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

Postoperative Pain Comparison Between Alcohol-Assisted and Transepithelial Photorefractive Keratectomy Using Nepafenac Treatment: A Novel Study

INTRODUCTION

The study aimed to compare postoperative pain between alcohol-assisted and transepithelial photorefractive keratectomy in patients who received the novel analgesic preoperative nepafenac treatment 2 days preoperatively and 3 days postoperatively. Pain, stinging, tearing, light sensitivity, and stress levels were evaluated.

METHODS

The study included a retrospective analysis of 55 patients divided into two groups: bilateral alcohol-assisted photorefractive keratectomy (aa-PRK) and transepithelial photorefractive keratectomy (transepithelial-PRK). Nepafenac was administered for pain control for all patients, with patients receiving four drops for 2 days before the surgery and 3 days postoperatively per clinical instructions. Patients completed questionnaires on the day of the surgery and for the first 5 days postoperatively. Statistical analysis was performed using XLSTAT (version 2023.1.2). t-Test was used to analyze and compare pain and symptom levels and Fisher's exact test for categorical data. p-Values less than 0.05 were considered statistically significant.

RESULTS

The study examined 55 patients (49% female) with a mean age of 25.11 ± 6.81 years who had undergone bilateral surface refractive surgery to correct myopic errors. The mean baseline standard error (SE) was -3.16 ± 2.20 D. Among these patients, 27 patients underwent aa-PRK and 28 patients underwent transepithelial-PRK. Higher levels of pain were significant in the aa-PRK group (p = 0.003). However, there was no significant difference between the groups in the average levels of stinging, tearing, or light sensation. Additionally, stress levels decreased over time in both groups, with levels becoming almost equal after 5 days, and there was no significant difference in the average stress levels between the two groups.

CONCLUSIONS

The study found that patients who underwent the transepithelial-PRK procedure had significantly lower pain levels compared with those who underwent aa-PRK after being treated with nepafenac per protocol. However, there was no significant difference between the two groups in terms of stinging, tearing, light sensation, and stress levels.

Activating transcription factor 3 (ATF3) and calcitonin gene-related peptide (CGRP) increase in trigeminal ganglion neurons in female rats after photorefractive keratectomy (PRK)-like corneal abrasion

Photorefractive keratectomy (PRK) is a type of eye surgery that involves removal of the corneal epithelium and its associated nerves, which causes intense acute pain in most people. We used a rat model of corneal epithelium removal (corneal abrasion) to examine underlying cellular and molecular mechanisms. In this study, we used immunohistochemistry of trigeminal ganglion (TG) to assess neuronal content of CGRP and ATF3, as well as orbital tightening (OT) to assess spontaneous pain behaviors. CGRP is an important neuropeptide in pain modulation and ATF3 is often used as a nerve injury marker. We found dynamic changes in CGRP and ATF3 in TG; both increased significantly at 24 h following corneal abrasion and females had a more pronounced increase at 24 h compared to males. Interestingly, there was no sex difference in OT behaviors. Additionally, the number of cells containing either CGRP or ATF3 in each animal correlate significantly with their OT behavior at the assessed timepoint. Since CGRP increased most in females, we tested the effectiveness of Olcegepant, a CGRP antagonist, at reducing OT behaviors following corneal abrasion in female rats. Olcegepant (1 mg/kg) was given prior to and again at 24 h after abrasion but did not change OT behaviors at any time over a 1-week period. Examination of CGRP and ATF3 together in TG showed that they rarely colocalized, indicating that the cells with upregulated CGRP are distinct from those responding to epithelial nerve injury. The studies also show that underlying molecular responses may be sex specific.

TFOS Lifestyle: Impact of elective medications and procedures on the ocular surface

The word "elective" refers to medications and procedures undertaken by choice or with a lower grade of prioritization. Patients usually use elective medications or undergo elective procedures to treat pathologic conditions or for cosmetic enhancement, impacting their lifestyle positively and, thus, improving their quality of life. However, those interventions can affect the homeostasis of the tear film and ocular surface. Consequently, they generate signs and symptoms that could impair the patient's quality of life. This report describes the impact of elective topical and systemic medications and procedures on the ocular surface and the underlying mechanisms. Moreover, elective procedures performed for ocular diseases, cosmetic enhancement, and non-ophthalmic interventions, such as radiotherapy and bariatric surgery, are discussed. The report also evaluates significant anatomical and biological consequences of non-urgent interventions to the ocular surface, such as neuropathic and neurotrophic keratopathies. Besides that, it provides an overview of the prophylaxis and management of pathological conditions resulting from the studied interventions and suggests areas for future research. The report also contains a systematic review investigating the quality of life among people who have undergone small incision lenticule extraction (SMILE). Overall, SMILE refractive surgery seems to cause more vision disturbances than LASIK in the first month post-surgery, but less dry eye symptoms in long-term follow up.

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.

Resveratrol increases tear production and ocular pain after corneal abrasion in male, but not female, rats using a photorefractive keratectomy model

Photorefractive keratectomy (PRK) is an alternative to LASIK and can cause intense acute pain that is often not relieved by standard treatments. To assess potential therapeutics for this type of acute pain, appropriate preclinical models are needed. We describe a preclinical corneal abrasion rat model that simulates the initial stages of PRK surgery and demonstrates similar pain and tear dysfunction as seen clinically. We used both behavioral and homeostatic assays to determine the therapeutic potential of resveratrol on pain and tear production. Studies were conducted in male and female Sprague-Dawley rats. Heptanol was applied to one eye and the superficial corneal epithelium was removed, mimicking the abrasion used in PRK. Spontaneous pain was assessed with orbital tightening (OT) scores for 7 days. Topical resveratrol increased OT scores sex-specifically in abraded males, but not females, at 72 h and 1 week after abrasion. Resveratrol increased tear production in abraded males, with no effect in abraded females. There was no correlation between OT score at 1 week and tear production measurements, demonstrating no relationship between spontaneous ocular pain and tear dysfunction in this model. These findings demonstrate the usefulness of our corneal abrasion preclinical PRK model for the assessment of ocular pain therapeutics and indicate that topical resveratrol may not be useful for managing PRK-induced pain.

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.

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.

Clinical outcomes of single-step transepithelial photorefractive keratectomy and off-flap epipolis-laser in situ keratomileusis in moderate to high myopia: 12-month follow-up

BACKGROUND

To compare the quantitative and qualitative optical outcomes of single-step transepithelial photorefractive keratectomy (TPRK) and off-flap epipolis-laser in situ keratomileusis (Epi-LASIK) in moderate to high myopia.

METHODS

In this prospective self-control study, we included patients with moderate to high myopia who were randomized to undergo TPRK in one eye and Epi-LASIK in the other eye. Twelve-month follow-up results for visual acuity, refraction, ocular high-order aberrations, contrast sensitivity, postoperative pain, epithelial healing, and haze grade were assessed.

RESULTS

A total of 64 eyes (32 patients) were enrolled in the study. More eyes completed re-epithelialization in the TPRK group than in the Off-flap Epi-LASIK group 3-4 days postoperatively, while all eyes completed re-epithelialization by 7 days. More eyes achieved a visual acuity (both UDVA and CDVA) of better than 20/20 in the TPRK group than in the Off-flap Epi-LASIK group. The ±0.50 D predictability for correction of the spherical equivalent (SE) was higher in the eyes of the TPRK group (91%) than in those of the off-flap Epi-LASIK group (80%) 12 months after surgery. No significant differences in ocular aberrations, including coma, spherical, and trefoil, were found between the two groups at 12 months. There were also no significant differences in visual acuity, contrast sensitivity, pain, and haze grading between the two groups.

CONCLUSIONS

Both TPRK and off-flap Epi-LASIK are safe, effective, and predictable treatments for moderate to high myopia with comparable surgical outcomes.

TRIAL REGISTRATION

This study was retrospectively registered on ClinicalTrial.gov ( NCT05060094 , 17/09/2021).

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.

Single-Step Transepithelial Photorefractive Keratectomy in Low to Moderate Myopia: A One-Year Follow-Up Study

Aim

To evaluate predictability, safety, efficacy, and visual outcome of StreamLight. ™ (SL.), the newly released single-step transepithelial photorefractive keratectomy platform by Alcon WaveLight™ (WL).

Methods

In this prospective cohort study, photorefractive keratectomy (PRK) was conducted on 500 eyes of 250 patients seeking myopic refractive vision correction. The new single-step transepithelial PRK method was applied, using the SL. platform installed in the WL. Ex 500 excimer laser machine. Patients were followed up to monitor intensity and duration of postoperative pain, as well as speed of epithelial healing in the early post-operative period and visual acuity, postoperative refraction and development of postoperative haze for one year post-operatively.

Results

Average pain duration was 1.5 days, and the mean pain intensity score on a scale of 0–10 was 3.74 + 1.51. Mean postoperative spherical equivalence was 0.01 ± 0.38 D, and the final postoperative uncorrected distance visual acuity (UCDVA) was 20/20 in 98% of eyes included in this study. None of the eyes lost more than one Snellen chart line or developed visually significant postoperative haze during the follow-up period.

Conclusion

The new SL. platform for transepithelial PRK is a safe, accurate platform, offering an easier early post-operative recovery, with no compromise in final visual outcome.

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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.

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.

Effect of Transepithelial Photorefractive Keratectomy without Mitomycin C in the Treatment of Femtosecond Laser In Situ Keratomileusis Corneal Flap Complications

Purpose

To assess the efficacy and safety of transepithelial photorefractive keratectomy (TPRK) without mitomycin C as treatment for femtosecond laser in situ keratomileusis (FS-LASIK) corneal flap complications.

Methods

Eight patients with corneal flap complications that occurred after FS-LASIK (five with eccentric flaps, two with buttonhole flaps, and one with a thick flap) were included in the study. Patients were treated with TPRK without mitomycin C between two weeks and twelve months after surgery. The postoperative manifest refraction, uncorrected distance visual acuity, and haze formation were assessed during six months of follow-up.

Results

The mean manifest refractive spherical and cylinder refraction was 0.16 ± 0.26 and -0.44 ± 0.33 diopters, respectively, at six months postoperatively. The uncorrected distance visual acuity was above 20/25 in all patients after six months of follow-up. No haze formation was detected.

Conclusions

TPRK without mitomycin C appears to be a safe and effective treatment for FS-LASIK corneal flap complications.

Changes in the Higher Order Ocular Aberrations and Central Corneal Thickness After T-PRK and Fs-LASIK

Introduction

Refractive surgery procedures, transepithelial photorefractive keratectomy (T-PRK), and femtosecond laser in situ keratomileusis (Fs-LASIK) are regarded as safe and efficacious methods for correcting myopia and myopic astigmatism. These two methods do not have many differences in results when treating spherical myopia while differences exist in the treatment of astigmatism correction. Vector analysis presents a powerful tool to show the real differences between these two methods regarding high ocular aberrations and central corneal thickness of treated eyes.

Aim

The aim of the study is to investigate changes in higher order ocular aberrations (HOAs) and central corneal thickness (CCT) following treatment of myopia and myopic astigmatism above -5.00DS and up to -2.00DC after either T-PRK or Fs-LASIK.

Methods

Patients (30 eyes per group) underwent T-PRK (group I) or Fs-LASIK (group II) procedure using the Schwind Amaris 750S laser. HOAs (3mm&5mm pupil) and CCT were measured objectively at pre-, 1,3 & 6 months postop in each case.

Results

Key results at 6 months were: i) mean values of trefoil (5mm pupil) were 0.092μm (sd,0.055,95% CI 0.072 to 0.112) & 0.126μm (sd,0.078,95% CI 0.098 to 0.154) in group I, and 0.088μm (sd,0.058,95% CI 0.067 to 0.109) & 0.064μm (sd,0.034,95% CI 0.052 to 0.076) in group II (P=0.001 at 6 months); ii) Changes in CTT (ΔCTT) and best spherical equivalent correction (ΔBSE) was significant in group II (ΔCCT=-26.55[ΔBSE]-14.06,R=0.486,P=0.006) but not in group I (p=0.034).

Conclusions

After T-PRK trefoil is worse than Fs-LASIK. The predictability of corneal changes is better following Fs-LASIK.

Biology of keratorefractive surgery- PRK, PTK, LASIK, SMILE, inlays and other refractive procedures

The outcomes of refractive surgical procedures to improve uncorrected vision in patients-including photorefractive keratectomy (PRK), laser in-situ keratomileusis (LASIK), Small Incision Lenticule Extraction (SMILE) and corneal inlay procedures-is in large part determined by the corneal wound healing response after surgery. The wound healing response varies depending on the type of surgery, the level of intended correction of refractive error, the post-operative inflammatory response, generation of opacity producing myofibroblasts and likely poorly understood genetic factors. This article details what is known about these specific wound healing responses that include apoptosis of keratocytes and myofibroblasts, mitosis of corneal fibroblasts and myofibroblast precursors, the development of myofibroblasts from keratocyte-derived corneal fibroblasts and bone marrow-derived fibrocytes, deposition of disordered extracellular matrix by corneal fibroblasts and myofibroblasts, healing of the epithelial injury, and regeneration of the epithelial basement membrane. Problems with epithelial and stromal cellular viability and function that are altered by corneal inlays are also discussed. A better understanding of the wound healing response in refractive surgical procedures is likely to lead to better treatments to improve outcomes, limit complications of keratorefractive surgical procedures, and improve the safety and efficiency of refractive surgical procedures.

Vector Analysis of Changes in the Higher Order Ocular Aberrations and Central Corneal Thickness After T-PRK and Fs-LASIK

Introduction:

Refractive surgery procedures, transepithelial photorefractive keratectomy (T-PRK) and femtosecond laser in situ keratomileusis (Fs-LASIK) are regarded as safe and efficacious methods for correcting myopia and myopic astigmatism. These two methods do not have much differences in results when treating spherical myopia, while some differences does exist in treatment of myopic astigmatism. Vector analysis presents powerful tool to show the real differences between these two methods regarding higher order ocular aberrations and central corneal thickness of treated eyes.

Aim:

The aim of the study is to investigate changes in higher order ocular aberrations (HOAs) and central corneal thickness (CCT) following treatment of myopia and myopic astigmatism above -5.00DS and up to -2.00DC after either T-PRK or Fs-LASIK.

Methods:

Patients (30 eyes per group) underwent T-PRK (group I) or Fs-LASIK (group II) procedure using Schwind Amaris 750S laser. HOAs (3mm&5mm pupil) and CCT were measured objectively at pre-, 1,3 & 6 months postop in each case.

Results:

Key results at 6 months were: i) mean values of trefoil (5mm pupil) were 0.092μm (sd,0.055,95% CI 0.072 to 0.112) & 0.126μm (sd,0.078,95% CI 0.098 to 0.154) in group I, and 0.088μm (sd,0.058,95% CI 0.067 to 0.109) & 0.064μm (sd,0.034,95% CI 0.052 to 0.076) in group II (P=0.001 at 6 months); ii) Changes in CCT (ΔCCT) and best spherical equivalent correction (ΔBSE) was significant in group II (ΔCCT=-26.55[ΔBSE]-14.06,R=0.486,P=0.006) but not in group I (p=0.034).

Conclusions:

After T-PRK trefoil is worse than Fs-LASIK. The predictability of corneal changes is better following Fs-LASIK. .

Vector Analysis of Visual Acuity and Refractive Outcomes of Astigmatic Corrections After T-PRK and Fs-LASIK

Introduction:

T Transepithelial photorefractive keratectomy (T-PRK) and femtosecond laser in situ keratomileusis (Fs-LASIK) are reftactive surgery methods for treating myopia and myopic astigmatism. Although T-PRK obtains similar results to Fs-LASIK with spherical myopia, it has differences in astigmatism correction. Vector analysis is a perfect tool to see the real difference between these two methods regarding astigmatic refraction and visual acuity.

Aim:

The aim of the study is to investigate changes in astigmatism and visual acuity following treatment of myopia and myopic astigmatism above -5.00DS and up to -2.00DC after either T-PRK or Fs-LASIK.

Methods:

Patients (30 eyes per group) underwent unremarkable T-PRK (group I) or Fs-LASIK (group II) using Schwind Amaris 750S laser. Astigmatic data acquired by subjective refraction were subjected to vector analysis to determine the association between surgically (SIA) and target induced (TIA) astigmatic powers and differences in axes(θ).

Results:

Key results at 6 months were: i) Mean astigmatism changed from -0.92 DC (sd ±0.49,95%CI-1.10to-0.75) to -0.38 DC (sd ±0.40,95% CI-0.52 to -0.24) in group I and -0.93DC (sd±0.55,95%CI -1.07 to -0.67) to -0.14DC (sd±0.31,95% CI-0.25 to -0.03) in group II (P=0.005 at 6 months). ii) Mean (±sd) θ was +9.7° (±19.0°) in group I and -2.2° (±15.5°) in group II (P=0.005).

Conclusion:

There was a greater mismatch between SIA and TIA powers and axes after T-PRK. T-PRK tends to induce more unwanted astigmatism. The predictability of the refractive and optical changes is better following Fs-LASIK.

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.