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PURPOSE: The purpose of this study was to compare early visual outcomes, epithelial healing, and stromal haze between transepithelial photorefractive keratectomy (Trans-PRK) using smart pulse technology (SPT) with traditional Trans-PRK. METHODOLOGY: This study is a retrospective, comparative study conducted at a private eye center in "Riyadh, Saudi Arabia," investigating myopic patients who underwent either Trans-PRK with SPT (study group) or traditional Trans-PRK (control group). The patients were assessed preoperatively and followed up at 1 week and 2 months postoperatively. The main outcomes included uncorrected distance visual acuity (UDVA), corneal haze, and corneal epithelial defect. RESULTS: This study included 501 eyes, of them, 222 eyes (44.3%) underwent Trans-PRK with SPT. The UDVA in the study group was significantly better 1 week postoperatively (P < 0.05). For the 2-month follow-up visits, there was no significant difference between the groups. Epithelium healing and stromal haze were comparable in the two groups without significant differences between them. CONCLUSION: Transepithelial photorefractive keratectomy with SPT yielded better short-term visual outcomes than traditional Transepithelial photorefractive keratectomy. [ABSTRACT FROM AUTHOR]

PURPOSE The purpose of this study was to compare early visual outcomes, epithelial healing, and stromal haze between transepithelial photorefractive keratectomy (Trans-PRK) using smart pulse technology (SPT) with traditional Trans-PRK. METHODOLOGY This study is a retrospective, comparative study conducted at a private eye center in “Riyadh, Saudi Arabia,” investigating myopic patients who underwent either Trans-PRK with SPT (study group) or traditional Trans-PRK (control group). The patients were assessed preoperatively and followed up at 1 week and 2 months postoperatively. The main outcomes included uncorrected distance visual acuity (UDVA), corneal haze, and corneal epithelial defect. RESULTS This study included 501 eyes, of them, 222 eyes (44.3%) underwent Trans-PRK with SPT. The UDVA in the study group was significantly better 1 week postoperatively (P < 0.05). For the 2-month follow-up visits, there was no significant difference between the groups. Epithelium healing and stromal haze were comparable in the two groups without significant differences between them. CONCLUSION Transepithelial photorefractive keratectomy with SPT yielded better short-term visual outcomes than traditional Transepithelial photorefractive keratectomy.

Abstract Background The primary objective of this investigation was to compare the nominal central ablation depth with the achieved central corneal stromal ablation depth after StreamLight transepithelial photorefractive keratectomy (tPRK) for myopia with WaveLight® laser by Alcon Laboratories, TX, USA. Methods This ambispective study encompassed a retrospective analysis of 40 eyes who underwent treatment for myopia and astigmatism, followed by a prospective examination conducted 6–9 months postoperatively. Pre- and postoperative Avanti spectral-domain optical coherence tomography (SD-OCT; Optovue Inc., CA, USA) provided stromal and epithelial thickness maps. The difference between pre- and postoperative central stromal thicknesses at the corneal vertex was used to calculate the achieved stromal thickness ablation depth. This value was then compared with the corresponding central nominal depth on the laser ablation planning map. Results A total of 40 eyes (OD/OS:18/22) of 40 patients (31.4 ± 9.2 years) were available for evaluation. The mean treated spherical equivalent was − 2.98 ± 1.46 D. The mean nominal and achieved central stromal ablation depths were 51.22 µm and 59.67 μm, respectively, showing a mean stromal excessive ablation of 16.50%. The mean pre- and postoperative central epithelial thicknesses were 53.74 μm and 59.31 μm, respectively, showing a mean postoperative thickness increase of 10.46%. This increase in the epithelial thickness rendered the mean postoperative pachymetry reduction to 54.11 μm, only 2.33% greater than the mean nominal ablation depth. Conclusions The study revealed a central stromal ablation 16.50% greater than the nominal ablation depth. This excessive stromal removal was largely compensated for by the increase in epithelial thickness, resulting in a mean difference between the nominal ablation depth and the achieved central corneal pachymetry reduction of only 2.33%. This significant excessive central stromal ablation must be taken into consideration in the calculation of the residual stromal thickness.

Objective To evaluate the changes in epithelial mapping using anterior segment OCT-based tomography (MS-39) after 1 week, 1, 3, and 6 months of manual versus transepithelial photorefractive keratectomy in patients with myopia and myopic astigmatism.Methods We designed, prospective, interventional paired eye study on 52 eyes who underwent photorefractive keratectomy to correct myopia and myopic astigmatism. Each eye of a participant was assigned to a different treatment group; 26 eyes underwent transepithelial Photorefractive keratectomy (transPRK) using Stream Light WaveLight E × 500were categorized as Group A “tPRK group” and 26 eyes underwent conventional PRK by manual epithelium removal and wavefront-optimized PRK using WaveLight E × 500excimer were categorized as Group B “mPRK group.” Epithelial mapping was evaluated for all cases preoperatively and postoperative for six months of follow-up.Results The postoperative central epithelial thickness increased in both groups; it was higher in group B (mPRK) with a statistically significant difference between both groups in the 1-week, 1-month (p

Objective: To evaluate the changes in epithelial mapping using anterior segment OCT-based tomography (MS-39) after 1 week, 1, 3, and 6 months of manual versus transepithelial photorefractive keratectomy in patients with myopia and myopic astigmatism. Methods: We designed, prospective, interventional paired eye study on 52 eyes who underwent photorefractive keratectomy to correct myopia and myopic astigmatism. Each eye of a participant was assigned to a different treatment group; 26 eyes underwent transepithelial Photorefractive keratectomy (transPRK) using Stream Light WaveLight E × 500were categorized as Group A "tPRK group" and 26 eyes underwent conventional PRK by manual epithelium removal and wavefront-optimized PRK using WaveLight E × 500excimer were categorized as Group B "mPRK group." Epithelial mapping was evaluated for all cases preoperatively and postoperative for six months of follow-up. Results: The postoperative central epithelial thickness increased in both groups; it was higher in group B (mPRK) with a statistically significant difference between both groups in the 1-week, 1-month (p < 0.001), and 3-month (p < 0.05) follow-up points with a mean of 57.54 µ,52.40 µ, and 55.23 µ in group A, respectively, and a mean of 65.31µ, 58.50 µ, and 57.41 µin group B, respectively. The postoperative paracentral epithelial thickness increased in both groups; it was higher in group B (mPRK) with a statistically significant difference between both groups at all postoperative follow-up points (p < 0.001) with a mean of 51.20µ, 51.12µ, 53.09µ, and 54.20 µ in group A while with a mean of 65.32µ,64.87µ,58.13µ, and 57.55µ in group B. Conclusion: Epithelial thickness mapping after PRK shows epithelial hyperplasia in both mPRK and tPRK methods with a smoother and less fluctuant course in the transepithelial treated eyes, especially in the early preoperative period. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the safety and efficacy of the transepithelial photorefractive keratectomy (TransPRK) performed using smart pulse technology (SPT) in myopic eyes with refractive error ranging from −5.25 D to −9.75 D. Methods: This retrospective study evaluated the outcomes of SPT-assisted TransPRK in 150 eyes performed using a 1050 Hz AMARIS excimer laser. Results: At 6 months postoperative, 98% of eyes achieved uncorrected distance visual acuity (UDVA) of 20/25 or better, and postoperative UDVA within one line of preoperative corrected distance visual acuity (CDVA). No eyes lost any line of CDVA. Residual spherical equivalent refraction and cylinder within ±0.50 D of intended correction were achieved in 72% and 67% of eyes, respectively. Ninety-seven percent of eyes reported no halos and glare. Conclusions: TransPRK using a 1050 Hz excimer laser with SPT showed excellent predictability, safety, and efficacy for moderate to high myopia correction. [ABSTRACT FROM AUTHOR]

AIM: To study the effect of mitomycin C (MMC) applied during transepithelial photorefractive keratectomy (TPRK) on the corneal endothelium one week (W1) and three months (M3) after surgery and its determinants. METHODS: In this two-armed cohort study conducted in 2022, eyes treated with MMC during TPRK (group 1) were compared with eyes not treated with MMC (group 2). The corneal endothelial cell (EC) count, EC density (ECD; cells/mm2), average (μm2), standard deviation (μm2), coefficient of variation (CV%), ECmax, ECmin, and EC percentage of hexagonality were estimated at W1 and M3. The postoperative changes in the EC count in the two groups were compared and correlated with the other independent variables. RESULTS: Group 1 had 26 eyes, and group 2 had 78 eyes. All TPRK indices were significantly higher for the eyes in group 1 than for those in group 2. The MMC usage was not a significant predictor of the change in ECD (P=0.644), change in CV (P=0.374), and change in the percentage of hexagonality of EC (P=0.164) at W1. However, the use of MMC was a significant predictor of changes in CV (P=0.014) and the change in the percentage of hexagonality of EC (P=0.039) at M3. The duration of laser exposure and the size of the optical zone influenced the correlation of MMC use with the changes in EC indices, postoperatively. CONCLUSION: The use of MMC doesn't affect ECD, CV, and percentage of hexagonality at W1 if other surgical indices are considered. At M3 after operating myopic eyes by TPRK, MMC significantly influence the CV and percentage of hexagonality. The duration of the laser application and the size of the optical zone should be considered when determining the effect of MMC on the EC indices.

AIM:To investigate the effect of small incision lenticule extraction(SMILE)on the treatment of myopia patients, and the impact on corneal biomechanics.METHODS:Retrospective study. A total of 120 myopic patients(240 eyes)who were scheduled to undergo corneal refractive surgery in Anyang Eye Hospital from January 2020 to December 2021 were selected. The patients were divided into SMILE group(64 patients, 128 eyes)and transepithelial photorefractive keratectomy(TransPRK)group(56 patients, 112 eyes)according to the surgical treatment method. The two groups were compared in terms of uncorrected visual acuity, corneal biomechanics, corneal endothelial cell count, posterior corneal surface height and corneal surface regularity index at 1, 7 d, 1, 3, 6 mo and 1 a after surgery, and surgical complications.RESULTS:The uncorrected visual acuity of the SMILE group at 1, 7 d and 1 mo after surgery was better than that of the TransPRK group(all P0.05). Compared with preoperative values, corneal-compensated intraocular pressure, Goldmann-correlated intraocular pressure, corneal resistance factor, and corneal hysteresis in both groups showed a first decreasing and then increasing trend after surgery. The corneal-compensated intraocular pressure, Goldmann-correlated intraocular pressure, corneal resistance factor, and corneal hysteresis in the SMILE group at 1, 7 d and 1 mo after surgery were higher than those in the TransPRK group(all P0.05). There were no significant changes of corneal endothelial cell count and corneal posterior surface height in the two groups after surgery(all P>0.05). Furthermore, corneal surface regularity index of the two groups showed a first increasing and then decreasing trend after surgery, with no statistically significant difference between the groups(P>0.05), and there was no statistically significant difference in the incidence of postoperative complications between the groups(P>0.05).CONCLUSION:Compared with TransPRK, SMILE has less influence on corneal biomechanics, and better visual recovery in the early stage. There is no difference in long-term visual acuity between the two surgeries, and both have good safety and effectiveness.

Objectives: The objective of this study was to analyze the changes in the effective optical zones (EOZ) using topographic techniques on the tangential curvature difference map at post-operative 1-year following transepithelial photorefractive keratectomy (T-PRK) and to identify parameters linked to the EOZ alterations. Methods: The study comprised 55 eyes of 55 myopic patients who underwent T-PRK. EOZs were measured using the tangential curvature difference map of the Scheimpflug tomography system. Correlations between the EOZ alterations and relevant parameters were assessed. Results: The EOZ was significantly lower than the programmed optical zone (p<0.001). The decrease in the EOZ was significantly relevant to the decrease in mean keratometry (p=0.01, B/95% confidence interval [CI]: 0.139/0.033 and 0.244, standardized Beta: 0.346) and the increase in maximum keratometry (p=0.003, B/95% CI: 0.072/0.026 and 0.118, standardized Beta: 0.406). Conclusion: The EOZ decreased in the 1st year after T-PRK in eyes with myopia. The decrease in the EOZ was correlated positively with the decrease in mean and maximum keratometry. T-PRK may be an effective and safe surgery for the correction of mild-to-moderate myopia. [ABSTRACT FROM AUTHOR]

To evaluate the safety and efficacy of Transepithelial photorefractive keratectomy (TransPRK) for hyperopia using SmartPulseTechnology (SPT). The study included 108 eyes (56 patients) with hyperopia (0.50 to 7.25 diopters [D]), with or without astigmatism (0.00 to-3.00 D), who underwent single-step transepithelial PRK with Amaris 500 -Hz excimer laser (SCHWIND eye technology) solutions, Kleinostheim, Germany). Two groups were formed as hypermetropia below three and above 3. A 6-month follow-up was performed. Preoperative and postoperative visual acuity, preoperative and postoperative manifest refraction, and postoperative corneal hase were compared. Postoperative uncorrected visual acuity (UCVA) was 0.006 ± 0.018 logmar in group 1 and 0.022±0.034 logmar in group 2. When the groups were compared, there was a statistically significant difference between preoperative and postoperative UCVA. (p [Med-Science 2023; 12(4.000): 1077-81]

Corneal epithelial healing after refractive surgery is a clinically significant issue, especially for surface ablation procedures, and this can be monitored using optical coherence tomography (OCT). The aim of this work is to investigate the corneal epithelial thickness and irregularity by OCT after transepithelial photorefractive keratectomy (t-PRK) and analyse its correlation with visual and refractive outcomes. Patients aged ≥18 years with myopia, with or without astigmatism, who underwent t-PRK between May 2020 and August 2021 were included. All participants were subjected to complete ophthalmic examinations and OCT pachymetry at every follow-up visit. Patients were followed up at 1 week and 1, 3, and 6 months postoperatively. A total of 67 patients (126 eyes) were enrolled in this study. One month postoperatively, spherical equivalent refraction and visual acuity achieved preliminary stability. However, central corneal epithelial thickness (CCET) and standard deviation of the corneal epithelial thickness (SDcet) took 3–6 months to progressive recovery. Patients with higher baseline spherical equivalent refraction were associated with slower epithelial recovery. At every follow-up time point, a significant superior-inferior difference in the minimum corneal epithelial thickness area was observed. Higher stromal haze was correlated with higher spherical equivalent refraction (both baseline and residual) but had no relation with visual outcomes. There was a significant correlation between higher CCET with a better uncorrected distance visual acuity and lower corneal epithelial thickness irregularity. CCET and SDcet measured by OCT seem to be a good auxiliary indicator for reflecting the status of corneal wound recovery after t-PRK surgery. However, a well-designed randomised control study is needed to confirm the study results. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the study was to analyze the time-savings associated with introduction of Streamlight™ (Alcon Laboratories, Fort Worth, TX, USA) transepithelial photorefractive keratectomy (PRK) in surface corneal ablations. Methods: All refractive surgeries were performed using the Alcon WaveLight® EX500 at the ArtLife Clinic, Gdańsk, Poland. The study included patients treated for refractive errors with transepithelial PRK between April 2019 and October 2021, who were matched with patients treated with alcohol-assisted PRK during the same period. Only results for the left eye were analyzed. Results: One-hundred-five patients underwent transepithelial PRK (age 33.42 ± 8.67 years) and were matched with 105 patients that underwent alcohol-assisted PRK (age 33.05 ± 10.16 years; p = 0.11). The mean preoperative spherical equivalent refraction was − 2.04 ± 2.28 D, and − 1.9 ± 1.71 D for the transepithelial and alcohol-assisted PRK group, respectively (p = 0.20). The total surgery time was non-significantly shorter in transepithelial PRK (349.46 ± 47.83 s) than in alcohol-assisted PRK (354.93 ± 137.63 s; p = 0.7); however, the variance of surgical time was significantly lower in transepithelial PRK (p < 0.001). The laser treatment duration was greater in transepithelial PRK (41.78 ± 17.2 s) than in alcohol-assisted PRK (8.48 ± 6.12 s; p < 0.001), and so was the number of breaks during the laser treatment (0.95 ± 0.63 vs. 0.53 ± 0.88, respectively; p < 0.001). Conclusion: The introduction of transepithelial PRK did not bring significant time-associated savings into the refractive surgery suite. [ABSTRACT FROM AUTHOR]

To evaluate the safety and efficacy of Transepithelial photorefractive keratectomy (TransPRK) for hyperopia using SmartPulseTechnology (SPT). The study included 108 eyes (56 patients) with hyperopia (0.50 to 7.25 diopters [D]), with or without astigmatism (0.00 to-3.00 D), who underwent single-step transepithelial PRK with Amaris 500 -Hz excimer laser (SCHWIND eye technology) solutions, Kleinostheim, Germany). Two groups were formed as hypermetropia below three and above 3. A 6-month follow-up was performed. Preoperative and postoperative visual acuity, preoperative and postoperative manifest refraction, and postoperative corneal hase were compared. Postoperative uncorrected visual acuity (UCVA) was 0.006 ± 0.018 logmar in group 1 and 0.022±0.034 logmar in group 2. When the groups were compared, there was a statistically significant difference between preoperative and postoperative UCVA. (p<0.01) The mean preoperative spherical equivalent value was 2.47±1.01 and 5.75±1.32 diopters, respectively. The mean postoperative spherical equivalent value was 0.16±0.24 and 0.32±0.27 diopters, respectively. No corneal hase was found in both group in the 6th postoperative month. There was no difference between the groups in the postoperative spherical equivalent. (p=0.374) TransPRK using SPT is promising in achieving the target refractive value in low and moderate hyperopia. This method allows patients to everyday-quickly return to normal life due to the rapid recovery process and low corneal damage rate. [ABSTRACT FROM AUTHOR]

Abstract Background In eyes with hyperopia, astigmatism, and mixed astigmatism Transepithelial photorefractive keratectomy (TransPRK) is a modality of surface ablation surgery. We center on the corneal vertex for all our treatments (all have an offset to the center of the pupil) and wanted to compare the visual results of symmetrical profile treatments versus asymmetrical profile treatments (the center of the treatment on the vertex and the boundaries with the pupil center) using TransPRK as corneal refractive surgery. Methods We retrospectively analyzed two consecutive groups of eyes treated with TransPRK in the Aurelios Augenlaserzentrum Recklinghausen: 47 eyes treated with symmetrical offset and 51 eyes treated with asymmetrical offset. The intergroup comparisons were assessed using unpaired Student’s T-tests, whereas preoperative to postoperative changes were assessed using paired Student’s T-tests. Results Refractive outcomes were good for both groups. 83 and 88% of eyes were within the spherical equivalent of 0.5 D from the target in the symmetric and asymmetric offset groups, respectively. 85 and 84% of eyes had a postoperative astigmatism of 0.5 D or lower in the symmetric and asymmetric offset groups, respectively. Conclusion We have not found a significant difference in the refractive outcomes between the symmetric group and the asymmetric group of eyes treated both with TransPRK for preoperatively hyperopic or mixed astigmatism.

AIM: To compare the subjective and objective visual quality between small incision lenticule extraction (SMILE) and transepithelial photorefractive keratectomy (tPRK) in patients with low and moderate myopia. METHODS: Patients undertaking SMILE or tPRK for the correction of low and moderate myopia were consecutively recruited in this prospective cohort study with a 3-month follow-up period. Objective evaluation [visual acuity test, manifest refraction, wavefront aberrations, the total cut-off value of the total modulation transfer function (MTFcut-off), and Strehl ratio (SR)] and subjective evaluation of visual quality (quality-of-life questionnaire) were conducted before surgery and at days 1, 7, 30, and 90 after surgery. RESULTS: A total of 47 patients (94 eyes) with SMILE and 22 patients (22 eyes) with tPRK were enrolled. The uncorrected visual acuity (UCVA) was better in SMILE patients on day 7 after surgery (1.13±0.13 vs 0.99±0.17, t=4.85, P

AIM: To compare intraocular pressure (IOP) measured via the trans palpebral IOP (tpIOP) method using a Diaton or with a Goldman applanation tonometer (GAT) and study the determinants of IOP difference in eyes undergoing transepithelial photorefractive keratectomy (TPRK) for myopia. METHODS: This cross-sectional validation study was held in 2020 in an eye hospital in Saudi Arabia. IOP was measured by Diaton and GAT before treatment, after one week, and one month of TPRK. It is considered if IOP difference by Diaton and GAT was less than ±2 mm Hg acceptable. The IOP difference was tested if correlated to spherical equivalent (SE), central corneal thickness (CCT), age, gender, or tpIOP. RESULTS: Totolly 200 myopic eyes of 100 patients were included in the study. The mean difference of IOP measured by two methods before TPRK, 1wk, and 1mo after TPRK were 0.790, -0.790, and -0.920 mm Hg, respectively (P

Purpose: To compare the differences in the removal of bandage contact lenses (BCLs) at 4 and 7 days after transepithelial photorefractive keratectomy (TransPRK) in term of visual rehabilitation, eye discomfort, and postoperative complications. Methods: This retrospective cohort study included patients with myopia undergoing TransPRK; in Group 1, the BCLs were removed on the 4th postoperative day, while in Group 2, the BCLs were removed on the 7th postoperative day. All patients underwent a 6-month follow-up, including slit-lamp examination and visual acuity assessment. Subjective evaluations of pain and eye discomfort were recorded after the BCLs removal. Results: In total, 376 eyes of 191 patients in Group 1 and 346 eyes of 177 patients in Group 2 were enrolled. The two groups were matched for sex, age, preoperative corrected distance visual acuity, and tear film break-up time. Patients in Group 1 exhibited slightly lower levels of myopia, resulting in a shallower ablation depth and shorter ablation time than those in Group 2. No statistically significant differences in visual acuity recovery, haze severity, and incidence of infectious keratitis were observed within 6 months after surgery between the two groups. However, patients in Group 2 experienced significantly fewer discomfort symptoms (discharge, foreign body sensation, and blurred vision) after BCLs removal than patients in Group 1 and had fewer postoperative complications (recurrent corneal epithelial erosion). Conclusion: Delayed removal of the BCLs one week after TransPRK effectively alleviated early discomfort symptoms and reduced the risk of recurrent corneal epithelial erosion without increasing the likelihood of infectious keratitis.

PURPOSE: To present changes in transpalpebral intraocular pressure (tpIOP) in eyes after transepithelial photorefractive keratectomy (TPRK) in myopic Saudi patients and its determinants. METHODS: This one-armed cohort included the myopic eyes of Saudi adolescents treated with TPRK in 2020–2021. The difference in tpIOP before surgery, 1 week after surgery, and 1 month after surgery using Diaton was the main outcome. Central corneal thickness (CCT), myopia grade, gender, age, and corneal epithelial thickness before surgery were independent factors. Matched-pair analysis was conducted. The determinants of tpIOP post-TPRK were studied. RESULTS: Our cohort included 193 eyes of 97 participants (25.6 ± 5.8 years). Mild, moderate, and severe myopia were present in 93, 79, and 21 eyes, respectively. tpIOP was 22 mmHg or more in 5 and 8 eyes at 1-week and 1-month follow-up, respectively. The change in tpIOP ranged from − 7.00 to + 11.0 mmHg at 1 week and − 8.0 to + 26.0 mmHg at 1 month. The median change of CCT at 1 month was 59 μ. Change in tpIOP was not correlated with change in CCT at 1 month (r = −0.107, Pearson P = 0.14). Change of tpIOP was significantly correlated to spherical equivalent (SE) before surgery (matched-pair P < 0.001). SE (Mann–Whitney U P = 0.02) and tpIOP (Mann–Whitney U P = 0.02) before TPRK were significantly correlated to tpIOP >22 mmHg after TPRK. CONCLUSION: The changes in tpIOP following refractive surgery correlate to the refractive status of the eye and tpIOP before surgery.

Background: In eyes with hyperopia, astigmatism, and mixed astigmatism Transepithelial photorefractive keratectomy (TransPRK) is a modality of surface ablation surgery. We center on the corneal vertex for all our treatments (all have an offset to the center of the pupil) and wanted to compare the visual results of symmetrical profile treatments versus asymmetrical profile treatments (the center of the treatment on the vertex and the boundaries with the pupil center) using TransPRK as corneal refractive surgery. Methods: We retrospectively analyzed two consecutive groups of eyes treated with TransPRK in the Aurelios Augenlaserzentrum Recklinghausen: 47 eyes treated with symmetrical offset and 51 eyes treated with asymmetrical offset. The intergroup comparisons were assessed using unpaired Student's T-tests, whereas preoperative to postoperative changes were assessed using paired Student's T-tests. Results: Refractive outcomes were good for both groups. 83 and 88% of eyes were within the spherical equivalent of 0.5 D from the target in the symmetric and asymmetric offset groups, respectively. 85 and 84% of eyes had a postoperative astigmatism of 0.5 D or lower in the symmetric and asymmetric offset groups, respectively. Conclusion: We have not found a significant difference in the refractive outcomes between the symmetric group and the asymmetric group of eyes treated both with TransPRK for preoperatively hyperopic or mixed astigmatism. [ABSTRACT FROM AUTHOR]

PURPOSE: To present changes in transpalpebral Intraocular pressure (tplOP) in eyes after transepithelial photorefractive keratectomy (TPRK) in myopic Saudi patients and its determinants. METHODS: This one-armed cohort included the myopic eyes of Saudi adolescents treated with TPRK in 2020-2021. The difference in tplOP before surgery, 1 week after surgery, and 1 month after surgery using Diaton was the main outcome. Central corneal thickness (CCT), myopia grade, gender, age, and corneal epithelial thickness before surgery were independent factors. Matched-pair analysis was conducted. The determinants of tplOP post-TPRK were studied. RESULTS: Our cohort included 193 eyes of 97 participants (25.6 ± 5.8 years). Mild, moderate, and severe myopia were present in 93, 79, and 21 eyes, respectively. tplOP was 22 mmHg or more in 5 and 8 eyes at 1-week and 1-month follow-up, respectively. The change in tplOP ranged from - 7.00 to + 11.0 mmHg at 1 week and - 8.0 to + 26.0 mmHg at 1 month. The median change of CCT at 1 month was 59 jx. Change in tplOP was not correlated with change in CCT at 1 month (r= -0.107, Pearson P= 0.14). Change of tplOP was significantly correlated to spherical equivalent (SE) before surgery (matched-pair P < 0.001). SE (Mann-Whitney U P = 0.02) and tplOP (Mann-Whitney U P = 0.02) before TPRK were significantly correlated to tplOP >22 mmHg after TPRK. CONCLUSION: The changes in tplOP following refractive surgery correlate to the refractive status of the eye and tplOP before surgery. [ABSTRACT FROM AUTHOR]

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Abstract 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).

AIM: To compare the efficacy between two different silicone hydrogel bandage contact lenses after transepithelial photorefractive keratectomy (T-PRK). METHODS: In this randomized controlled trial, a total of 89 patients (178 eyes) who underwent T-PRK at the Qingdao Eye Hospital from October to December 2019 were selected. One random eye wore a Senofilcon A bandage contact lens after surgery, and the other eye a Balafilcon A bandage contact lens. Pain scores, uncorrected visual acuity (UCVA), spherical equivalent (SE), corneal epithelial healing status, epithelial thickness, bandage lenses deposits, lenses movement, and ocular surface conditions were measured and compared. RESULTS: There were no differences between the two groups in UCVA, SE, corneal epithelial healing status, corneal epithelial thickness, tear river heights and tear film rupture time at each follow-up visit. However, postoperative pain scores in the Senofilcon A group were significantly lower than those of the Balafilcon A group (Fintergroups=67.833, P

Abstract 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 0.05). 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.

Aim The aim of this study was to compare mechanical photorefractive keratectomy (PRK) to transepithelial photorefractive keratectomy (tPRK), used to correct mild and moderate myopia, with respect to the epithelial thickness mapping (ETM). Setting The study was carried out at Al-Mashreq Eye Center, Cairo, Egypt. Patients and methods This is a prospective comparative study that was carried out on 20 myopic patients (40 eyes), with spherical equivalent (SE) ranging from −1.0 to −5.0 D. The cases were divided into two groups: group A included the right eyes (OD) of all patients, and group B included the left eyes (OS). Group A underwent mechanical PRK using ‘hockey stick’ and excimer laser, using Mel-90 excimer laser with 250 Hz mode, and 0.7-mm spot scanning. Group B underwent tPRK using Mel-90 (8-mm lamellar ablation for 55 μm, 250 Hz). Uncorrected visual acuity (UCVA), manifest refraction, and ETM using AngioVue spectral domain optical coherence tomography systems were performed. The ETM was measured preoperatively and at 1 week, 1 month, and 3 months postoperatively. In addition, postoperative pain was assessed. Results The median preoperative UCVA was 0.3 (range, 0.2–0.4) in both eyes (OU), whereas the median preoperative best-corrected visual acuity was 1 (range, 0.8–1). There was a statistically significant increase in UCVA across the postoperative period in both groups (P

Transepithelial photorefractive keratectomy (TransPRK) is an established surface ablation technique used to correct refractive errors. Using anterior segment optical coherence (AS-OCT), it is now possible to measure the epithelium thickness and input these data into the laser platform. In this study, we explore whether better results were obtained in this way. To this end, we retrospectively analyze the results from a low-myopia group treated with a customized epithelium thickness, as measured using AS-OCT, and compare them with the results from a group treated with an optimized standard epithelium thickness. The customized epithelium profile group contains more eyes with vision better than 20/20, and more eyes in this group gain one line of corrected distance visual acuity (CDVA). In conclusion, with the customized epithelium thickness, we obtain superior results using TransPRK in low-myopia corrections.

Aim: To report the five-year results of Trans-epithelial Photorefractive Keratectomy (TPRK) in treating all kinds of refractive errors. Methods: In this retrospective cohort study, we quantitatively compared the clinical findings and assessment of optical and refractive parameters, including slit-lamp, corneal topography, Best Corrected Visual Acuity (BCVA), and Uncorrected Distance Visual Acuity (UDVA) in 172 eyes of myopic, hyperopic, and astigmatic patients before and five years after trans-PRK. Results: The average time for post-surgery epithelial healing was 2.97 0.83 days in male and 2.94 0.87 days in female patients; pain score in a week following the operation was 1.88 0.68 in males and 2.25 0.73 in females. Corneal haze was observed in five patients. No long-term adverse effect was reported. The pre-operative UDVA was 0.84 0.32 in male and 0.87 0.34 in female patients; while the post-operative UDVA was -0.02 0.04 in male and -0.01 0.02 in female patients. There was a highly significant correlation (P-value

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. [ABSTRACT FROM AUTHOR]

We aimed to report the five-year results of Trans-epithelial Photorefractive Keratectomy (TPRK) in treating all kinds of refractive errors. In this retrospective cohort study, we quantitatively compared the clinical findings and assessment of optical and refractive parameters, including slit-lamp, corneal topography, Best Corrected Visual Acuity (BCVA), and Uncorrected Distance Visual Acuity (UDVA) in 172 eyes of myopic, hyperopic, and astigmatic patients before and five years after trans-PRK. The average time for post-surgery epithelial healing was 2.97±0.83 days in male and 2.94±0.87 days in female patients; the pain score in a week following the operation was 1.88±0.68 in males and 2.25±0.73 in females. Corneal haze was observed in five patients. No long-term adverse effect was reported. The pre-operative UDVA was 0.84±0.32 in male and 0.87±0.34 in female patients; while the postoperative UDVA was -0.02±0.04 in male and - 0.01±0.02 in female patients. There was a highly significant correlation (P<0.001) in all indices except UDVA, which was almost near to being significant (P=0.07). In this survey, the mean safety and index were nearly 1.00. TPRK is a safe and efficient therapeutic procedure to treat all types of refractive errors, including myopia, hyperopia, and astigmatism, with no significant adverse effect. Being touchless and having a short recovery time are two main characteristics of this refractive surgery. [ABSTRACT FROM AUTHOR]

Chulaluck Tangmonkongvoragul,1,2 Sumet Supalaset,3 Napaporn Tananuvat,1,2 Somsanguan Ausayakhun1,2 1Department of Ophthalmology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand; 2CMU LASIK Center, Center of Medical Excellence, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand; 3Department of Ophthalmology, Chulabhorn Hospital, HRH Princess Chulabhorn College of Medical Science, Chulabhorn Royal Academy, Bangkok, ThailandCorrespondence: Chulaluck TangmonkongvoragulDepartment of Ophthalmology, Faculty of Medicine, Chiang Mai University, 110 Inthawarorot Road, Sri Phum, Muang, Chiang Mai, 50200, ThailandTel +66 53-935512Fax +66 53-936121Email chulaluck.t@cmu.ac.thPurpose: 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.Keywords: transepithelial photorefractive keratectomy, TransPRK, adolescent, two-step PRK, EX500

AIM: To investigate demographic and preoperative factors increasing the risk of ametropia following transepithelial photorefractive keratectomy (transPRK) in myopia and myopic astigmatism. METHODS: This retrospective cohort study included myopic eyes (-0.50 to -8.75 D) with or without astigmatism (up to 3.50 D) enrolled at Dr. Yap Eye Hospital Yogyakarta. TransPRK was performed using Technolaz 217z100 excimer laser. Subjects were clustered into ametropia and emmetropia group based on uncorrected distance visual acuities (UDVA) 3mo post-operatively. Multiple preoperative and intraoperative parameters were analyzed using Logistic regression to obtain their effect on ametropia risk following transPRK. RESULTS: A total of 140 eyes of 87 consecutive subjects were studied. Prevalence of ametropia following transPRK was 20 (14.29%) eyes. Subjects in ametropia group were significantly older than the emmetropia group (31.80±14.23 vs 18.88±2.41, respectively; P-6 D; OR=12.78), steeper anterior keratometric readings (Kmax>45 D and mean K>44 D; OR=4.28 and 4.35, respectively) increased the risk of ametropia following transPRK. Adjusted multivariate Logistic regression analysis showed that age was the strongest predictor for the incidence of ametropia following transPRK. Complications of transPRK were overcorrection, suspected posterior keratoectasia and accommodation insuffiency. CONCLUSION: Older age can be the strongest factor for increasing ametropia risk following transPRK. Cut-off points of Kmax and mean K at 45 and 44 D respectively are proposed as the predictors for ametropia following transPRK.

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). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

PURPOSE: Keratoconus (KC) leads to gradual progressive loss of vision in young and adult patients. For the purpose of visual rehabilitation and for hindering KC progression in patients, we designed this study. The main aim of this study is to help the KC patients to improve and stabilize their vision. METHODS: This prospective consecutive uncontrolled study includes 36 eyes of 36 patients with moderate degree of KC. All patients underwent combined wavefront-guided transepithelial photorefractive keratectomy (TPRK) and accelerated corneal collagen cross-linking (ACXL) after intracorneal ring segment (ICRS) implantation. Different measures will be evaluated at baseline, after ICRS implantation, and at one, 3, 6, and 12 months after combined (TPRK and ACXL). These measurements are uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE), corneal indices based on Scheimpflug tomography, and higher-order aberrations (HOAs) based on (Sirius, Schwind) tomography. RESULTS: There were significant improvements in logMAR (UDVA and CDVA) and reduction in sphere, manifest cylinder, MRSE, maximal keratometry, and mean keratometry after ICRS implantation in the first stage. After TPRK and ACXL as the second stage, there were significant improvements in visual acuity of both logMAR UDVA and CDVA. Reduction in refractive outcomes, including MRSE, sphere, and manifest cylinder. All corneal indices including steep, flat, mean, and maximal keratometries had been decreased. Furthermore, there were significant improvements in the final root mean square, HOAs, and coma aberrations from baseline. CONCLUSION: In moderate KC, triple therapy of ICRS implantation followed by combined TPRK and ACXL appears to be a safe and effective approach. This approach provides an improvement in visual acuity, refraction, corneal indices, and HOAs. These improvements were maintained for 1 year postoperatively. It also halts KC progression. [ABSTRACT FROM AUTHOR]

Purpose: To comprehensively compare visual quality between small incision lenticule extraction (SMILE) and transepithelial photorefractive keratectomy (tPRK). Methods: Sixty‐four eyes in the SMILE group and 42 eyes in the tPRK group were enrolled in this study. In both groups, visual acuity, manifest refraction, higher‐order aberrations (HOAs), contrast sensitivity (CS) at four spatial frequencies (3, 6, 12, 18 c/d) under three conditions (photopic, low glare, high glare), the cut‐off value of the modulation transfer function (MTFcut‐off), the objective scatter index (OSI) and the Strehl ratio (SR) were measured preoperatively and 1, 3 and 6 months postoperatively. Results: At 6 months postoperatively, the SMILE and tPRK groups showed similar safety, efficacy and predictability. Additionally, MTFcut‐off, SR and OSI exhibited comparable results. In contrast, the photopic area under the logarithm of the CS function (AULCSF) showed better outcomes in the tPRK group than in the SMILE group (SMILE versus tPRK: 1.21 ± 0.10 versus 1.25 ± 0.09, p = 0.014). Furthermore, the induced coma aberrations were larger in the SMILE group (SMILE versus tPRK: 0.10 ± 0.16 versus 0.06 ± 0.12, 95% CI [0.08, 0.31], p < 0.0001). Conclusions: Both SMILE and tPRK obtained comparable visual quality at 6 months postoperatively, accompanied by better photopic CS and smaller induced coma aberrations with tPRK. Paying more attention to alignment or developing a centration technique would be beneficial for visual quality when performing SMILE. [ABSTRACT FROM AUTHOR]

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.

AIM: To observe the effect of transepithelial photorefractive ketatectomy(TPRK)on corneal curvature, asphericity and aberrations. METHODS: Twenty-nine patients(58 eyes)were enrolled. The 1mm-8mm zone curvature, target curvature and 3mm ring curvature, corneal asphericity(Q value)and corneal aberration was measured and analyzed before and 6mo after TPRK surgery. RESULTS: In the 1mm-8mm zone, the corneal curvature all had significant decrease after TPRK surgery. The curvature 3mm ring after operation was 39.20±1.99D, and the curvature target was 39.51±1.99D. And both values had a significant correlation(r=0.98). The Q values before and after operation were -0.44 to -0.30, 0.34-0.66 respectively (PP>0.05).CONCLUSION: After TPRK operation, corneal curvature decreased significantly, and the change in zone of 3mm was the largest. The Q value, total high-order aberration, spherical aberration and vertical coma increased significantly after TPRK operation.

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)

Abstract 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.

Purpose: To evaluate the outcomes of wavefront-optimized (WFO) and topography-guided (TG) transepithelial photorefractive keratectomy (transPRK) in the treatment of myopia and myopic astigmatism., Methods: Patients who underwent transPRK using the WaveLight EX500 excimer laser for the correction of myopia and myopic astigmatism between January 2022 and March 2023 were divided into groups of WFO transPRK (77 eyes of 36 patients) or TG transPRK (63 eyes of 31 patients) in this retrospective, observational cohort study. The preoperative and postoperative 3-month refractive and visual outcomes of the two groups were analyzed., Results: In both groups, the uncorrected distance visual acuity was 0.0 logarithm of the minimum angle of resolution or better in 95% of eyes 3 months postoperatively, and the mean manifest refraction spherical equivalent was within ±1.0 diopter in 90% of eyes. No significant differences were observed between the groups in terms of the uncorrected distance visual acuity or astigmatism. A significant induction of higher order aberrations (HOAs) was observed in both groups. However, the induction of total corneal HOAs (p = 0.014) and spherical aberrations (p &lt; 0.001) was significantly lower in the TG group than that in the WFO group., Conclusions: WFO and TG transPRK effectively improved the visual and refractive outcomes; however, the induction of total corneal HOAs and spherical aberration was lesser following the TG ablation.

Purpose: The aim of this study was to correlate ablation depth on corneal endothelial cell (EC) indices following transepithelial photorefractive keratectomy (TPRK) in Saudi myopic patients., Methods: This was a retrospective cohort study of myopic eyes treated with TPRK. The changes in EC density and other indices were noted one week (W1) and 12 weeks (W12) after TPRK, which was the primary outcome. The laser ablation depth (AD) was correlated to the EC indices. The preoperative factors were also correlated to the outcomes using regression analysis to review predictors of change in the EC density., Results: We had 120 eyes of 60 myopic patients operated on for TPRK. The mean of maximum AD (Adm) and central AD (ADc) were 110.3±23.7 µ and 108.8±24.4 µ, respectively. The median change in EC count at W1 and W12 were -9.5 (interquartile range (IQR) -33.0, 17.0) and -3.0 (IQR -29.3, 13.3), respectively. The ADm was negatively correlated to a change in EC density at W1 (Wilcoxon (Z) =-2.7, P = 0.006) and at W12 (Z = -3.74, P <0.001). ADm (Kruskal-Wallis (K-W) test (P) = 0.167), ADc (K-W P = 0.08), central corneal thickness (K-W P = 0.65), and use of mitomycin-C (K-W P = 0.357) were not significant predictors of the change in EC density at W1. None of the variables significantly influenced the change in EC density at W12., Conclusions: The corneal ablation depth for TPRK is correlated to changes in EC density at W1 and W12 after TPRK., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Alrashidi et al.)

AIM: To evaluate the early postoperative efficacy of SMART for myopia and compare it with TransPRK.METHODS: Retrospective non-randomized controlled study. Totally 120 eyes of 60 patients with myopia who underwent SMART and TransPRK in our hospital from January to August 2018 were selected respectively. The uncorrected visual acuity(UCVA), visual quality, pain score, corneal epithelial healing and subepithelial haze were compared between two groups.RESULTS: There was no statistical differences between two groups regarding the proportion of UCVA reaching or exceeding 1.0 at 5d, 1mo and 3mo after operation(P>0.05), but the visual quality of SMART group was better than that of TransPRK group at 5d after operation(Pvs 3.07±1.07; 1.22±0.61 vs 0.84±0.59)on the 1st day and 3rd day after operation(Pvs 83.3%, Pst and 3 mo after operation, there was no difference in haze between the two groups(5.0% vs 5.0% and 8.3% vs 10.0%; P>0.05).CONCLUSION: There is no significant difference between SMART and TransPRK in the speed and stability of visual acuity recovery, but the early postoperative pain of SMART is lighter, the corneal epithelium is healed faster, and the visual quality is better.

Aim: To study the effect of mitomycin C (MMC) applied during transepithelial photorefractive keratectomy (TPRK) on the corneal endothelium one week (W1) and three months (M3) after surgery and its determinants., Methods: In this two-armed cohort study conducted in 2022, eyes treated with MMC during TPRK (group 1) were compared with eyes not treated with MMC (group 2). The corneal endothelial cell (EC) count, EC density (ECD; cells/mm 2 ), average (µm 2 ), standard deviation (µm 2 ), coefficient of variation (CV%), EC max , EC min , and EC percentage of hexagonality were estimated at W1 and M3. The postoperative changes in the EC count in the two groups were compared and correlated with the other independent variables., Results: Group 1 had 26 eyes, and group 2 had 78 eyes. All TPRK indices were significantly higher for the eyes in group 1 than for those in group 2. The MMC usage was not a significant predictor of the change in ECD ( P =0.644), change in CV ( P =0.374), and change in the percentage of hexagonality of EC ( P =0.164) at W1. However, the use of MMC was a significant predictor of changes in CV ( P =0.014) and the change in the percentage of hexagonality of EC ( P =0.039) at M3. The duration of laser exposure and the size of the optical zone influenced the correlation of MMC use with the changes in EC indices, postoperatively., Conclusion: The use of MMC doesn't affect ECD, CV, and percentage of hexagonality at W1 if other surgical indices are considered. At M3 after operating myopic eyes by TPRK, MMC significantly influence the CV and percentage of hexagonality. The duration of the laser application and the size of the optical zone should be considered when determining the effect of MMC on the EC indices., Competing Interests: Conflicts of Interest: Alrashidi SH, None., (International Journal of Ophthalmology Press.)

Purpose: The aim of this study was to evaluate visual quality after high-frequency transepithelial photorefractive keratectomy (t-PRK) by assessing the relationship between the operational parameters and the first-year postoperative corneal higher-order aberrations (HOAs).Methods: This was a retrospective study of low-to-moderate myopic eyes treated with t-PRK. The files of 46 low-to-moderate myopic patients (90 eyes; myopia up to -5D) were included in the study. Eyes having a cylindrical refractive error more than 2D and the patients not having completed a 1-year follow-up were excluded from the study. Factors including age, preoperative mean spherical equivalent (MSE), mean keratometry (Km), central corneal thickness (CCT), scotopic pupil, optical zone (OZ), transition zone (TZ), ablation zone (AZ), central ablation depth (CAD), and static cyclotorsion correction (SCC) were analyzed for association with the first-year postoperative corneal HOAs.Results: Corneal HOAs were found to be increased postoperatively with a 6-mm pupil (P < 0.05). The increased spherical aberration had a positive correlation with patient age, preoperative MSE, Km, TZ, and CAD, whereas it had a negative relationship with OZ and AZ (P < 0.05). The corneal coma had a significantly positive correlation with preoperative MSE and a significantly negative relationship with OZ (P < .05).Conclusion: Postoperatively induced corneal HOAs may affect patients' scotopic vision (night time driving, cinema) when the pupils get larger. The relationship between patient age, preoperative MSE, Km, CAD, TZ, OZ, AZ, and postoperative corneal HOAs underlines the need to consider the effects of these parameters on the final vision quality. [ABSTRACT FROM AUTHOR]

AIM:To compare dry eye symptoms and signs before and after three kinds surgery, femtosecond laser-assisted laser in situ keratomileusis(FS-LASIK), transepithelial photorefractive keratectomy(T-PRK), small incision lenticule extraction(SMILE)using ocular surface analyzer(Oculus Keratograph). METHODS:Totally 98 patients(196 eyes)undergoing corneal refractive surgery from January 2017 to May 2017 were recruited. They were divided into three groups, namely, FS-LASIK group, T-PRK group and SMILE group. All patients underwent observation and assessment in the following order: ocular surface disease index(OSDI), tear meniscus height(TMH), measure using the infrared pattern of Oculus Keratograph. The first tear film break-up time(FBUT)and average tear break-up time(ABUT)measure using the infrared pattern of Oculus Keratograph, corneal fluorescein staining(FL), Schirmer Ⅰ test(SⅠt). RESULTS:1)OSDI index: There was statistically significant difference between the three groups(Fgroups=2.799, PgroupsFtime=85.942, PtimeP=0.019), and the OSDI values of the T-PRK group were higher than those of the other two groups. 2)TMH: There was statistically significant difference among the three groups postoperatively(Fgroups=1.720, PgroupsFtime=11.202, PtimeP=0.004), and the inferior TMH in the SMILE group was higher than that of the other two groups. 3)FBUT: There was statistically significant difference among the three groups after surgery(Fgroups=1.428, Pgroups=0.245). The difference in FBUT values between different time points in each group was statistically significant(Ftime=4.511, Ptime=0.001). The FBUT values of each group were significantly reduced after 1wk and 1mo, and recovered to preoperative levels after 3mo and 6mo. There was no significant difference in FBUT between different groups at each time points(P>0.05). 4)ABUT: There was statistically significant difference in ABUT among the three groups after surgery(Fgroups=1.290, PgroupsFtime=10.294, PtimeP=0.008); among them, the ABUT value of the SMILE group was higher than that of the T-PRK group and the FS-LASIK group. 5)FL: There was no statistical difference in the FL score between the three groups(Fgroups=0.816, Pgroups=0.445). The differences in the FL scores at different points in each group were statistically significant(Ftime=5.539, Ptime=0.004). The FL score of each group was significantly higher than before surgery at 1wk and 1mo, and recovered to preoperative levels at 3mo and 6mo after surgery. There was no statistical difference in the FLs between different groups at different points in time(P>0.05). 6)SⅠt: There was no statistically significant difference in SⅠt values among the three groups after surgery(Fgroups=0.225, Pgroups=0.799). The difference in SⅠt values between different time points in each group was statistically significant(Ftime=4.604, Ptime=0.003). The SⅠt values of each group were slightly higher than the preoperative values afyer 1wk and 3mo, but they were all within normal values. There was no significant difference between the SⅠt values of 1mo or 6mo after operation and the preoperative level. There was no statistical difference in SⅠt values between different groups at each points in time(P>0.05).CONCLUSION:The three types of corneal refractive surgery FS-LASIK, T-PRK, and SMILE all cause different degrees of dry eyes within a certain period of time after surgery, but they can gradually recover later. After SMILE surgery, the stability of the tear film recovered faster, while the symptoms after T-PRK surgery improved the least.

Abstract 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.

Abstract 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.

Abstract 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

AIM: To observe the early clinical effects of smart pulse technology(SPT)-assisted transepithelial photorefractive keratectomy(TPRK).METHODS: This was a retrospective non-randomized research. There were 260 patients(508 eyes)who were underwent SPT-assisted TPRK surgery. The best corrected visual acuity(BCVA)was recorded at 1 to 2wk before surgery. The uncorrected visual acuity(UCVA)was recorded at 1mo and 3mo after surgery. Corneal epithelial growth status and haze grade were recorded after surgery. Record the degree of pain within 3d after surgery and satisfaction surveys in all patients.RESULTS: After 1mo and 3mo, UCVA(-0.080±0.0798, -0.108±0.089)achieved or even better than preoperative BCVA(-0.050±0.0561). Corneal epithelial wounds were completely repaired in all patients during 5d after operation. In the follow-up of 1mo and 3mo after operation, the corneas of most patients are clear except for 3 cases who had haze in 0-1 grade. Very satisfied patients accounted for 93.0%.CONCLUSION: SPT-TPRK surgery is safe. The average postoperative UCVA can reach or even exceed the preoperative average BCVA.