Asymmetric Intrastromal Corneal Ring Segments with Progressive Base Width and Thickness for Keratoconus: Evaluation of Efficacy and Analysis of Epithelial Remodeling.

Purpose: The aim of this study is to describe visual outcomes and epithelial remodeling following the implantation of asymmetric intracorneal ring segments (ICRSs) of variable thickness and base width for the management of duck-type keratoconus. Methods: A prospective observational study of patients with duck-type keratoconus was conducted. All patients received one ICRS AJL PRO + implant (AJL Ophthalmic). We analyzed demographic and clinical data, anterior segment optical coherence tomography (AS-OCT) data and Scheimpflug camera images obtained with a Placido disc MS-39 (CSO, Firenze, Italy) one and six months after surgery to determine keratometric and aberrometric outcomes and epithelial remodeling. Results: We studied 33 keratoconic eyes. ICRS implantation significantly improved both corrected distance visual acuity (CDVA) and uncorrected distance visual acuity at six months, as assessed with the logMAR (minimum angle of resolution) system, from 0.32 ± 0.19 to 0.12 ± 0.12 (p < 0.001) and from 0.75 ± 0.38 to 0.37 ± 0.24 (p < 0.001), respectively. Overall, 87% of implanted eyes gained ≥ 1 line of CDVA, and 3% of patients (n = 1) lost one line of CDVA; 55% of eyes attained a manifest refraction spherical equivalent between +1.50 and -1.50 D. Epithelial remodeling was greater at the wider and thicker end (+11.33 µm ± 12.95; p < 0.001 relative to the initial value) than at the narrower and thinner end (+2.24 µm ± 5.67; p = 0.01). Coma aberration was significantly reduced from 1.62 ± 0.81 µm to 0.99 ± 0.59 µm (p < 0.001). Conclusions: AJL-PRO + ICRS implantation for duck-type keratoconus improves refractive, topographic, aberrometric and visual parameters and induces progressive epithelial thickening along the segment.

Comparative Study of Asymmetric Versus Non-asymmetric Intrastromal Corneal Ring Segments for the Management of Keratoconus.

PURPOSE: To compare the outcomes obtained with models of asymmetric and non-asymmetric intracorneal ring segments (ICRS) in keratoconic eyes with asymmetric topo-graphic patterns. METHODS: In this prospective observational study, ICRS were implanted alternately in patients with the same tomographic patterns of keratoconus assigned to four groups. Patients with the "duck" phenotype received one asymmetric or non-asymmetric ICRS and patients with the "snowman" pheno-type received two asymmetric or non-asymmetric ICRS. Visual, refractive, astigmatism, keratometric, and corneal aberrometry changes were evaluated over a 6-month follow-up period. RESULTS: Sixty-eight eyes were analyzed. No significant difference was observed between the use of one asymmetric and one non-asymmetric ICRS in duck phenotypes. In snowman keratoconus, the inferior-superior index decreased significantly (P = .03) with asymmetric but not with non-asymmetric ICRS implantation. Total corneal higher order aberrations and coma rates were lower, but not significantly so, after the implantation of two asymmetric ICRS in snowman phenotypes (2.85 ± 0.89 to 2.60 ± 0.91 µm, P = .20 and 2.64 ± 0.93 to 2.39 ± 0.98 µm, P = .21), and significantly higher after the implantation of two non-asymmetric ICRS (2.56 ± 1.28 to 3.08 ± 1.62 µm, P = .02 and 2.34 ± 1.27 to 2.84 ± 1.62 µm, P = .02). CONCLUSIONS: Asymmetric ICRS did not improve the outcomes of ICRS implantation in duck keratoconus. However, the implantation of two asymmetric ICRS was more effective than that of two non-asymmetric ICRS for decreasing vertical asymmetry and preventing increases in corneal aberration in the snowman phenotype of keratoconus. [J Refract Surg. 2021;37(8):552-561.].

Evaluation of the Spot Vision Screener for children with limited access to ocular health care.

PURPOSE: To compare the sensitivity, specificity, and referral rate of the Spot Vision Screener (Welch Allyn Inc, Skaneateles Falls, NY) with the gold standard cycloplegic measurements acquired using the Retinomax in a population of underprivileged children and teenagers with limited access to medical care. METHODS: Children were recruited for the study by social workers in the vicinity of Robert Debre Hospital, Paris, France. Refractive errors (hyperopia of ≥ +2.00 D spherical equivalent [SE]; myopia of ≤ -0.50 D SE; astigmatism of ≥1.00 D between the two main meridians; anisometropia of ≥1.00 D SE difference between eyes) were assessed using the Spot Vision Screener and the Retinomax. Sensitivity (true positive rate), specificity (true negative rate), and referral rate of this Spot Vision screening program were evaluated. RESULTS: A total of 82 eyes of 41 subjects (19 males) were included; mean age was 126 months of age (range, 48-246). The sensitivity of the Spot Vision Screener for the detection of refractive errors was 82.35%; specificity was 91.67%. The sensitivity of the Spot Vision Screener to detect hyperopia, myopia, astigmatism, and anisometropia was 27.27%, 84.61%, 78.57%, and 66.67%, respectively. Its specificity to detect hyperopia, myopia, astigmatism, and anisometropia was 100%, 98.55%, 89.71% and 94.29%, respectively. CONCLUSIONS: The specificity of the Spot Vision Screener to detect refractive errors was found to be relatively high (>90%). However, its low sensitivity for hyperopia seems to remain a major limitation of the device, because hyperopia is particularly important to detect in children given its high prevalence and possible adverse consequences. Global programs using cycloplegic measurements should be considered an alternative.