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Objectives To assess and compare the six-month outcome of the two-step transepithelial phototherapeutic keratectomy- photorefractive keratectomy (PTK-PRK) and the single-step transepithelial PRK for myopia and myopic astigmatism. Methods A prospective randomized study. The study enrolled 100 eyes of 50 patients with mild to moderate myopia or myopic astigmatism stratified into two groups, PTK-PRK ( n = 50 eyes) and single step PRK ( n  = 50 eyes). Primary outcome measures were visual acuity and manifest refraction. Secondary outcome measures were epithelial healing duration, post-PRK pain scores and 3-month postoperative haze grading. Results Preoperative characteristics were similar in both groups ( p value > 0.05). The mean uncorrected distance visual acuity (UDVA) at 1 week, 1 month, 3 and 6 months was significantly better in the single-step PRK group than in the two-step PTK-PRK group ( p  < 0.001). The mean manifest sphere, cylinder and spherical equivalent showed a significant difference at all follow up visits in favour of the single-step PRK ( p value < 0.001). Epithelial healing duration was faster in single-step PRK ( p value < 0.001). Pain scores were significantly lower following single-step PRK at 8 h, 1 day, 3 days ( p value < 0.001) but were similar at the 7th day. Haze scores showed no statistical difference between the two groups at 3-month follow-up. Conclusion The two transepithelial PRK techniques were effective in correcting mild to moderate myopia and myopic astigmatism. However, Single-step transepithelial PRK achieved faster visual recovery, better refractive outcome and shorter epithelial healing time with less post-PRK pain. Clinical trials registry (Clinical Trials.gov Identifier): NCT04710082.

To compare differences in clinical outcomes of symmetric offset (SO) and asymmetric offset (AO) centration strategies in photorefractive keratectomy (PRK) in patients with myopia and/or astigmatism,  forty refractive surgery candidates who visited Farabi Eye Hospital’s refractive surgery clinic from May to August 2022 were enrolled in the study. We randomly assigned one of each patient’s eyes to the AO and the other one to the SO group using random blocks. Patients were followed for four months (median of 114 days). Ablation profile, Visual acuity (VA), and higher order aberrations (HOAs) were evaluated. Effective optical zone (EOZ) and its circularity index were calculated automatically by a MATLAB-based algorithm. There was no significant difference between the two groups’ total ablation volume and maximum and central ablation depth (all P > 0.05). The two groups showed significant differences in minimum ablation depth, with a higher value for SO than AO (0.03 ± 0.03 and 0.01 ± 0.01, respectively, P-value < 0.001). 95% and 93% of the eyes in the AO and SO groups achieved UDVA of 20/20 or better at four months postoperatively (P-value = 0.78, Chi-square). There were no significant differences between postoperative mean RMS of higher order aberrations (HOAs) among AO and SO groups (all P > 0.05). The EOZ was 6.05 ± 0.64 in the SO group and 6.05 ± 0.68 in the AO group (P value = 0.99, paired t-test). 95% and 93% of the eyes in the AO and SO groups achieved UDVA of 20/20 or better at four months postoperatively (P-value = 0.78, Chi-square). Symmetric and asymmetric offset centration strategies result in safe and effective refractive correction. The refractive and visual outcomes of both methods were similar in low and moderate myopic astigmatism patients.

Background Transepithelial photorefractive keratectomy (Trans-PRK) is an effective and safe laser surgery for myopia. Following this procedure, a bandage contact lens is used to promote epithelial healing, reduce postoperative pain, and improve visual recovery. The base curve of these lenses may affect vision post-surgery, particularly in patients with steep corneas and high myopia. This study aims to investigate the impact of using bandage contact lenses with base curves of 8.4 mm versus 8.8 mm on visual recovery after Trans-PRK in patients with steep corneas and high myopia. Methods This is a randomized, double-blind, binocularly controlled, single-center trial. The study subjects are myopic patients scheduled for Trans-PRK. Both eyes in each patient will be treated consecutively with single-step Trans-PRK. After surgery, a contact lens with an 8.8-mm base curve will be placed on one eye, and a lens with an 8.4-mm base curve will be placed on the other. The primary objective is to determine the difference in early postoperative uncorrected visual acuity between the two eyes of patients with steep corneas and high myopia. Randomization will be conducted using a computer-generated random allocation sequence without blocks or restrictions. The sequence will be recorded in sealed opaque envelopes, maintained by the principal investigator until the trial’s conclusion. In this double-masked trial, subjects will not know which treatment each eye receives. Discussion This novel trial will provide information on how bandage contact lenses with different base curves promote epithelial healing and visual recovery after Trans-PRK, thus offering evidence for clinical practice. Trial registration ClinicalTrials.gov NCT06393855. Registered on May 1, 2024. https://clinicaltrials.gov/study/NCT06393855 .

Purpose To compare clinical outcomes of transepithelial photorefractive keratectomy (t-PRK) and conventional epithelium-off PRK (PRK) in patients with high compound myopic astigmatism. Methods Sixty eyes of 30 myopic individuals with at least −2.50 diopters (D) of spherical equivalent and 3.00 D of cylindrical refractive error were enrolled in the study. Both eyes of each patient were randomly assigned to either the t-PRK method or epithelium-off PRK as a matched contralateral control group. Refractive outcomes were evaluated 6 months after surgery. Results At the 6-month visit, cylindrical refractive error magnitude was lower in the t-PRK (0.51 ± 0.29 D) compared to the PRK (0.67 ± 0.30 D) group (P = .04). The residual astigmatism was 0.50 diopters or less in 23 eyes (76%) in the t-PRK group and 15 eyes (50%) in the PRK group. In vector analysis using the Alpins method, t-PRK resulted in a significantly higher percentage of success of astigmatic surgery (84.68 ± 8.95 in t-PRK versus 79.46 ± 10.88 in PRK, P = .04). Additionally, there was a marginal advantage for the t-PRK group regarding index of success of astigmatism surgery (P = .06) and absolute (P = .08) and arithmetic (P = .07) angles of error compared to the PRK group. Both groups had an equal safety profile. Conclusions T-PRK is more accurate for astigmatic correction in high astigmatism than conventional PRK. Both t-PRK and PRK are comparable respecting safety and efficacy. [J Refract Surg. 2024;40(12):e956–e965.]

Purpose: To compare clinical outcomes and patient satisfaction of photorefractive keratectomy (PRK) and small incision lenticule extraction (SMILE) for myopia. Methods: This contralateral, randomized, prospective clinical trial included 86 eyes of 43 patients diagnosed as having spherical equivalent (SE) from −1.00 to −8.00 diopters (D). One eye of each patient was randomly allocated to receive either PRK with 0.02% mitomycin C or SMILE. Visual acuity measurement, slit-lamp microscopy, manifest and cycloplegic refraction, Scheimpflug corneal tomography, contrast sensitivity assessment, ocular wavefront aberrometry, and a satisfaction questionnaire were performed preoperatively and during an 18-month follow-up. Results: Forty-three eyes of each group completed the study. After 18 months of follow-up, eyes treated with PRK and SMILE showed comparable results regarding uncorrected distance visual acuity (−0.12 ± 0.07 and −0.25 ± 0.09, respectively), safety, efficacy, contrast sensitivity, and ocular wavefront aberrometry. For predictability, eyes treated with PRK had a statistically lower residual spherical equivalent when compared with eyes treated with SMILE. Residual astigmatism of 0.50 D or less was achieved in 95% of the PRK group and 81% of the SMILE group. At the 1-month follow-up visit, the PRK group presented worse evaluation in relation to vision and foreign body sensation when compared to the SMILE group. Conclusions: Both PRK and SMILE presented as safe and effective strategies for treating myopia with comparative clinical results. Eyes treated with PRK showed lower spherical equivalent and residual astigmatism. In the first month, eyes treated with SMILE showed less foreign body sensation and faster visual recovery. [J Refract Surg. 2023;39(3):180–186.]

To compare visual outcomes and postoperative aberrations after surface ablation performed with a 750-Hz versus a 1,050-Hz excimer laser coupled with an ablation software designed to reduce corneal surface irregularity. Retrospective comparative trial of myopic eyes that had refractive surgery consecutively treated with transepithelial advanced surface ablation with a 750-Hz excimer laser (750 group) versus a 1,050-Hz excimer laser coupled with the Smart Pulse Technology ablation software (SPT group). The SPT algorithm is a laser pulse technology software aimed at reducing surface irregularity of the stromal bed at the end of treatment. The authors evaluated the effect of this smoothing on final visual acuity. Patients were observed for 6 months. A total of 139 eyes in the 750 group and 40 eyes in the SPT group were evaluated. Epidemiological and preoperative refractive data of the two groups were comparable. Uncorrected distance visual acuity improved with time and was significantly better in the SPT group (-0.04 ± 0.61 logMAR for the SPT group vs 0.02 ± 0.78 logMAR for the 750 group) (P < .001). At 6 months, 55% versus 21% achieved 20/16 or better (P = .005) and 90% versus 65% achieved 20/20 or better (P = .019) visual acuity in the SPT and 750 groups, respectively. Corrected distance visual acuity improved with time and appeared to be influenced by group (P = .054), with better results in the SPT group. Coma and trefoil improved significantly with time in a similar manner in both groups. Surface ablation with the 1,050-Hz excimer laser and SPT software, aimed at reducing the final superficial stromal irregularity, led to improvement of 6-month uncorrected visual acuity. [J Refract Surg. 2017;33(2):89-95.].

Background To compare the clinical outcomes of transepithelial photorefractive keratectomy (TPRK) with femtosecond laser-assisted in situ keratomileusis (FS-LASIK) for correction of high myopia. Methods In this prospective, non-randomised, cohort study, 85 eyes of 46 patients treated with TPRK and 80 eyes of 42 patients treated with FS-LASIK were included. All eyes were highly myopic (spherical equivalent refraction <− 6.00 diopters). Both TPRK and FS-LASIK were performed by Schwind Amaris 750S excimer laser. Visual acuity, refraction, corneal high order aberration (HOA) and other variables were analyzed before and at 1, 3, 6, 12 months after surgery. Results At 12 months after surgery, uncorrected logMAR distance visual acuity (UDVA) in the TPRK and FS-LASIK groups was − 0.04 ± 0.04 and − 0.01 ± 0.08, respectively ( P  = 0.039). Corrected logMAR distance visual acuity (CDVA) was − 0.06 ± 0.05 and − 0.04 ± 0.05 in both groups ( P  = 0.621). For UDVA, 86% of eyes in the TPRK group and 80% in the FS-LASIK group remained unchanged or improved one or more logMAR lines ( P  = 0.314), compared to preoperative CDVA. For CDVA, 97% of eyes in the TPRK group and 90% in the FS-LASIK group remained unchanged or improved one or more lines ( P  = 0.096), compared to preoperative CDVA. Spherical equivalent refraction was − 0.05 ± 0.39 and − 0.26 ± 0.47 in both groups ( P  = 0.030). 87% of eyes in the TPRK group and 73% in the FS-LASIK group achieved ±0.50 D target refraction ( P  = 0.019). All 85 eyes (100%) in the TPRK group and 75 eyes (92%) in the FS-LASIK group were within ±1.00 D of target ( P  = 0.003). Root mean square (RMS) of corneal total HOA and vertical coma in the TPRK group were lower compared with the FS-LASIK group ( P  < 0.001 for both variables). Conclusions TPRK and FS-LASIK showed good safety, efficacy and predictability for correction of high myopia. Clinical outcomes of TPRK were slightly better than FS-LASIK.

Purpose: This study aimed to evaluate the corneal epithelial thickness changes after photorefractive keratectomy (PRK) and the impact of long-term artificial tear usage on epithelial thickness changes in these patients. Methods: This study was performed on 71 patients (142 eyes) without dry eye disease who received PRK for myopic refractive correction. The corneal epithelial thickness profile was obtained before, one, three, and six months after surgery using anterior segment optical coherence tomography. Patients were randomly divided into two groups: group A, who received preservative-free artificial tears post-surgery, and group B, who did not receive artificial tears. Results: The epithelial thickness decreased universally in the first month and then increased in the 3- and 6-month follow-ups. Group A had a significantly thicker epithelium in central, paracentral, and midperipheral zones compared with group B in the 3-month follow-up. In the 6-month follow-up, no significant differences were detected between groups. At the last follow-up, the central, paracentral, and midperipheral zone epithelial thicknesses in all patients were significantly higher than preoperative values, but peripheral zone thickness only increased to preoperative values. Conclusions: Patients using artificial tears showed a faster thickening, especially in the central and paracentral zones, but there were no significant differences between the two groups in the final follow-up. Artificial tear usage may increase the rate of the epithelial remodeling process in post-PRK patients without significantly altering the final epithelial thickness profile. Further studies are warranted to evaluate the influence of different factors on epithelial remodeling.

Purpose. To assess the effect of platelet-rich plasma (PRP) on the healing response of the corneal epithelium in eyes undergoing phototherapeutic keratectomy (PTK). Methods. We prospectively examined 20 eyes of 10 patients undergoing bilateral PTK for granular corneal dystrophy or band keratopathy. Patients were randomly assigned to start topical administration of PRP ophthalmic suspension (PRP group) or artificial tears (control group) 4 times daily for 2 weeks. Immediately, 1, and 2 days, and 1 week after PTK, we quantitatively measured the staining area of the corneal epithelium, using slit-lamp photography. We also determined the subjective symptoms and the satisfaction, using the visual analogue system (VAS). Results. The staining area in the PRP group was significantly smaller than that in the control group on days 1 and 2 (Wilcoxon signed-rank test, p=0.022 and p=0.017, respectively), but not on day 7 (p=0.317). The recovery rate of the corneal epithelium in the PRP group was significantly higher than that in the control group on days 1 and 2 (p=0.022 and p=0.017, respectively), but not on day 7 (p=0.317). We found no significant differences in pain (p=0.139), foreign body sensation (p=0.108), epiphora (p=1.000), or satisfaction (p=0.295), between the two groups. Postoperative complications did not occur in any of the eyes in the study. Conclusions. The PRP treatment was effective for enhancing corneal epithelial recovery in the early postoperative period, without significant adverse events, in post-PTK-treated eyes, suggesting that it may hold promise as one of the treatment options for treating such postsurgical patients.

PURPOSE: To compare the influence of femtosecond lenticule extraction (FLEx) and small incision lenticule extraction (SMILE) on corneal nerve density and the ocular surface for equivalent degrees of correction of myopia. METHODS: Sixty eyes of 30 patients (8 males and 22 females, mean age: 31.0 ± 6.0 years) were included in the study. The patients underwent FLEx in 1 eye and SMILE in the other eye by random assignment. Subbasal nerve density was measured using confocal microscopy preoperatively and at 1 week, 1 and 3 months, and 1 year postoperatively. Ocular surface parameters such as Schirmer’s test results, tear film break-up time, and corneal sensation were performed preoperatively and at 1 and 3 months postoperatively. RESULTS: In the FLEx group, subbasal nerve density was 18,390 ± 6,090 In the FLEx group, subbasal nerve density was 18,390 ± 6,090 µ m/mm 2 preoperatively and 5,770 ± 3,490 µ m/mm 2 at 1 year postoperatively ( P < .001, Dunnett’s test). In the SMILE group, subbasal nerve density was 16,810 ± 6,220 µ m/mm 2 preoperatively and 11,870 ± 8,200 µ m/mm 2 at 1 year postoperatively ( P = .21). The decrease in corneal nerve density was significantly less after SMILE than after FLEx at all postoperative visits (Mann–Whitney U test, P < .05). FLEx resulted in a significant decrease in Schirmer’s test results, tear film break-up time, and corneal sensation at all postoperative visits, whereas SMILE induced no significant changes in these parameters ( P > .05). CONCLUSIONS: There was less damage to the sub-basal nerve plexus of the cornea and less effect on the ocular surface parameters after SMILE than after FLEx. [[ J Refract Surg . 2015;31(1):10–15.]