Faculty Bibliography

PURPOSE/OBJECTIVE:To compare attempted versus achieved corneal stromal thickness reduction in a consecutive case series of patients undergoing laser in situ keratomileusis (LASIK) in one eye and small incision lenticule extraction (SMILE) in the other eye. METHODS:This prospective, randomized, contralateral eye study included 22 consecutive patients (44 eyes), one eye randomized to have myopic LASIK and the contralateral eye to have SMILE. Anterior segment optical coherence tomography was performed preoperatively and at 3 months postoperatively. For each of the treatment groups, the achieved maximum stromal thickness reduction was compared to the planned/attempted thickness. The deviation of planned versus achieved stromal thickness reduction was then compared between the two groups. RESULTS:< .001). CONCLUSIONS:.

PURPOSE/OBJECTIVE:To investigate possible refractive changes in pregnant women who have previously undergone myopic laser in situ keratomileusis (LASIK). METHODS:This prospective study included 64 pregnant women (128 eyes) who had previously undergone bilateral myopic LASIK. Uncorrected distance visual acuity (UDVA), spherical equivalent, corneal keratometry, topography and tomography, and epithelial mapping were evaluated before LASIK, 12 months after LASIK, during the third trimester of pregnancy, and 1 year postpartum. RESULTS:The average age at the time of recruitment was 32.5 ± 5 years (range: 24.5 to 39.5 years). The evaluation during pregnancy was at an average 55 months (range: 12 to 108 months) from the initial LASIK procedure. The preoperative mean refractive error was -6.72 ± 2.96 diopters (D) (range: -1.00 to -11.00 D). Comparing 12-month refractive data after the original LASIK procedure to the those within the third trimester of the subsequent pregnancy, the average UDVA was 20/18, the residual refractive error was -0.63 ± 1.00 to -0.51 ± 0.82 D, the steepest keratometry value was 40.85 ± 1.89 to 40.88 ± 2.84 D, and the central epithelial thickness was 56.4 ± 3.89 to 57.38 ± 5.04 µm, respectively. CONCLUSIONS:In this study, pregnancy did not affect the refractive stability of LASIK. Pregnancy-related changes in refractive error, corneal stability, and total corneal and epithelial thickness in women after LASIK were not found to be statistically significant. [J Refract Surg. 2022;36(2):118-122.].

Purpose/UNASSIGNED:To evaluate and compare the repeatability and agreement of Scheimpflug vs scanning-slit tomography of the cornea and the anterior chamber in terms of keratometric and tomographic indices in healthy eyes. Methods/UNASSIGNED:The 20 eyes of 10 healthy participants underwent 3 consecutive measurements using both Scheimpflug-tomography and scanning-slit tomography, diagnostic devices. Multiple corneal and anterior chamber tomographic parameters were recorded and evaluated to include corneal keratometry and its axis; corneal best-fit sphere (BFS), pachymetry mapping, angle kappa, anterior chamber depth (ACD), pupil diameter, and location. Repeatability for each device was assessed using the within each subject standard deviation of sequential exams, the coefficient variation (CV) and the intraclass correlation coefficient (ICC). Agreement between the two devices was assessed using Bland-Altman plots with 95% limits of agreement (LoA) and correlation coefficient (r). Results/UNASSIGNED:Both devices were found to have high repeatability (ICC>0.9) both in keratometric and other tomographic measurements. Scheimpflug tomography's repeatability though appeared superior in the average keratometry values, anterior and posterior BFS, thinnest corneal pachymetry value and location (p<0.05). Agreement: Statistically significant inter-device differences were noted in the mean values of K1, K2, BFS, ACD and thinnest corneal pachymetry (p<0.05). Despite the agreement differences noted, the two devices were well correlated (r>0.8) in respective measurements with Scheimpflug delivering consistently lower values than the scanning-slit tomography device. Conclusion/UNASSIGNED:Scheimpflug-tomography repeatability was found to be superior to that of scanning-slit tomography in this specific study, in most parameters evaluated. Inter-device agreement evaluation suggests that reading from the two devices may not be used interchangeably in absolute values, yet they are well correlated with Scheimpflug delivering consistently lower values in most.

Purpose/UNASSIGNED:Safety and efficacy of a novel automated ray tracing optimization in customization of excimer ablation in myopic LASIK. Methods/UNASSIGNED:In a consecutive case series, 25 patients (50 eyes) undergoing femtosecond-laser-assisted myopic LASIK were evaluated. The novel, artificial-intelligence platform initially calculates the ablation profile based on a model eye for each case, based on interferometry axial length data. Low- and high-order aberration calculation is performed by raytracing based on wavefront and Scheimpflug tomography measurements, all from a single diagnostic device. Visual acuity, refractive error, keratometry, topography, high-order aberrations and contrast sensitivity were evaluated, over six months follow-up. Results/UNASSIGNED:Change from pre- to 6 months post-operative: mean refractive error improved from -5.06 ± 2.54 diopters (D) (range -8.0 to -0.50 D) to -0.11 ± 0.09 D (range -0.25 to + 0.25); refractive astigmatism from -1.07 ± 0.91 D (range -4.25 to 0 D) to -0.15 ± 0.04 D (range -0.25 to 0); and topographic astigmatism from -1.65 ± 0.85 D to -0.26 ± 0.11 D (range -0.60 to 0). About 65% of eyes gained one line of vision and 38% 2 lines. Pre- to post-operative high-order aberration average: RMSh changed from 0.25 um to 0.35 um. Contrast sensitivity improved post-operatively. Conclusion/UNASSIGNED:We report safe and effective preliminary outcomes with a novel excimer laser customization by ray tracing optimization, for myopic LASIK treatments, employing several independent up-till-now diagnostics and a customized eye model reference for each case. It bears the potential advantage through total eye aberration data and ray tracing refraction calculation to offer improved and more predictable visual outcomes.

PURPOSE/OBJECTIVE:To report the safety and long-term efficacy of topography-guided partial-refraction PRK combined with corneal cross-linking (CXL) (the Athens Protocol), refractive, topographic, and pachymetric changes of keratoconic eyes treated were studied. METHODS:Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refraction, keratometry, qualitative and quantitative assessment of corneal keratometric, and pachymetric properties recorded by topography and tomography were evaluated for 10 years postoperatively. RESULTS:A total of 144 eyes were followed up for a mean 128 ± 4 months (range: 120 to 146 months). Mean UDVA markedly improved at 1 year (0.19 ± 0.17 to 0.53 ± 0.21 decimal) with further improvement to 0.55 ± 0.19 decimal at 10 years. CDVA increased from 0.59 ± 0.21 to 0.80 ± 0.17 decimal at 1 year and further to 0.81 ± 0.19 decimal at 10 years. Corneal thickness decreased from 468.74 ± 35.05 to 391.14 ± 40.07 μm at 1 year (P < .01) and up to 395.42 ± 32.21 μm at 10 years. Steep keratometry decreased from 50.57 ± 2.80 to 45.87 ± 2.70 diopters (D) (P < .01) at 1 year and to 44.00 ± 3.22 D at 10 years. Maximum keratometry decreased from 53.43 ± 2.97 to 46.17 ± 1.18 D at 1 year and 44.75 ± 2.14 D at 10 years (P < .01). A total of 94.4% demonstrated ectasia stabilization and 3.5% showed progressive "overcorrection" or "hyperopic" shift. CONCLUSIONS:The Athens Protocol confirms long-term safety and efficacy for corneal ectasia and visual function. Most parameters had little change after 1 year, through year 10. [J Refract Surg. 2019;35(8):478-483.].

PURPOSE/OBJECTIVE:To evaluate the safety, efficacy, and stability of topography-guided partial PRK combined with corneal cross-linking (CXL) (the Athens Protocol [AP]) in pediatric patients with keratoconus over a 4-year follow-up period. METHODS:This prospective study included 39 keratoconic eyes of 21 patients younger than 18 years with clinical and imaging evidence of keratoconus progression. Partial topography-guided excimer laser ablation in conjunction with high-fluence CXL was performed in all patients according to the AP. Uncorrected distance visual acuity, corrected distance visual acuity, refraction, keratometry, endothelial cell density, topography, and tomography using both Scheimpflug and optical coherence tomography (OCT) were evaluated for 4 years postoperatively. RESULTS:At 4 years postoperative, there was significant improvement in mean uncorrected distance visual acuity from 0.51 ± 0.31 (decimal) to 0.65 ± 0.26 (decimal; P < 0.05). Mean corrected distance visual acuity improved from 0.71 ± 0.22 (decimal) preoperatively to 0.81 ± 0.19 (decimal; P < 0.05), respectively. Mean flat keratometry (K1) and mean steep keratometry (K2) readings reduced from 44.95 ± 3.71 D and 49.32 ± 5.05 D, respectively, preoperatively to 43.14 ± 2.95 D and 46.28 ± 4.87 D, respectively, (P < 0.05) at 4 years. The mean anterior maximum keratometry (Kmax) reading reduced from 56.81 ± 2.94 D preoperatively to 48.11 ± 3.17 D at 48 months. The mean index of height decentration was 0.105 ± 0.054 μm preoperatively and 0.049 ± 0.024 (P < 0.05) at 4 years postoperative. Mean preoperative corneal thickness at the thinnest point was 436.7 ± 42.6 μm preoperatively, 392.50 ± 45.68 μm at 12 months postoperative, and 418.42 ± 17.01 μm at 4-year follow-up. Late-onset deep corneal haze, a potential intrinsic complication of this technique in pediatric patients, was encountered in 2 cases at least 1 year after the procedure. CONCLUSIONS:Long-term results of the AP seem to be safe and effective in pediatric patients, with marked improvement in visual function and keratometric symmetry indices.

PURPOSE/OBJECTIVE:To compare the outcomes and complications of Epi-Bowman blunt keratectomy (EBK) using a blunt epikeratome (Epi-Clear, Orca Surgical, Israel), with alcohol delamination of the corneal epithelium during photorefractive keratectomy (PRK) in contralateral eyes. METHODS:This prospective, randomized contralateral eye study included 44 eyes of 22 patients undergoing PRK for bilateral myopia or myopic astigmatism. In each patient, epithelial delimitation was performed using an Epi-Clear epikeratome EBK (EBK group) on 1 eye and diluted ethanol (EtOH) on the fellow eye (EtOH group). Postoperative pain, epithelial healing, epithelial profile, and visual outcome were compared between the 2 groups. RESULTS:The mean postoperative pain scores were 0.37 ± 0.25 for the EBK group and 0.82 ± 0.22 for the EtOH group (P = 0.043). The mean epithelial defect size at day 3 postoperatively was 1.61 ± 1.46 and 2.25 ± 1.69 mm, respectively (P = 0.034). The postoperative 3-month remaining mean spherical equivalent was 0.04 ± 0.49 diopters for the EBK group and 0.21 ± 0.26 D for the EtOH group (P = 0.520). There was no significant difference in UCVA and BCVA between the groups. CONCLUSIONS:Our data suggest that this novel EBK device and technique may minimize postoperative pain, accelerate re-epithelialization, and offer earlier visual recovery, compared with EtOH when used for myopic PRK.

PURPOSE/OBJECTIVE:To evaluate 3-dimensional epithelial remodeling in patients undergoing myopic laser in situ keratomileusis (LASIK) versus small incision lenticule extraction (SMILE). METHODS:In a prospective randomized contralateral eye study of LASIK versus SMILE procedures, 21 consecutive patients (42 eyes) were evaluated with corneal epithelial mapping by anterior segment optical coherence tomography for up to 2 years. RESULTS:In the LASIK group, central epithelial thickness increased from 52.38 ± 2.57 μm to 57.00 ± 4.23 μm and remained almost stable at this level for up to 24 months. In the SMILE eyes, it increased from 52.52 ± 3.01 μm to 57.15 ± 4.57 μm and also remained stable for up to 24 months. Both techniques created the same level of epithelial thickness increase and variation, with a significantly higher mid-peripheral epithelial thickness increase. The differences between the preoperative and postoperative changes were found statistically significant, but not different between the 2 techniques at any given time studied. CONCLUSIONS:Both LASIK and SMILE resulted in significant epithelial thickening. This response seemed to be surprisingly quite similar between the 2 different techniques. This study suggests that epithelial remodeling may correlate with relative curvature changes resulting after both techniques, rather than the obvious difference of subepithelial corneal denervation changes.

Purpose/UNASSIGNED:To evaluate the incidence of transient dry eye associated with LASIK for myopia and the efficacy of topical cyclosporine A administration. Methods/UNASSIGNED:Group A was formed from 145 (82 female, 63 male) eyes that developed clinically significant dry eye within 1 month post-LASIK and were subjected to cyclosporine A treatment. A "non-symptomatic for dry eye" and age- and gender-matched group (group B) was formed from the same pool of patients to serve as control. Schirmer's, tear film break-up time (TBUT) and Ocular Surface Disease Index (OSDI) questionnaire were evaluated. Central corneal epithelial thickness (CET) and topographic epithelial thickness variability (TVT) were evaluated as quantitative dry eye objective markers. Subjective patient survey was also assessed. Results/UNASSIGNED:<0.05), respectively. Following commencement of cyclosporine A treatment in group A, statistically significant improvement was noted, greater than the one in group B, in all metrics at the 12-month examination in comparison to the 1-month baseline. Conclusion/UNASSIGNED:Topical cyclosporine A treatment is an effective alternative in the management of LASIK for myopia-related transient dry eye. Optical coherence tomography epithelial mapping may provide an objective benchmark in diagnosing and monitoring this significant disorder and its correlation with visual symptoms.