Single-Step Transepithelial PRK vs Alcohol-Assisted PRK in Myopia and Compound Myopic Astigmatism Correction

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.

Transepithelial Versus Epithelium-off Photorefractive Keratectomy in High Compound Myopic Astigmatism: A Contralateral Eye Study

PURPOSE

To compare clinical outcomes of transepithelial photorefractive keratectomy (t-PRK) and conventional epithelium-off PRK (PRK) in patients with high compound myopic astigmatism.

METHODS

Sixty eyes of 30 myopic individuals with at least -2.50 diopters (D) of spherical equivalent and 3.00 D of cylindrical refractive error were enrolled in the study. Both eyes of each patient were randomly assigned to either the t-PRK method or epithelium-off PRK as a matched contralateral control group. Refractive outcomes were evaluated 6 months after surgery.

RESULTS

At the 6-month visit, cylindrical refractive error magnitude was lower in the t-PRK (0.51 ± 0.29 D) compared to the PRK (0.67 ± 0.30 D) group (P = .04). The residual astigmatism was 0.50 diopters or less in 23 eyes (76%) in the t-PRK group and 15 eyes (50%) in the PRK group. In vector analysis using the Alpins method, t-PRK resulted in a significantly higher percentage of success of astigmatic surgery (84.68 ± 8.95 in t-PRK versus 79.46 ± 10.88 in PRK, P = .04). Additionally, there was a marginal advantage for the t-PRK group regarding index of success of astigmatism surgery (P = .06) and absolute (P = .08) and arithmetic (P = .07) angles of error compared to the PRK group. Both groups had an equal safety profile.

CONCLUSIONS

T-PRK is more accurate for astigmatic correction in high astigmatism than conventional PRK. Both t-PRK and PRK are comparable respecting safety and efficacy. [J Refract Surg. 2024;40(12):e956-e965.].

StreamLight Single-Step Transepithelial Photorefractive Keratectomy (PRK) for Myopia and Myopic Astigmatism

Background: To report the refractive outcomes of StreamLight transepithelial photorefractive keratectomy (PRK). Methods: A retrospective case series was conducted which included a total of 205 eyes of 109 patients who underwent StreamLight transepithelial PRK using the Alcon Wavelight EX500 excimer laser. All eyes had myopia or myopic astigmatism, and the preoperative spherical equivalent (SEQ) ranged from -0.63D to -7.25D. The primary postoperative outcomes were UDVA, CDVA and subjective refraction measured at least 3 months postoperatively. Results: Postoperatively, 196 eyes (95.6%) had a UDVA of 20/20 or better. The mean SEQ was -0.05 ± 0.31D and 189 eyes (92.2%) were within ±0.50D of the target SEQ. The mean refractive astigmatism was -0.28 ± 0.27D, and 181 eyes (88.3%) had ≤ 0.50D of astigmatism. The mean safety and efficacy indices were 1.01 ± 0.08 and 0.97 ± 0.12, respectively. Eight eyes lost 1 line of CDVA. Six of these were noted to have significant dry eyes and 2 had corneal haze. No eye lost two or more lines of CDVA. Conclusions: StreamLight transepithelial PRK results in excellent refractive outcomes for myopia and myopic astigmatism.

Factors Predicting Slow Visual Recovery Following Myopic Photorefractive Keratectomy

PURPOSE

To identify factors predicting slow visual recovery following photorefractive keratectomy (PRK).

METHODS

This retrospective study included consecutive patients who underwent PRK between January 2005 and December 2019 at Care Vision Laser Center, Tel Aviv, Israel. Myopic patients were divided into 2 groups according to whether they experienced normal recovery of visual acuity (within 60 days) or slow visual recovery (>60 days). Visual recovery was defined as achieving an efficacy index of 0.9 or greater. Efficacy index was calculated as postoperative uncorrected visual acuity/preoperative best corrected visual acuity. A comparison of baseline and intraoperative parameters was performed. Binary logistic regression was performed to identify potential predictors of slow visual recovery.

RESULTS

Overall, 4868 eyes were included. The mean age was 25.9 ± 7.7 years, and 53.9% were male. The slow visual recovery group (39.3%, n = 1911/4868) was older (P < 0.001) and had greater refractive astigmatism (P < 0.001) with a larger proportion of recent contact lens wearers (P = 0.002). The slow recovery group had larger optic zone treatments (P < 0.001), alcohol-assisted PRK (vs. transepithelial PRK) (P < 0.001), and greater maximum ablation depth (P < 0.001). In binary logistic regression, older age (P < 0.001), higher refractive astigmatism (P = 0.01), recent contact lens wear (P = 0.01), greater optic zone treatment (P = 0.001), and alcohol-assisted PRK (P < 0.001) remained significant predictors of slow visual recovery.

CONCLUSIONS

Slow visual recovery was observed in ∼40% of patients following myopic PRK. Older age, greater refractive astigmatism, recent contact lens wear, greater optic zone treatment, and alcohol-assisted PRK were associated with slow visual recovery.

Comparative outcomes of mechanical and transepithelial PRK on the same excimer laser: A contralateral eye study

PURPOSE

Compare refractive results between mechanical PRK (mPRK) and transepithelial PRK (tPRK) with WaveLight Allegretto EX500 excimer laser system (Alcon Laboratories, Fort Worth, TX, USA).

SETTING

Department of Ophthalmology of the Federal University of Sao Paulo, Brazil.

DESIGN

Prospective and randomized study.

METHODS

In 151 eyes of 73 patients with astigmatism and myopia, both eyes had similar refraction before surgery, with a maximum of 15-µm difference in ablation who underwent mPRK in one eye and tPRK in the contralateral eye. The mean age of the patients in this study was 31.45 ± 6.97 years (range, 22 to 54 years).

RESULTS

A comparison was made with all variables between the two groups, and we found that UDVA and SE were worse in the tPRK group at six months than in the mPRK group. In the mPRK group, there was a higher frequency in the +/- 0.50 range and a lower frequency in the +/- 1.50 range. In the tPRK group, however, there was a lower frequency in the +/- 0.50 range and a higher frequency in the +/- 1.50 range. Concerning gain or loss of lines of sight, there was no association between the two groups (chi-square test, p = 0.887).

CONCLUSION

Both mPRK and tPRK appear to have similar safety. However, mPRK was associated with significantly better UDVA and SE six months post-operatively.

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.

Photorefractive keratectomy in flat, normal, and steep corneas

PURPOSE

To compare photorefractive keratectomy (PRK) outcomes in patients with different corneal steepness.

SETTING

Care-Vision Laser Center, Tel-Aviv, Israel.

DESIGN

Retrospective comparative chart review.

METHODS

Patients included in this study underwent wavefront optimized myopic PRK between January 2013 and December 2019. Patients were divided into 3 groups based on the steepness of the cornea (steep keratometry) (flat: <42 diopters [D], normal: 42 to 46 D and steep: >46 D). One to one matching was performed to verify that baseline parameters (age, preoperative visual acuity and refractive error) were similar between groups. Primary outcome measures were: postoperative corrected/uncorrected distance visual acuity (CDVA/UDVA), efficacy index (postoperative UDVA/preoperative CDVA), safety index (postoperative CDVA/preoperative CDVA), spherical equivalence (SEQ) and cylinder.

RESULTS

After matching, 650 eyes were included in each group, which were similar in baseline parameters. There were no significant postoperative differences between flat, normal, and steep corneas in terms of safety index (1.02 vs 1.03 vs 1.03, P = .28), efficacy index (1.01 vs 1.01 vs 1.02, P = .57), logMAR CDVA (0.01 vs 0.02 vs 0.01, P = .76), logMAR UDVA (0.02 vs 0.03 vs 0.02, P = .68), %SEQ within 0.50 D (73.9% vs 74.2% vs 74.6%, P = .95) or 1.00 D of target (91.9% vs 92.5% vs 92.2%, P = .92), %cylinder within 0.50 D (82.8% vs 82.2% vs 81.4%, P = .81) or 1.00 D of target (96.9% vs 97.1% vs 97.2%, P = .95).

CONCLUSIONS

No significant differences were found between flat, normal and steep corneas following wavefront-optimized myopic PRK. Thus, this procedure may be safely and effectively performed in both flat and steep corneas.

Long-term results of hyperopic ablations using alcohol-assisted PRK and FS-LASIK: comparative study

PURPOSE

To evaluate the long-term visual and refractive outcomes of hyperopic excimer ablation using alcohol-assisted photorefractive keratectomy (PRK) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK).

SETTING

American University of Beirut Medical Center, Beirut, Lebanon.

DESIGN

Retrospective, matched comparative study.

METHODS

Eyes that underwent alcohol-assisted PRK were compared to matched eyes that underwent FS-LASIK. All patients were followed up for at least 3 years after surgery. The refractive and visual outcomes of each group were compared at different postoperative time points. The main outcome measures were spherical equivalent deviation from target (SEDT), manifest refraction, and visual acuity.

RESULTS

83 eyes underwent alcohol-assisted PRK and 83 matched eyes underwent FS-LASIK. Preoperative manifest refraction spherical equivalent was 2.44 ± 1.18 diopters (D) and 2.20 ± 0.87 D ( P = .133) in the PRK and FS-LASIK groups, respectively. Preoperative manifest cylinder was -0.77 ± 0.89 D and -0.61 ± 0.59 D ( P = .175) for the PRK and LASIK groups, respectively. 3 years postoperatively, SEDT was 0.28 ± 0.66 D and 0.40 ± 0.56 D for the PRK and LASIK groups, respectively ( P = .222), whereas manifest cylinder was -0.55 ± 0.49 D and -0.30 ± 0.34 D for PRK and LASIK, respectively ( P < .001). The mean difference vector was 0.59 ± 0.46 for PRK and 0.38 ± 0.32 for LASIK ( P < .001). 13.3% of PRK eyes and 0% of LASIK eyes had >1 D of manifest cylinder ( P = .003).

CONCLUSIONS

Both alcohol-assisted PRK and FS-LASIK are safe and effective for the treatment of hyperopia. PRK induces slightly more postoperative astigmatism than LASIK. Larger optical zones and recently introduced ablation profiles that lead to a smoother ablation surface might improve the clinical results of hyperopic PRK.

Transepithelial photorefractive keratectomy: a prospective randomized comparative study between the two-step and the single-step techniques

OBJECTIVES

To assess and compare the six-month outcome of the two-step transepithelial phototherapeutic keratectomy- photorefractive keratectomy (PTK-PRK) and the single-step transepithelial PRK for myopia and myopic astigmatism.

METHODS

A prospective randomized study. The study enrolled 100 eyes of 50 patients with mild to moderate myopia or myopic astigmatism stratified into two groups, PTK-PRK (n = 50 eyes) and single step PRK (n = 50 eyes). Primary outcome measures were visual acuity and manifest refraction. Secondary outcome measures were epithelial healing duration, post-PRK pain scores and 3-month postoperative haze grading.

RESULTS

Preoperative characteristics were similar in both groups (p value > 0.05). The mean uncorrected distance visual acuity (UDVA) at 1 week, 1 month, 3 and 6 months was significantly better in the single-step PRK group than in the two-step PTK-PRK group (p < 0.001). The mean manifest sphere, cylinder and spherical equivalent showed a significant difference at all follow up visits in favour of the single-step PRK (p value < 0.001). Epithelial healing duration was faster in single-step PRK (p value < 0.001). Pain scores were significantly lower following single-step PRK at 8 h, 1 day, 3 days (p value < 0.001) but were similar at the 7th day. Haze scores showed no statistical difference between the two groups at 3-month follow-up.

CONCLUSION

The two transepithelial PRK techniques were effective in correcting mild to moderate myopia and myopic astigmatism. However, Single-step transepithelial PRK achieved faster visual recovery, better refractive outcome and shorter epithelial healing time with less post-PRK pain.

CLINICAL TRIALS REGISTRY

(Clinical Trials.gov Identifier): NCT04710082.

Outcomes of Single-Step Transepithelial Photorefractive Keratectomy Compared With Alcohol-Assisted Photorefractive Keratectomy Using Wave-Light EX500 Platform

Purpose To compare the visual outcome of transepithelial photorefractive keratectomy (PRK) against alcohol-assisted PRK in treating low-to-moderate myopia with or without astigmatism. Setting Dhahran Eye Specialist Hospital, Dhahran, Saudi Arabia. Design This is a retrospective study. Methods Forty eyes of 22 patients with myopia from -0.75 to -6.00 diopters (D) with or without astigmatism from 0 to -3D were included in this study. Preoperative and postoperative data of 20 eyes from 11 patients who underwent transepithelial PRK were compared with 20 eyes from 11 patients who underwent alcohol-assisted PRK were collected and analyzed. The uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest spherical equivalence (SE), manifest cylinder, vector analysis of astigmatism, and efficacy and safety indices were compared between the groups at a mean follow-up of one year postoperatively. Results Baseline characteristics were similar between groups, except the transepithelial PRK group had lower cylinder values than the alcohol-assisted PRK group by 0.69D. Regression analysis was used to control for the difference in the cylinder in all outcome parameters. Both groups had similar mean UDVA (p=0.73), CDVA (p=0.98), the proportion of eyes in either group achieved (20/20, 20/25, and 20/30) UDVA (p=0.72, 0.68 and 0.31 respectively) and percentage of eyes lost two lines of CDVA (p=1.0). There was no statistically significant difference between the two groups in regard to both efficacy and safety indices (p=0.55 and 0.67, respectively). Both groups had similar residual SE (p=0.72), the proportion of eyes within ±0.5D of SE (p=0.29), and residual refractive astigmatism (p=0.87). Both groups had similar difference vectors, surgically induced astigmatism, and correction index (p=0.82, 0.10, and 0.26, respectively). However, the transepithelial PRK group had lower target-induced astigmatism (TIA; p=0.01), higher magnitude of error (ME; p=0.05), and higher angle of error (AE; p=0.02) than the alcohol-assisted PRK group. Conclusion Transepithelial PRK had similar visual and refractive outcomes as alcohol-assisted PRK. This approach was considered as safe and effective as alcohol-assisted PRK in treating patients with low-to-moderate myopia with or without astigmatism.

The Comparison of Intraocular Pressure Measured by Transpalpebral Method Using Diaton and Rebound Tonometry by iCare in the Eyes Before and After Transepithelial Photorefractive Keratectomy (TPRK) in Saudi Arabia

INTRODUCTION

Intraocular pressure (IOP) measurement is vital to select and monitor a patient undergoing ocular surgery. The validity of tonometry by independent researchers is useful. In this paper, we compare intraocular pressure (IOP) by rebound tonometry using iCare (Tiolat Oy, Helsinki, Finland) with transpalpebral IOP (tpIOP) method by using Diaton (Bicom Inc., NY, USA) before and after transepithelial photorefractive keratectomy (TPRK) in Saudi Arabia.

METHODS

This cross-sectional validity study was held at a private ophthalmology hospital in central Saudi Arabia from January 2021 to February 2022. The tonometry was performed before, at week 1 (W1), and month 1 (M1) after TPRK. The tpIOP and IOP by iCare were compared using matched-pair analysis. The agreement in IOP by two methods was reviewed using the Bland-Altman plot. Central corneal thickness (CCT), spherical equivalent (SE) before surgery, and gender were correlated to the difference in IOP by two tonometers. The main outcome was the difference in IOP measured by Diaton and iCare.

RESULTS

We studied 202 eyes of 101 patients. The median difference in IOP by Diaton and iCare was -1.0 mmHg before, at W1, and M1 follow-ups. Before surgery, tpIOP by Diaton was 15.0±2.8 mmHg and by iCare was 16.0±3.7 mmHg (P<0.001). At W1, tpIOP was 15.9±2.5 mmHg and 16.9±3.4 mmHg by iCare (P<0.001). At M1, tpIOP was 15.7±4.1 mmHg and 16.5±5.4 mmHg by iCare (P<0.001). IOP by two methods was within ±2 mmHg in 73.3%, 69.8%, and 75.2% of the eyes before, at W1, and M1 of TPRK. Pre-CCT (P<0.001) was the significant predictor of the difference in IOP by two methods at W1 and M1 (P=0.001). iCare gave the overestimation of IOP compared to Diaton in 18.3%, 22.8%, and 17.8% of the eyes before, W1, and M1 follow-ups.

CONCLUSIONS

IOP by iCare and Diaton was similar. Central corneal thickness was the predictor of IOP differences by tonometers.

Effect of Prophylactic Mitomycin C on Corneal Endothelium Following Transepithelial Photorefractive Keratectomy in Myopic Patients

Purpose

This study investigated the effect of prophylactic mitomycin C (MMC) on corneal endothelium to inhibit corneal haze formation post transepithelial photorefractive keratectomy (T-PRK).

Methods

A total of 120 eyes of 60 patients with low, moderate, and high myopia were subjected to T-PRK with intraoperative application of MMC (0.02%) for 30-50s. Patients' files were categorized into three groups according to ablation depths (if ≥100 µm) during T-PRK as follows: (1) Group A - low myopia without MMC, (2) Group B - low myopia with MMC, and (3) Group C - moderate/high myopia with MMC. Preoperative/surgical parameters and refractive outcomes were documented. Cell density (CD), number of cells (NUM), coefficient of variation, central corneal thickness (CCT), hexagonality (HEX/6A), average cell area (AVG), and its standard deviation (SD) were evaluated using specular microscopy preoperatively and postoperatively.

Results

Overall, 119 out of 120 eyes showed significant prevention of corneal haze. Groups A and C showed no significant changes in endothelial CD and NUM. Group B showed a non-significant reduction in CD. However, all three groups showed significant variations in HEX/6A, CCT, AVG, and SD.

Conclusion

The MMC application did not significantly affect corneal endothelial density or number and can be used safely and effectively to prevent corneal haze following T-PRK in myopia.

Transepithelial Photorefractive Keratectomy Compared to Conventional Photorefractive Keratectomy: A Meta-Analysis

This meta-analysis review compares the primary and secondary outcomes of transepithelial photorefractive keratectomy (TPRK) to the conventional photorefractive keratectomy (PRK), in terms of efficacy, predictability, safety, and patient perspectives. A total of 1711 eyes with PRK (811 eyes) and TPRK (900 eyes) from 12 studies were included through bibliographic searches. The main outcomes were efficacy, predictability, and safety parameters, and the secondary outcomes included visual and patient-reported parameters. The effect measures were weighted mean differences with 95% confidence intervals (CI) which were derived from the random-effects model of the meta-analysis to account for possible heterogeneity. TPRK procedure presents a comparable status in the main outcome and a very dominant significance in all the secondary outcomes in this meta-analysis. This study updates the evidence of the accuracy of TPRK procedure for surgical correction of all refractive errors and was deemed safer with less surgical time required and an early healing time.

Chlorhexidine and other alternatives for povidone-iodine in ophthalmic surgery: review of comparative studies

Povidone-iodine (PVI) is a universally accepted antiseptic agent used in ophthalmic surgery. Insufficient antisepsis in patients with self-reported allergies to iodine has led to devastating complications. The aim of this study was to review the current evidence for alternatives to PVI in ocular surgery. Aqueous chlorhexidine has been used as a primary antiseptic agent in Sweden for several years and has proven efficiency and safety; in a study of a large series of intravitreal injections in Australia, the endophthalmitis rates were similar to those after the use of PVI. The evidence related to using other disinfectants such as picloxydine, hypochlorous acid solution, and polyhexanide is scarce. Single studies have shown lower patient discomfort after conjunctival lavage with chlorhexidine or hypochlorous acid than with PVI. No evidence was found to suggest changing from PVI to other antiseptic agents. Disinfectant solutions other than PVI or chlorhexidine will require further investigations to show their utility in ocular surgery.

Comparison of transepithelial and conventional photorefractive keratectomy in myopic and myopic astigmatism patients: a randomized contralateral trial

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 in conventional PRK groups compared to tPRK (both P<0.001) in both arms. However, there was no significant difference in safety, efficacy, spherical equivalent refractive accuracy, or corneal haze development between tPRK and conventional PRK groups (all P > 0.05).

Conclusions

All three methods are effective in terms of visual and refractive outcomes. However, although time to complete re-epithelialization was similar with the three methods, the epithelial healing rate was faster in conventional PRK considering the initial corneal epithelial defect area, and the patients experienced less pain and discomfort in the first postoperative day.

Trial registration

IRCT, IRCT20200317046804N1. Retrospectively registered 5 May 2020.

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:

Two-Step Transepithelial Photorefractive Keratectomy with WaveLight EX500 Platform for Adolescents and Adults with Low to Moderate Myopia: A 12-Month Comparative Evaluation

Purpose

To compare the visual and refractive results obtained after two-step TransPRK using an EX500 excimer laser for low to moderate myopic correction in adolescents and adults.

Patients and Methods

Retrospectively, 91 eyes of 52 patients were categorized into four groups based on age and level of myopia. The demographics, data of efficacy, safety, predictability, stability, and post-operative complications were evaluated at 1, 3, 6, and 12 months post-operatively.

Results

At 1-month, adolescents with low myopia achieved the highest mean efficacy index (P =0.034). The efficacy indices continuously increased during the 1-year follow-up in all groups, except in adolescents with moderate myopia. The highest safety and efficacy indices were recorded in adolescents with low myopia at 1-year. Post-operative spherical equivalent within ±0.50 D at 1 year was 48.75% of all treated eyes; however, the final mean refractive spherical equivalent (MRSE) was under-corrected in all groups. By month 3, the percentage of eyes that had grade 0.5 haze was most prevalent in adolescents with moderate myopia (P <0.001).

Conclusion

two-step TransPRK using an EX500 proved to be an effective, predictable, stable and safe procedure for the correction of low to moderate myopia with or without astigmatism at 1 year. Adolescents with low myopia achieved the best-post-operative UDVA, efficacy and safety indices. Adolescents tolerated night visual problems and dry eye symptoms better than adults.

Pain response and symptoms in photorefractive keratectomy: mechanical de-epithelization compared with transepithelial ablation

PURPOSE

To compare postoperative pain and discomfort between mechanical and transepithelial photorefractive keratectomies.

METHODS

This prospective comparative study included 190 eyes of 95 patients with hyperopia (up to +4.00 D), astigmatism (up to -5.00 D), and myopia (up to -8.00 D) who underwent mechanical photorefractive keratectomy in one eye and transepithelial photorefractive keratectomy in the contralateral eye using Wavelight Allegretto EX500 excimer laser. The patients were unaware of the side treated with each technique. The interval between operations in the same patient was 15-30 days. Both eyes had similar refraction before surgery, with a maximum of 15-µm difference in ablation. Postoperative questionnaires were administered on days 1 and 7 to assess the patients' level of discomfort (0=no discomfort to 5=extreme discomfort) with the following symptoms: pain, burning sensation, itchiness, tearing, photophobia, eye redness, foreign body sensation, and eyelid swelling. Patients were also asked about which method they preferred.

RESULTS

The sample consisted of 61 women (64.21%) and 34 men (35.79%). The mean (SD) patient age was 31.66 (6.69) years (range, 22-54 years). On postoperative day 1, the patients reported significantly less discomfort in terms of pain (1.9 ± 1.74 vs 2.5 ± 1.83; p=0.017), burning sensation (1.8 ± 1.56 vs 2.5 ± 1.68; p=0.004), tearing (2.3 ± 1.71 vs 3.1 ± 1.69; p=0.001), and foreign body sensation (1.9 ± 1.77 vs 2.5 ± 1.86; p=0.024) in the eye that received mechanical photorefractive keratectomy than in the eye that received transepithelial photorefractive keratectomy. No significant differences were found between the mechanical and transepithelial photorefractive keratectomies on postoperative day 7. Fifty-nine patients (62.10%) preferred mechanical photorefractive keratectomy, while 32 (33.68%) preferred transepithelial photorefractive keratectomy. Four patients (4.22%) expressed no preference.

CONCLUSIONS

Our results showed that pain scores were significantly lower in the mechanical photorefractive keratectomy-treated eyes than in the transepithelial photorefractive keratectomy-treated eyes on postoperative day 1, which may have provided greater patient comfort after surgery and led patients to prefer the mechanical photorefractive keratectomy technique.

Effect of Bandage Contact Lens Exchange on Pain and Healing After Photorefractive Keratectomy-A Randomized Control Trial

OBJECTIVE

To evaluate the corneal re-epithelialization and patient-perceived pain after bandage contact lens (BCL) exchange on day one, after photorefractive keratectomy (PRK).

METHODS

A randomized controlled trial, of all patients who underwent bilateral transepithelial-PRK (trans-PRK) or bilateral alcohol debridement and PRK (A-PRK), between March and October 2019. One eye of each patient was randomly assigned to BCL exchange on the first postoperative day (exchange group) and the BCL was not exchanged in the fellow eye (control group). Patients were evaluated daily until healing was complete. At each visit, the corneal epithelial defect was measured, and a questionnaire was used to assess pain, photophobia, and excessive tearing. P<0.05 was statistically significant.

RESULTS

The study sample was comprised of 56 patients (mean age 27.2±5.7 years). Trans-PRK was performed in 20 (34.5%) and A-PRK in 36 (64.3%) patients. At day 3, 40 (71.4%) eyes of the exchange group healed completely compared with 38 (67.9%) eyes of the control group (P=0.5). At day-1 follow-up, the pain score was 1.87±1.4 in the exchange group and 2.29±1.3 in the control group (P=0.009). The mean pain score was 1.58±1.4 among patients who underwent A-PRK and 2.35±1.2 among patients operated by trans-PRK (P=0.04).

CONCLUSION

The epithelial healing did not vary when BCL was exchanged one day after refractive surgery. However, postoperative pain score after PRK was lower at day 1, when the BCL was exchanged. Compared with A-PRK, trans-PRK group demonstrated a higher pain score in the early postoperative phase.

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.

Three-year outcomes of mixed astigmatism correction with single-step transepithelial photorefractive keratectomy with a large ablation zone

PURPOSE

To evaluate refractive and visual outcomes of single-step transepithelial photorefractive keratectomy (transPRK) in the treatment of mixed astigmatism with the use of an aberration-neutral profile and large ablation zone.

SETTING

Nicolaus Copernicus University and Oftalmika Eye Hospital, Bydgoszcz, Poland.

DESIGN

Retrospective, observational case series.

METHODS

This study included patients who underwent transPRK to correct mixed astigmatism and completed the 3-year follow-up. Procedures were performed with an Amaris 750S excimer laser using an aberration-neutral profile and optical zone of 7.2 mm or more.

RESULTS

A total 48 eyes of 39 patients were included. Preoperatively, mean spherical manifest refraction was +1.37 ± 0.98 diopter (D) (0.25 to 4.00 D), and astigmatism was -4.00 ± 0.76 D (-2.25 to -6.00 D). Three years postsurgery, it was -0.17 ± 0.26 D and -0.41 ± 0.44 D, respectively. Attempted spherical equivalent correction within ±0.50 D was achieved in 45 eyes (94%) and cylindrical correction in 34 (71%). Preoperative corrected distance visual acuity (CDVA) was 20/20 or better in 38 eyes (79%), and postoperative uncorrected was 20/20 or better in 29 eyes (60.0%). No eye had lost 2 or more Snellen lines of CDVA, whereas 3 eyes (6%) gained 2 or more lines. In 4 eyes (8%), haze of low intensity was observed at the periphery, with scores between 0.5 and 1.0, and only 1 eye getting a score of 2 in 0- to 4-degree scale.

CONCLUSIONS

Mixed astigmatism correction with large-ablation-zone transPRK provided good results for efficacy, safety, predictability, and visual outcomes in a 3-year follow-up.

Comparison of Refractive and Visual Outcomes after Transepithelial Photorefractive Keratectomy (TransPRK) in Low versus Moderate Myopia

Is it possible to obtain good results in myopia of 2 or fewer diopters (D) with transepithelial photorefractive keratectomy (TransPRK) changing the optical zone and epithelium thickness? We retrospectively analyzed two groups of 296 eyes with a minimum follow-up of 4 months. Group A had 2 or less D, treated with an optical zone (OZ) 0.2 mm bigger than recommended, and a central epithelium thickness of 60 microns, and group B had 2 D to 5 D, with the recommended optical zone, and a 55-micron epithelium ablation at the center. The outcomes were not different between the two myopic ranges; the postop uncorrected distance visual acuity was 20/20 ± 4 in both groups (p = 0.2), which was −0.3 ± 0.8 lines worse than the preoperative corrected distance visual acuity in both groups (p = 0.5). The safety of the treatments resulted in a change of 0.0 ± 0.7 lines in the low myopia group, versus a gain of +0.1 ± 0.8 lines in the moderate myopia group (p = 0.1). The deviation from the intended target was −0.04 ± 0.33 D in the low myopia group and +0.07 ± 0.32 D in the moderate myopia group (p < 0.0001); the postoperative spherical equivalent was 0.00 ± 0.33 D in the low myopia group and +0.10 ± 0.31 D in the moderate myopia group (p < 0.0001). The postop refractive astigmatism was 0.32 ± 0.16 D in both groups (p = 0.5). In conclusion, the refractive and visual outcomes after TransPRK are comparable in low myopia changing the optical zone and epithelium thickness versus moderate myopia with standard optical zone and epithelium thickness.

Plasma Rich in Growth Factors (PRGF) in Transepithelial Photorefractive Keratectomy (TPRK)

To evaluate the usage of plasma rich in growth factor (PRGF) in transepithelial photorefractive keratectomy (TPRK) in low and moderate myopia, patients who underwent myopic and astigmatism TPRK with PRGF were involved in this retrospective, observational study. Subjects underwent a surgical procedure between February 2019 and June 2019. A three-month follow-up was recorded. Pain score was assessed with a visual analogue scale (0–10) and re-epithelialization time recorded. A total of 48 eyes from 24 patients were recruited. Mean uncorrected distance visual acuity (UDVA) was 20/20.31 (0.00 ± 0.02 LogMAR). A total of 98% of eyes did not change corrected distance visual acuity (CDVA) lines. Two percent of eyes lost one line of CDVA. Preoperative spherical equivalent was −2.67 ± 1.37 D and after three months changed to −0.21 ± 0.34 D, and 2% of eyes changed 0.50 D or more between one and three months. Pain score was 3.29 ± 0.61 (3 to 6) score points at day one and 0.08 ± 0.27 score points at day seven. Finally, re-epithelialization time was 2.50 ± 1.20 days. PRGF addition to conventional refractive treatment such as TPRK seems to alleviate immediate postoperative pain and positively contribute to corneal re-epithelization time.

Transepithelial Laser versus Alcohol Assisted Photorefractive Keratectomy Safety and Efficacy: 1-Year Follow-up of a Contralateral Eye Study

Purpose

To compare single-step transepithelial photorefractive keratectomy (TPRK) to conventional alcohol assisted epithelial removal then photorefractive keratectomy (AAPRK) regarding pain, epithelial healing, visual acuity, corneal haze measured subjectively and objectively, higher order aberrations changes, contrast sensitivity and vector analysis of astigmatic correction with one year follow-up.

Methods

A prospective double-blind randomized study of 29 subjects (58 eyes) who underwent myopic aberration-free laser correction by smart pulse technology using Schwind Amaris 1050 Hz with 1-year follow-up. Right eye was randomly treated by AAPRK or TPRK. Postoperative assessment was performed on day 1 and 3, at 1st week, and 1st, 3rd, 6th, and 12th months. Patients were assessed for pain, epithelial healing, visual acuity, corneal haze, astigmatic correction, higher order aberrations and contrast sensitivity.

Results

Epithelial healing was complete by the 3rd day in 62.1% of AAPRK eyes and in 89.7% of TPRK eyes. First day postoperative pain was higher in TPRK group (p = 0.0134). The decimal uncorrected visual acuity at 12 months was 1.47 ± 0.39 and 1.57 ± 0.38 in the AAPRK and TPRK groups respectively (p = 0.3719). Post-photorefractive keratectomy haze reached a final level of 0.04 ± 0.14 and 0.02 ± 0.1 in AAPRK and TPRK groups respectively (p = 0.5607). Contrast sensitivity was comparable in low and high frequency cycles per degree. Vector analysis of astigmatic correction showed correction index at one year of 0.99 and 1.05 for AAPRK and TPRK groups respectively.

Conclusions

Alcohol assisted and transepithelial photorefractive keratectomy have comparable results regarding safety and efficacy.

Transepithelial Photorefractive Keratektomy after a Clear Lens Exchange

PURPOSE

We evaluated the refractive visual outcomes and efficacy of Transepithelial Photorefractive Keratectomy (TransPRK) using Smart Pulse Technology with static and dynamic cyclotorsion and the AMARIS 1050 Hz RS laser platform from Schwind in the eyes after a refractive lens exchange. Setting/Venue: Aurelios Augenlaserzentrum, Recklinghausen.

METHODS

We retrospectively evaluated the data of 552 consecutive eyes treated with refractive lens exchange between 2016 and 2019. A total of 47 eyes (8.5%) required a touch up after the clear lens exchange. From 43 eyes of 43 patients, we obtained a minimum follow up of 3 months. In all cases, we performed a TransPRK with a minimum optical zone of 7.2 mm, centering the ablation on the vertex of the cornea.

RESULTS

The average age of the treated eyes was 57 years old, with a range between 48 and 68 years. The mean treated sphere was 0.42 diopters (D), with a range between -1.0 and +1.75 D. The mean astigmatism was 1.06 D. Postoperatively, after laser vision correction, we reduced the sphere to a mean of 0.11 D (range -0.5 to +0.75 D), and, postoperatively, the mean astigmatism was 0.25 D (range -0.75 to 0 D). The predictability for a spheric equivalent (SEQ) of 0.5 D was 91%, and for 1 D it was 100% of the cases. No eye lost more than one Snellen line.

CONCLUSIONS

TransPRK with smart pulse was predictable for correcting ametropia after Clear Lens Surgery.

Infectious keratitis after transepithelial photorefractive keratectomy: A case report

Transepithelial photorefractive keratectomy (tPRK) promotes faster re-epithelialization which in turn can reduce the risk of infectious keratitis in the postoperative period. We present a case of a 22-year-old man with infectious keratitis in his left eye 8 days after an uneventful bilateral tPRK. A 2 mm × 5 mm anterior stromal area of corneal infiltration with a same sized overlying epithelial defect was noted at the time of presentation. His uncorrected distance visual acuity was 20/63 in his left eye. Corneal scrapings showed Bordetella bronchiseptica. The infection responded to intensive treatment with topical levofloxacin 0.5% eye drops. The final visual acuity was 20/20 in the left eye.

Photorefractive keratectomy (PRK) Prediction, Examination, tReatment, Follow-up, Evaluation, Chronic Treatment (PERFECT) protocol - A new algorithmic approach for managing post PRK haze

Purpose

The aim of this study was to discuss the possible risk factors predisposing to post photorefractive keratectomy (PRK) haze formation and develop and validate a risk scoring system, so that this could be applied to our clinical practice as an algorithmic approach.

Methods

Study was divided into 2 arms, in the retrospective arm we looked at 238 eyes of patients undergoing PRK where certain presumed risk factors from literature and clinical experience were identified and statistical significance of association was studied in the development of corneal haze. The risk scoring system was applied to the 450 eyes in the prospective arm for validation. This was then used to formulate an algorithmic approach to manage post-PRK haze.

Results

22 out of 238 eyes in the retrospective arm developed haze where risk factors such as contact lens intolerance, altered tear film break up time, meibomian gland drop out and vitamin d levels were significantly associated with post-PRK haze (p < 0.05) and these factors were identified in the prospective arm. Treatment of these modifiable factors led to a significant reduction in post-PRK haze.

Conclusion

Thus identifying and treating risk factors of haze in patients undergoing PRK could improve surgical outcomes and patient satisfaction.

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.

Comparison of Higher-Order Aberrations After Single-Step Transepithelial and Conventional Alcohol-Assisted Photorefractive Keratectomy

Objectives:

To compare the asphericity and higher-order aberration (HOA) outcomes of single-step transepithelial photorefractive keratectomy (tPRK) and conventional alcohol-assisted PRK (aaPRK) in patients with myopia and myopic astigmatism.

Materials and Methods:

Of the 108 eyes of 54 patients enrolled in the study, tPRK was performed on 54 (50%) eyes and aaPRK was performed on 54 (50%) eyes. The following parameters were compared: corrected distance visual acuity (CDVA), spherical equivalent (SE), flat and steep keratometry, intraocular pressure, central corneal thickness, asphericity, and HOAs including horizontal and vertical coma, horizontal and vertical trefoil, spherical aberration, second-order vertical coma, and aberration coefficient.

Results:

The demographic and baseline characteristics were similar between the two groups (p>0.05, for all). The aberration coefficient value was significantly lower in patients treated with aaPRK compared to patients treated with tPRK at postoperative 3 months, 6 months, and 1 year (p=0.022, p=0.019, and p=0.017, respectively). Differences in the other variables were statistically insignificant (p>0.05 for all).

Conclusion:

Both tPRK and aaPRK procedures obtain similar postoperative CDVA, SE, asphericity, and HOA outcomes, except the aberration coefficient value.

5-year efficacy of all surface laser ablation with cross-linking (ASLA-XTRA) for the treatment of myopia

Background

The purpose of our study is to examine the long (5-year) efficacy of the all surface laser ablation (ASLA) combined with accelerated cross-linking (CXL) for the treatment of myopia without the use of mitomycin-C (MMC).

Methods

This retrospective study consisted of 202 eyes of 118 myopic (SD: 2.41, range: − 1.50 to − 12.75 D) patients (44 males, 74 females). Mean age was 28.50 years (SD: 6.45, range: 18 to 51 years) that underwent ASLA with accelerated CXL for the treatment of their myopia.

Results

The patients underwent routine postoperative assessment on the 1st, 3rd, 7th day and in the 1st, 3rd, 6th and 12th month, 30th month (±6 months), 4th and 5th year. The mean spherical equivalent (SEq) refractive error changed from − 6.41 ± 2.41 D preoperatively to − 0.02 ± 0.53 D at 5 years postoperatively. The haze score was 0.18, 0.25 and 0.28 at 1, 3 and 6 months postoperatively. At 12 months after the treatment, no eyes had significant corneal haze and in all the following postoperative time intervals the haze traces were gone.

Conclusion

ASLA combined with accelerated CXL (ASLA-XTRA) appears to be safe, efficacious and offering very good refractive results. The potential additional benefits of this modality are the stabilizing effect of the refraction and its sterilization effect on the treated cornea without the potential side effects of MMC.

Comparison of single-step transepithelial photorefractive keratectomy and conventional photorefractive keratectomy in low to high myopic eyes

Purpose

To compare the visual outcome, safety, safety index, efficacy, efficacy index and corneal transparency between single-step transepithelial photorefractive keratectomy (t-PRK) and conventional photorefractive keratectomy (PRK) with manual debridement of epithelium in eyes with low to high simple myopia and compound myopic astigmatism.

Methods

In this retrospective ,case control study, we analysed and compared the postoperative uncorrected visual acuity(UCVA), postoperative best corrected visual acuity (BCVA) , safety, safety index,efficacy,efficacy index and the corneal transparency between t-PRK and PRK with 6^th-generation Amaris excimer 500E laser (Schwind eye-tech-solutions) in 115 eyes of 59 patients.

Results

Preoperative Mean Refractive Spherical Equivalent (MRSE) was - 3.88 + 0.23 Diopters(D) and -4.73 + 0.23D in PRK and t-PRK group respectively(p=0.09). In both the groups , none of the eyes lost postoperative BCVA at the end of mean follow-up period of 3.5 months . All the eyes achieved post operative UCVA of 20/40 or better in both the groups. Incidence of trace corneal haze was high in t-PRK group at the end of 3.5 months (P = 0.003).

Conclusion

Single-step t-PRK and PRK provide similar results at the end of mean follow-up period of 3.5 months postoperatively with regards to post-operative UCVA, post operative BCVA, safety, safety index, efficacy and efficacy index. There was high incidence of trace haze in t- PRK eyes. Both the procedures are predictable, effective, and safe for correction of low to high myopia.

Wavefront properties of the anterior and posterior corneal surface after transepithelial photorefractive keratectomy in myopia

The present study aimed to evaluate the changes of corneal higher-order aberrations (HOAs) after transepithelial photorefractive keratectomy (TransPRK) in patients with myopia. A total of 80 eyes of 80 patients with myopia with or without astigmatism were evaluated. Prior to and 1 year after the surgery, uncorrected and corrected distance visual acuity in logMAR were assessed. Wavefront aberrations on the anterior surface of the cornea, as well as the posterior and total cornea, were measured via Pentacam. The HOA of the anterior surface and total values of spherical and coma aberrations increased significantly (P<0.001). However, HOAs of the anterior surface, and posterior and total values of the trefoil were not significantly changed (P=0.442, 0.805 and 0.936, respectively). A significant correlation of the pre-operative mean spherical equivalent refraction (MSER), astigmatism and central corneal ablation depth (CCAD) with the changes in coma aberration (r=0.268, P=0.016; r=0.260, P=0.020; r=0.323, P=0.004, respectively) and HOA (r=0.554, P<0.001; r=0.312, P=0.005; r=0.583, P<0.001, respectively) of the anterior surface of the cornea was determined. Furthermore, a significant correlation of the pre-operative MSER and CCAD with the changes in spherical aberration of the anterior corneal surface (r=0.462, P<0.001; r=0.510, P<0.001, respectively) was obtained. In conclusion, TransPRK offers an effective option for improving visual function in patients with myopia. The anterior corneal HOA, as well as spherical and coma aberrations, were significantly increased post-operatively. The HOA of the posterior cornea was not significantly changed. The change in the trefoil aberration was significantly correlated with pre-operative astigmatism, but the pre- and post-operative values were not significantly different.

Clinical outcomes of transepithelial photorefractive keratectomy versus femtosecond laser assisted keratomileusis for correction of high myopia in South Egyptian population

AIM

To evaluate the safety and efficacy of transepithelial photorefractive keratectomy (t-PRK) with adjuvant mitomycin C (MMC) versus femtosecond laser assisted keratomileusis (Femto-LASIK) in correction of high myopia.

METHODS

Prospective randomized comparative study including 156 eyes of 156 patients with high myopia and a spherical equivalent refraction (SER) <-6.00 D. They were divided randomly into two groups: Group A included 72 eyes treated with t-PRK with adjuvant MMC and Group B included 84 eyes treated with Femto-LASIK. Visual acuity, SER, corneal topography, pachymetry and keratometry were assessed for 12mo postoperatively.

RESULTS

The preoperative mean SER was -8.86±1.81 and -9.25±1.70 D in t-PRK MMC group and Femto-LASIK respectively (P=0.99) which improved to -0.65±0.43 D and -0.69±0.50 D at 12mo follow up. Mean SER remained stable during the 12mo of follow-up, with no statistically significant difference between the two groups (P=0.64). In t-PRK MMC group, only six eyes needed retreatment after six months of follow up. And two eyes showed haze (one reversible haze grade 2, while the other had dense irreversible haze grade 4).

CONCLUSION

t-PRK MMC provides safe and satisfactory visual outcomes and acceptable risk as Femto-LASIK in patients with high myopia.

Fellow eye comparison between alcohol-assisted and single-step transepithelial photorefractive keratectomy: late mid-term outcomes

Objective: To compare late mid-term results of two different surgical approaches of surface excimer laser ablation for myopic and astigmatic errors in contralateral eyes of the same patients. Methods: Prospective cohort study. A photorefractive keratectomy technique was performed on the right eye and single-step transepithelial photorefractive keratectomy on the left eye of the same patient, in 2012. Postoperative uncorrected and corrected visual acuities, manifest refraction, contrast sensitivity, objective scatter index, tear film stability assessed by serial measurements of objective scatter index and aberrometry as well as occurrence of haze, were compared between groups of eyes. Results: Thirty-two eyes of 16 patients with a mean time of follow-up of 35.2 +/ - 5.0 months (range 30-46 months) were evaluated. No significant differences were observed in postoperative results (visual acuity, spherical equivalent, defocus equivalent, higher-order aberrations, objective scatter index, tear film stability and contrast sensitivity). Contrast sensitivity tended to be better in transepithelial photorefractive keratectomy technique, under photopic lighting conditions without glare and mesopic conditions both with glare and without glare, however, no statistically significant differences were found. No eye presented corneal haze at the last examination. Conclusion: No statistically significant differences in visual acuity, refractive results, contrast sensitivity, objective scatter index, tear film stability or ocular aberrometry were observed between the two surface ablation techniques.

Fine tuning of the default depth and rate of ablation of the epithelium in customized trans-epithelial one-step superficial refractive excimer laser ablation

Purpose

To fine tune the default depth and rate of ablation of the epithelium in cTen™ customized trans-epithelial one-step superficial refractive surgery by the comparison between the attempted post-operative ideal corneal shape and the achieved corneal shape.

Methods

88 consecutive eyes in 64 patients undergoing trans-epithelial superficial excimer ablation using the iVis laser Suite for either myopic/astigmatic or hyperopic/astigmatic refractive error. Each patient had at least 3 months of post-operative follow-up. Topographic examination of all eyes was carried out pre-operatively and at least 3 months post-operatively using the Precisio™ surgical topographer. The comparison of these two measurements yielded values for depth, volumes and rates of ablated corneal tissue. By determining the different ablation rates of stroma and epithelium, a refinement of the depth of epithelium to be removed and a refinement of the stromal ablation were calculated.

The mathematical model was applied on each one of the 88 clinical cases and the parameters for the fine tuning of the default depth and rate of ablation of the epithelium were determined using the least squares method.

Results

The calculated pure stromal ablation rate was less than the average epithelium/stroma ablation rate used in planning the treatments by a factor of 0.96. The epithelial thickness predefined ablation assumption used to plan removal of the epithelium was adjusted considering the measured ablation and a radial adjustment function established for the fine tuning of the laser radial efficiency and allowing for the normal thickening of the epithelium in the peripheral cornea. From a clinical point of view, this methodology produces an improvement of the efficacy and a reduction of the variance of the clinical results.

Conclusion

Comparison of accurately measured pre and postoperative topographies yields accurately established ablation rates of stroma and epithelium in trans-epithelial one step superficial ablation.

Comparison of mechanical debridement and trans-epithelial myopic photorefractive keratectomy: A contralateral eye study

Purpose

To compare clinical outcomes between mechanical debridement photorefractive keratectomy (m-PRK) and trans-epithelial photorefractive keratectomy (t-PRK) in myopic patients.

Methods

Eighty eyes of 40 myopic patients with age between 18 and 55 years were included in this study. In each patient, one eye was randomly assigned for t-PRK, using the Amaris laser's ORK-CAM software and the other eye for m-PRK, using a spatula. Stromal ablation was done by Schwind Amaris 750S. Uncorrected and best corrected visual acuity (BCVA), refractive outcomes, epithelial healing, pain, and discomfort were compared between the groups on day 1, 3, 7 and month 1, 3, and 6.

Results

Preoperative spherical equivalent (SE) were −3.97 ± 2.08 diopter (D) and −3.98 ± 2.06 D in m-PRK and t-PRK eyes, respectively (P = 0.981). Operation time was significantly shorter in the t-PRK group than m-PRK (P < 0.001). Postoperative pain was experienced significantly higher in the t-PRK group measured by 11-point numeric scale of pain questionnaire on the first postoperative day (P < 0.001). Photophobia, tearing, and vision fluctuation were also significantly higher in the t-PRK group postoperatively. However epithelial defect size and re-epithelialization time were lower in the t-PRK group (P = 0.012 and P < 0.001, respectively). Postoperative parameters including SE, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and contrast acuity did not show any significant difference between the two groups during all intervals.

Conclusions

Although epithelial defect size and epithelial healing time were lower in t-PRK, postoperative pain, photophobia, and vision fluctuation were significantly less in the m-PRK group in the first postoperative days. There was no statistically significant difference between the groups after one week, and both mechanical and trans-epithelial techniques were shown to be safe and effective.

Transepithelial Photorefractive Keratectomy in Moderate to High Astigmatism With a Non-wavefront-Guided Aberration-Neutral Ablation Profile

PURPOSE

To evaluate the outcomes of transepithelial photorefractive keratectomy (PRK) in moderate to high astigmatism with a non-wavefront-guided aberration-neutral ablation profile using SmartPulse allocation.

METHODS

In this retrospective study, myopic patients with a preoperative cylinder of 2.00 diopters (D) or greater were analyzed at 3 months of follow-up. Transepithelial PRK treatments were performed in each patient with the Amaris 1050RS laser (SCHWIND eye-tech-solutions, Kleinostheim, Germany) creating aspheric ablation profiles by applying a SmartPulse allocation. Standard examinations and wavefront analyses were included for low and high ocular residual astigmatism subgroups.

RESULTS

Fifty-eight eyes (44 patients) were included in the cohort. The eyes were divided into separate ocular residual astigmatism subgroups: 17 eyes presented with less than 0.50 D (low ocular residual astigmatism) and 24 eyes with greater than 0.75 D (high ocular residual astigmatism). The mean refractive cylinder in the entire cohort was 2.84 ± 0.86 D preoperatively and 0.40 ± 0.39 D postoperatively, with 81% of the eyes within 0.75 D of the target astigmatism. At 3 months of follow-up, significant improvement (P < .05) was seen in terms of sphere, cylinder, spherical equivalent, and uncorrected (UDVA) and corrected (CDVA) distance visual acuity. CDVA improved in 40% of eyes and 3% of eyes lost one line of CDVA. No clinically relevant changes were seen in higher order aberrations. The refractive changes showed an excellent match with the keratometric changes. The difference between the low and high ocular residual astigmatism subgroups was not significant except for the change of Snellen lines of CDVA (P < .05).

CONCLUSIONS

Transepithelial PRK using a non-wavefront-guided aberration-neutral ablation profile performed by applying SmartPulse allocation yielded excellent visual outcomes. The preoperative astigmatism was reduced to subclinical values. Both subgroups were effective in terms of UDVA, CDVA, spherical and astigmatic correction, and preserving higher order aberrations. However, the low ocular residual astigmatism subgroup was slightly more prone to gain lines of CDVA. [J Refract Surg. 2018;34(7):466-474.].

Comparison of Single-Step Transepithelial Photorefractive Keratectomy With or Without Mitomycin C in Mild to Moderate Myopia

PURPOSE

To compare efficacy and safety of single-step transepithelial photorefractive keratectomy (PRK) with or without mitomycin C (MMC) in patients with mild to moderate myopia.

METHODS

Patients with mild to moderate myopia (≤ -5.50 diopters [D]) underwent single-step transepithelial PRK using the Amaris laser (SCHWIND eye-tech-solutions GmbH, Kleinostheim, Germany). Total ablation depth (epithelium and stroma) was 160 μm or less. The right eye of each patient was treated with 0.02% MMC for 10 seconds, whereas the left eye did not receive any MMC. Corneal haze, endothelial cell indices, refraction, visual acuity, contrast sensitivity, and higher order aberrations were assessed preoperatively and postoperatively.

RESULTS

In this comparative case series, 71 patients (16 men and 55 women; 142 eyes) were enrolled. Mean patient age was 27.97 ± 5.74 years. Mean preoperative spherical equivalent of patients' right and left eyes were -3.20 ± 1.20 and -3.30 ± 1.20 diopters, respectively (P = .70); other preoperative visual parameters were also comparable. Incidence of 2+ grade of haze was detected in 1 (2.5%) right and 2 (5.0%) left eyes (P > .99) 3 to 6 months postoperatively. Incidence of 1+ degree of haze was also comparable. No eye developed 3+ degrees or more of haze. One year postoperatively, both eyes achieved comparable refraction, visual acuity, contrast sensitivity, and higher order aberrations, and no greater than trace haze was detected. MMC-treated eyes suffered a greater loss of endothelial cell density (P < .001) and showed higher variance in cell size (P = .001).

CONCLUSIONS

Single-step transepithelial PRK with or without MMC showed similar efficacy and incidence of haze in eyes with mild to moderate myopia with total ablation depths of 160 μm or less. However, MMC-treated eyes showed a worse profile of endothelial cell indices. Applications of MMC in this subgroup of patients may be reconsidered. [J Refract Surg. 2018;34(6):400-407.].

Efficacy and safety of transepithelial photorefractive keratectomy

Transepithelial photorefractive keratectomy (PRK) was introduced to prevent complications from conventional PRK and femtosecond laser-assisted laser in situ keratomileusis (LASIK). In the 2-step platform, phototherapeutic keratectomy is followed by PRK. It did not show notable safety or efficacy superiorities over conventional PRK. In the conventional single-step transepithelial PRK, ablation of epithelium and stroma occurs in a single continuous session by an Amaris laser. It showed better comparative safety results. Reverse single-step transepithelial PRK and the platform using smart-pulse technology were recent improvements in the single-step Amaris laser. They provide a smoother postablative stromal bed counter. In the refined single-step platform, a modified nomogram is used for determination of ablation parameters, along with modifications in postablative measures. It yielded better comparative results in hyperopia. Controlled trials comparing reverse, smart-pulse technology-equipped, or refined platforms of single-step transepithelial PRK with other modern laser-assisted methods could provide more robust evidence on the topic. Some key elements with significant roles in post-transepithelial PRK outcomes are discussed.

Single-step Transepithelial photorefractive keratectomy in the treatment of mild, moderate, and high myopia: six month results

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.

Safety and complications after three different surface ablation techniques with mitomycin C: a retrospective analysis of 2757 eyes

BACKGROUND

To evaluate the safety and spectrum of complications of three excimer laser surface ablation techniques (SATs) with an intraoperative application of mitomycin C (MMC) 0.02%. A retrospective, non-comparative large case series.

METHODS

SATs were performed on 2757 eyes with a preoperative spherical equivalent (SE) of - 4.41 ± 2.44 and a Wavelight Allegretto 200 platform. Ablation zone diameters between 6.0 and 7.0 mm were used according to mesopic pupil size. All patients were treated with an intraoperative application of MMC for 30 to 90 s depending on refractive error. The mean follow-up time was > 3 months (107 ± 24 days). Complication range and incidence were analyzed retrospectively and safety index was calculated.

RESULTS

Two thousand seven hundred and fifty-seven eyes met the inclusion criteria for surface ablation. Two thousand five hundred and seventy-three eyes were assigned to alcohol-assisted photorefractive keratectomy (APRK), 135 eyes to transepithelial photorefractive keratectomy (TPRK), and 49 eyes to off-flap epithelial laser in situ keratomileusis (EpiLASIK/EpiK). Overall, the safety index was 1.06 ± 0.28. Haze was graded according to the Fantes scale. Haze incidence rates were highest in the TPRK group (14.81%) and comparably low in APRK (2.95%) and EpiK (4.08%) groups.

CONCLUSIONS

Intraoperative topical application of MMC (0.02%) results in good safety and no severe side effects. However, highest incidence of haze was observed after TPRK. The more frequent peripheral localization of haze might be attributed to large ablation zones and the wavefront optimized ablation profile especially in the PTK modus of the laser platform.

Visual and Refractive Outcomes After Sub-Bowman Keratomileusis and Transepithelial Photorefractive Keratectomy for Myopia

PURPOSE

To compare the visual and refractive outcomes of transepithelial photorefractive keratectomy (Trans-PRK) and sub-Bowman femtosecond-assisted laser in situ keratomileusis (SBK).

SETTING

University hospital.

DESIGN

Retrospective, comparative study.

METHODS

Two hundred forty patients with myopia and myopic astigmatism underwent SBK (n=157) or Trans-PRK (n=83). The main outcome measures included manifest spherical equivalent refraction (MRSE), logarithm of the minimum angle of resolution uncorrected visual acuity (UCVA), and best-corrected visual acuity (BCVA), which were evaluated at 1 and 3 months postoperatively.

RESULTS

The preoperative mean MRSE was -4.00±1.2 diopters (D) and -4.05±1.36 D (P=0.76) in Trans-PRK and SBK groups, respectively. There was a significant improvement in UCVA after Trans-PRK (1.29-0.00 at 1 month and -0.05 at 3 months; P<0.001 for both) and SBK (1.25 to -0.04 at 1 month and -0.05 at 3 months; P<0.001 for both). Both UCVA and BCVA were better after SBK compared with Trans-PRK at 1 month (-0.07 vs. -0.03; P<0.001) but not at 3 months (-0.08 vs. -0.07; P=0.223). The patients in Trans-PRK group were significantly more hyperopic compared with those in the SBK group at 1 month (0.11 vs. 0.04; P=0.034) and 3 months (0.11 vs. 0.04; P=0.011) postoperatively. Subgroup analysis showed that patients with myopia >3 diopters were more hyperopic at 1 month postoperatively as compared to patients with myopia of ≤3 diopters.

CONCLUSIONS

Both Trans-PRK and SBK are effective procedures to correct mild to moderate myopia and myopic astigmatism. Patients undergoing SBK experience quick visual recovery. Both procedures had no difference in visual outcomes 3 months postoperatively.

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

BACKGROUND

To compare the clinical outcomes of wavefront-optimized (WFO) transepithelial photorefractive keratectomy (trans-PRK) and corneal wavefront-guided (CWFG) trans-PRK for myopic eyes with moderate to high astigmatism.

METHODS

One hundred ninety-six eyes (196 patients) with moderate to high astigmatism (≥ 1.75 D) treated with WFO or CWFG trans-PRK (101 and 95 eyes, respectively) were retrospectively registered. Safety, efficacy, predictability, vector analysis, and corneal aberrations were compared between groups preoperatively and at 6 months postoperatively.

RESULTS

At postoperative 6 months, the mean logMAR uncorrected distance visual acuity was similar in the WFO (- 0.07 ± 0.08) and CWFG (- 0.07 ± 0.07) groups. Safety, efficacy, and predictability of refractive and visual outcomes were also similar. The correction indices were 1.02 ± 0.14 and 1.03 ± 0.13 in the WFO and CWFG groups, respectively, with no significant difference. The absolute values of the angle of error were significantly higher in the WFO group (2.28 ± 2.44 vs. 1.40 ± 1.40; P = 0.002). Corneal total root mean square higher-order aberrations and corneal spherical aberrations increased postoperatively in both groups; however, the change was smaller in the CWFG group. Corneal coma showed a significant increase postoperatively only in the WFO group.

CONCLUSIONS

WFO and CWFG trans-PRK are safe and effective for correcting moderate to high astigmatism. However, CWFG trans-PRK provides a more predictable astigmatism correction axis and fewer induced corneal aberrations.

Clinical Outcomes of SMILE With a Triple Centration Technique and Corneal Wavefront-Guided Transepithelial PRK in High Astigmatism

PURPOSE

To comparatively investigate the clinical outcomes, vector parameters, and corneal aberrations of small incision lenticule extraction (SMILE) with a triple centration technique and corneal wavefront-guided transepithelial photorefractive keratectomy (PRK) for the correction of high astigmatism.

METHODS

This retrospective, comparative case series study included 89 eyes (89 patients) that received treatment for myopia with high astigmatism (≥ 2.50 diopters) using SMILE with a triple centration technique (SMILE group; 45 eyes) and corneal wavefront-guided transepithelial PRK (transepithelial PRK group; 44 eyes). Visual acuity measurement, manifest refraction, slit-lamp examination, autokeratometry, corneal topography, and evaluation of corneal wavefront aberration were performed preoperatively and at 1, 3, and 6 months after surgery. The safety, efficacy, vector parameters, and corneal aberrations at 6 months after surgery were compared between the two groups.

RESULTS

At 6 months after surgery, the transepithelial PRK and SMILE groups exhibited comparable mean uncorrected distance visual acuities (-0.06 ± 0.07 and -0.05 ± 0.07 logMAR, respectively), safety, efficacy, and predictability of refractive and visual outcomes. There was a slight but statistically significant difference in the correction index between the transepithelial PRK and SMILE groups (0.96 ± 0.11 and 0.91 ± 0.10, respectively). Whereas the transepithelial PRK group exhibited increased corneal spherical aberration and significantly reduced corneal coma and trefoil, no changes in aberrometric values were noted in the SMILE group.

CONCLUSIONS

Both SMILE with a triple centration technique and corneal wavefront-guided transepithelial PRK are effective and provide predictable outcomes for the correction of high myopic astigmatism, although slight undercorrection was observed in the SMILE group. The triple centration technique was helpful in astigmatism correction by SMILE. [J Refract Surg. 2018;34(3):156-163.].

Clinical outcomes of Transepithelial photorefractive keratectomy to treat low to moderate myopic astigmatism

Background

To evaluate the refractive and visual outcomes of Transepithelial photorefractive keratectomy (TransPRK) in the treatment of low to moderate myopic astigmatism.

Methods

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.

Results

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°and 80.9% of eyes had axis shift within ±10°. The absolute astigmatic error of magnitude was statistically significantly correlated with the intended cylinder correction (r = 0.48, P < 0.01).

Conclusions

TransPRK showed safe, effective and predictable results in the correction of low to moderate astigmatism and myopia.

Trans advanced surface laser ablation (TransPRK) outcomes using SmartPulseTechnology

PURPOSE

To evaluate early visual rehabilitation, post-operative pain, epithelial healing and haze after transepithelial photorefractive keratectomy (TransPRK) using the SmartPulseTechnology (SPT) of Schwind Amaris (Schwind eye-tech-solutions GmbH, Kleinostheim, Germany).

METHODS

This was a retrospective comparative evaluation of a cohort of myopic patients undergoing TransPRK with SPT (group 1), with one matched control group that underwent conventional TransPRK (group 2). All cases had a 6-month post-operative follow-up including visual acuity and slit-lamp examination. Subjective evaluation of pain was recorded post-operatively.

RESULTS

49 eyes of 25 patients in group 1 and 40 eyes of 20 patients in group 2 were enrolled. The patients' visual rehabilitation was significantly faster in group 1, one day and one week post-operatively (P<0.05). From one month onward there was no significant difference between the groups. The epithelial defect size was significantly smaller on post-operative days 1 and 2 for group 1 (P<0.05 in both cases). The pain score was also significantly less in group 1 (P<0.05). The haze level had no significant difference between the groups at any post-operative point (P>0.05).

DISCUSSION

TransPRK using SPT provides promising results in the early post-operative period. Visual rehabilitation, re-epithelialization and pain were faster in the early post-operative period in group 1 in comparison with group 2. Haze formation was not significantly different between the two groups; however, it was consistently less in group 1.