Faculty Bibliography

PURPOSE/OBJECTIVE:The purpose of this study was to report a serious complication of early sterile keratolysis associated with a presbyopia inlay implantation combined with hyperopic laser in situ keratomileusis (LASIK). METHODS:A 55-year-old hyperopic man underwent uneventful topography-guided bilateral femtosecond laser-assisted hyperopic LASIK, combined with same-day polymer refractive inlay implantation in the nondominant eye for additional presbyopia correction. Within 2 months, anterior sterile keratolysis and partial extrusion required surgical explantation of the inlay, and long-term medical management over 9 years achieved effective visual rehabilitation documented also with corneal imaging. RESULTS:Immediate postoperative results were binocular 20/20 uncorrected distance visual acuity and J1 uncorrected near visual acuity. The early progressive anterior sterile keratolysis and partial extrusion necessitated surgical explantation at 2 months, severe anterior scarring of the perforated flap area and severe focal flattening of the cornea of over 10 diopters, developed despite aggressive topical corticosteroid use. The uncorrected distance visual acuity in the OS dropped from 20/25 to 20/400. The LASIK flap portion that underwent keratolysis and perforated, remodeled long-term from a scarred, epithelial plug with early significant surface concavity to evidently a mild subepithelial localized hazy area with regularized curvature over a period of 9 years. CONCLUSIONS:Some refractive synthetic corneal inlays have been recalled because they may result in significant corneal haze. We present herein a case of severe keratolysis that necessitated surgical explantation and further document long-term care for eventual visual rehabilitation.

PUPOSE/UNASSIGNED:To describe the concordance of keratoconus expression in two pairs of monozygotic twins before and after a combined CXL/PRK procedure. SETTING/METHODS:Private Ambulatory Eye Surgery Unit. DESIGN/METHODS:Retrospective Interventional Twin Study. METHODS:Two pairs of male monozygotic twins with keratoconus (KCN) were studied retrospectively. Improvement of flattest (k1) and steepest (k2) keratometry, Index of Height Decentration (IHD), corneal thickness at thinnest point and corneal epithelial thickness measured by AS-OCT and Scheimpflug tomography was compared between respective eyes of monozygotic twin siblings 1 to 5 years after the application of combined corneal cross linking (CXL) and topography guided photorefractive keratectomy (PRK) of part of the refractive error (the Athens Protocol). RESULTS:Significant improvement was noted in all the keratometric indices of all 8 eyes after the combined CXL/PRK procedure.The difference in k1, k2, IHD corneal thickness at thinnest point and corneal epithelial thickness percentage improvement between the right eyes of each pair of twins was statistically significant 1 and 5 years post-operatively (P < .05). Statistically significant discordance in the aforementioned parameters percentage improvement was likewise observed between the left eyes of each pair of twins (P < .05). CONCLUSIONS:Although a genetic predisposition in KCN is well documented, the discordance in keratometric indices improvement after a CXL/PRK procedure between respective eyes of monozygotic twins suggests that environmental influences may contribute to the disease expression as well. Variable degree of synergy in a combined CXL/PRK procedure may also explain the aforementioned discordant improvement.

PURPOSE/OBJECTIVE:To define and compare the centration of the ablation effect in LASIK to the corresponding effect in SMILE, in myopic laser vision correction in order to possibly explain the refractive performance differences noted between the two procedures in a contralateral eye study. SETTING/METHODS:Private Ambulatory Eye Surgery Unit. DESIGN/METHODS:Prospective randomized contralateral eye study. METHODS:In 22 consecutive patients (44 eyes), one eye was prospectively randomized to have myopic topography-guided LASIK treatment and the contralateral eye to have SMILE; Digital image analysis of the achieved centration to the aimed corneal vertex was assessed for both procedures on the perioperative Scheimpflug tangential curvature maps, using a proprietary digitized methodology. RESULTS:The radial displacement between the attempted centration on the corneal vertex versus the center of the effective anterior corneal curvature flattening was on average 130 ± 62 μm in the LASIK group and 313 ± 144μm in the SMILE group (P<0.001). CONCLUSIONS:In this contralateral eye study, topography-guided myopic LASIK was found to achieve significantly better effective centration compared to myopic SMILE, in regards digitally measured decentration of the effective refractive change achieved in the anterior corneal curvature from the corneal vertex. This may explain the previously reported superior visual outcomes in the LASIK group eyes when compared to the contralateral SMILE group eyes.

PURPOSE/OBJECTIVE:The aim of this study was to report novel ray-tracing customization of surface excimer laser ablation combined with higher fluence corneal crosslinking (CXL) in the stabilization and normalization of ectasia and visual rehabilitation of progressive keratoconus. METHODS:A 28-year-old man with bilateral progressive keratoconus was treated with Athens protocol: CXL combined with photorefractive surface ablation customized by a novel artificial intelligence platform calculating lower- and higher-order aberrations based on wavefront, Scheimpflug tomography, and interferometry axial length data from a single diagnostic device. Visual acuity, refractive error, keratometry, optical coherence tomography and Scheimpflug tomography, and endothelial cell density were evaluated over 12 months. RESULTS:Keratoconus stabilized in both eyes. Uncorrected distance visual acuity changed from 20/80 to 20/20 in the OD and from 20/40 to 20/25 in the OS at 12 months. Keratometry changes were as follows: from 40.7 and 42.7 at 165.1 degrees to 41.4 and 43.1 at 169.3 degrees in the OD and from 40.9 and 42.6 at 15.9 degrees to 44.1 and 44.7 at 9.8 degrees in the OS. Corneal surface normalization was as follows: index of height decentration from 0.115 to 0.099 and index of surface variance from 77 to 67 in the OD and index of height decentration from 0.066 to 0.014 and index of surface variance from 49 to 31 in the OS. CONCLUSIONS:We introduced in this study the management of progressive keratoconus with CXL combined with novel excimer laser customization using several independent up-to-now diagnostics calculated by software, evaluating bidirectional theoretical ray tracing. It bears the potential advantage of addressing more accurately normalization of the distorted human eye optics associated with corneal ectasia, compared with using anterior corneal surface data or wavefront data alone.

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.].