1.47 ± 0.27 at 3 years post-enhancement. HOA did not significantly change throughout the follow-up (p<0.05). Endothelial cell loss at 12 months was calculated at 5.7%. Two eyes required ICL exchange due to vault-related issues.

Conclusion

Bioptics offered excellent long-term safe, predictable, and efficient outcomes for high myopic astigmatism and can be considered an option if toric ICL is not available. Results confirm that wavefront-guided photoablation remains an excellent option to manage residual refractive error after phakic IOL.

Refractive outcomes of high-magnitude astigmatism correction using femtosecond LASIK versus transepithelial PRK

PURPOSE

To compare the outcomes of femtosecond laser assisted in situ keratomileusis (FS-LASIK) with transepithelial photorefractive keratectomy (T-PRK) for the correction of high-grade astigmatism.

METHODS

Medical records of patients with astigmatism of 2 diopters (D) or higher, who were treated with FS-LASIK or T-PRK in 2013 through 2014 at a private practice laser clinic, were retrospectively analyzed. Efficacy, safety, predictability and vector analysis of astigmatism correction were compared between the treatment groups.

RESULTS

The study included 93 eyes treated with FS-LASIK and 186 eyes treated with T-PRK. No significant differences in postoperative spherical equivalent (-0.10 ± 0.7 D and -0.11 ± 0.7 D, respectively, p = 0.958) and postoperative refractive astigmatism (0.79 ± 0.54 D and 0.82 ± 0.63 D, respectively, p = 0.685) were demonstrated. A significant advantage of FS-LASIK over T-PRK was seen for the efficacy (1.00 ± 0.18 and 0.86 ± 0.22, respectively, p < 0.001) and safety (1.03 ± 0.17 and 0.89 ± 0.21, respectively, p < 0.001) indices. Results remain statistically significant in a multivariate analysis model. Vector analysis for the astigmatism correction showed no significant difference between the surgery methods in the surgically induced astigmatism, difference vector, correction index and index of success.

CONCLUSION

Both procedures demonstrated desirable post-operative SE outcomes for high-grade astigmatism correction. However, FS-LASIK achieved better results than T-PRK in the efficacy and safety parameters.

Early Corneal and Epithelial Remodeling Differences Identified by OCT Imaging and Artificial Intelligence Between Two Transepithelial PRK Platforms

PURPOSE

To analyze corneal and epithelial remodeling differences between SmartSurfACE reverse transepithelial PRK (SCHWIND eye-tech-solutions) and Streamlight (Alcon Laboratories, Inc) transepithelial PRK procedure using optical coherence tomography (OCT) and artificial intelligence (AI).

METHODS

This was a prospective, interventional, and longitudinal study. A contralateral eye study was conducted in which one eye was assigned to the SmartSurfACE group and the fellow eye was assigned to the Streamlight group. OCT was performed preoperatively and 1, 3, and 6 months after surgery. Uncorrected (UDVA) and corrected (CDVA) distance visual acuity and residual refractive error was measured only preoperatively and at 3 and 6 months. From OCT, curvature and aberrations of the air-epithelium (A-E) interface, epithelium-Bowman's layer (E-B) interface, and epithelium Zernike indices (EZI) were derived. Pain was evaluated at 1 day postoperatively using the Wong-Baker scale.

RESULTS

Both groups had similar UDVA, CDVA, residual refractive error, and changes in A-E and E-B curvatures at 3 and 6 months postoperatively (P > .05). However, many parameters indicated that the Streamlight group underwent a greater change in A-E aberrations, E-B aberrations, and EZI than the SmartSurfACE group postoperatively (P < .05). The EZI indicated a greater level of epithelial thickness distortion in the Streamlight group than in the SmartSurfACE group (P < .05). Using AI, the EZI were most indicative of remodeling differences between the two groups. Further, the pain was significantly greater at 1 day in the Streamlight group (P < .05).

CONCLUSIONS

Early remodeling differences existed because the Streamlight procedure removed a greater amount of epithelium than the SmartSurfACE procedure. However, the visual and refractive outcomes were comparable. [J Refract Surg. 2020;36(10):678-686.].

Comparison between aberration-free transepithelial photorefractive keratectomy and small incision lenticule extraction for correction of myopia and myopic astigmatism

PURPOSE

To evaluate the clinical outcomes of small incision lenticule extraction (SMILE) and aberration-free transepithelial photorefractive keratectomy (AF t-PRK) in patients with low to moderate myopic astigmatism, including visual acuity, refractive outcomes, astigmatic vector analysis and corneal aberrometric changes.

METHOD

This retrospective comparative case series study involved 110 right eyes of 110 patients who underwent either SMILE (55 eyes) or AF t-PRK (55 eyes). Visual acuity, manifest refractive error and corneal higher-order aberrations (HOAs) were measured and analyzed at baseline, 1 month and 3 months after operation. The safety and efficacy indices, and vector parameters were also compared.

RESULT

1 month postoperatively, the mean uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA) and spherical equivalent refraction (SE) were better after SMILE than AF t-PRK (logMAR UDVA,  - 0.03 ± 0.07 and  - 0.006 ± 0.07, P = 0.050; logMAR CDVA,  - 0.06 ± 0.07 and  - 0.03 ± 0.07, P = 0.043; SE,  - 0.04 ± 0.25 and 0.15 ± 0.26, P < 0.001). However, these parameters were comparable between the groups at 3 months after surgery. Residual astigmatism ≤ 0.25 diopters was observed in 74.5% and 90.9% (P = 0.023) of the eyes at one month and in 87.3% and 85.5% (P = 0.781) of the eyes at 3 months after SMILE and AF t-PRK, respectively. There were no significant differences between the groups in any of the vector parameters at 1 month or 3 months after surgery. Coma and total HOAs after SMILE were significantly higher than AF t-PRK (1 month coma, 0.49 ± 0.23 and 0.29 ± 0.15, P < 0.001; 1 month total RMS HOAs, 0.65 ± 0.20 and 0.54 ± 0.14, P = 0.001; 3 months coma, 0.50 ± 0.22 and 0.30 ± 0.17, P < 0.001; 3 months total RMS HOAs, 0.68 ± 0.20 and 0.55 ± 0.17, P < 0.001).

CONCLUSION

In this study, both SMILE and AF t-PRK were effective and comparable for correction of low to moderate myopic astigmatism. AF t-PRK group induced less coma and total HOAs than SMILE.

Clinical outcomes of mechanical and transepithelial photorefractive keratectomy in low myopia with a large ablation zone

PURPOSE

To evaluate the clinical outcomes, vector parameters, and aberrations between mechanical photorefractive keratectomy (PRK) and transepithelial PRK in eyes with low myopia.

SETTING

Yonsei University College of Medicine and Eyereum Eye Clinic, Seoul, Korea.

DESIGN

Retrospective, comparative case series.

METHODS

Eighty-four eyes of 84 patients with low myopia (≤2.00 diopters) were treated with mechanical or transepithelial PRK (41 eyes and 43 eyes, respectively), with the application of a large optical zone (OZ). Visual acuity, manifest refraction, slitlamp evaluation, autokeratometry, corneal topography, and the evaluation of corneal wavefront aberrations were measured preoperatively and at 1, 3, and 6 months after surgery. The efficacy, predictability, vector parameters, corneal aberrations, and safety at 6 months after surgery were compared between the two treatment groups.

RESULTS

The mean uncorrected distance visual acuity was comparable, at -0.13 ± 0.05 (SD) and -0.15 ± 0.05, in the mechanical and transepithelial PRK groups, respectively, at 6 months after surgery. The safety and efficacy indices, vector parameters, and aberrometric values were also comparable between the two groups. The OZ was large in both groups (7.09 ± 0.20 mm and 7.12 ± 0.27 mm in the mechanical PRK and transepithelial PRK groups, respectively), and showed no significant difference between groups. The corneal total root-mean-square higher-order aberrations and coma significantly reduced after treatment in both groups, and spherical aberrations significantly decreased after transepithelial PRK.

CONCLUSIONS

Mechanical and transepithelial PRK with a large OZ provided effective and safe outcomes for the correction of low myopia without differences in visual acuity and refractive outcomes between procedures.

Outcomes of Wavefront-Optimized Laser-Assisted In-Situ Keratomileusis and Photorefractive Keratectomy for correction of Myopia and Myopic Astigmatism over One Year Follow-Up

Background

Laser corneal refractive surgery suits, technology and nomograms are improving with time. This may improve the refractive and visual outcomes of the patients.

Objectives

To evaluate the safety, efficacy, stability, and predictability of wavefront-optimized photorefractive keratectomy and Laser-assisted in-situ keratomileusis in patients with myopia and myopic astigmatism over 1-year using WaveLight^® EX500 Excimer Laser machine.

Methods

In this prospective cohort study, refractive and visual outcomes in 596 eyes (365 patients), either having myopia or myopic astigmatism were assessed. Patients were divided into Two groups: 1) Patients who underwent PRK (53 eyes have myopia and 217 eyes have myopic astigmatism), 2) Patients who underwent LASIK (53 eyes have myopia and 273 eyes have myopic astigmatism).

Results

At 12 months postoperatively 94.3% of the myopic patients reached their preoperative best corrected distance visual acuity at the final one year follow up visit post PRK and LASIK. In patients with myopic astigmatism who underwent LASIK and PRK, 95.2%, and 96.3% of the patients reached their preoperative best corrected distance visual acuity at the final one year follow up visit post LASIK and PRK, respectively. The efficacy and safety indices were 1.00 or more for all groups with no eye lost any line of best corrected distance visual acuity.

Conclusion

Our study results confirm the excellent efficacy, safety, good predictability and stability of myopia / myopic astigmatism correction by either wavefront- optimized LASIK or PRK over 1-year follow-up without significant differences between them using the WaveLight^® EX500 excimer laser system.