Management of Anterior Stromal Necrosis After Polymethylmethacrylate ICRS: Explantation Versus Exchange With Corneal Allogenic Intrastromal Ring Segments

Abstract

PURPOSE: To evaluate management of keratoconic eyes with anterior stromal necrosis overlying the intracorneal ring segment (ICRS), by either ICRS explantation alone or exchange with corneal allogenic intrastromal ring segments (CAIRS). METHODS: Among 643 Intacs SK (Additional Technology, Inc) inserted at one institutional center, 16 eyes (15 patients) with overlying spontaneous anterior stromal necrosis were identified. Data included size of stromal defect and refractive and topographical findings before ICRS insertion, before anterior stromal necrosis, and 6 months after intervention. RESULTS: The 10-year incidence of anterior stromal necrosis after femtosecond laser–assisted ICRS insertion was 5.5%. Eight eyes underwent ICRS removal only and 8 eyes had ICRS exchanged with CAIRS. In the first group, CDVA worsened from 0.14 before melt to 0.28 logMAR after removal ( P = .10), simulated keratometry (SimK) and maximum axial keratometry (Kmax) increased from 44.73 to 46.34 diopters (D) ( P = .14) and from 49.23 to 52.26 D ( P = .14), respectively, and coma worsened from 0.87 to 1.52 D ( P = .02). In the CAIRS group, CDVA of 0.16 before melt improved to 0.11 logMAR postoperatively ( P > .99), and topographic indices stabilized with SimK, Kmax, and coma mildly altering from 45.31 to 45.44 D ( P > .99), from 49.25 to 49.64 D ( P > .99) and from 0.87 to 0.81 D ( P > .99), respectively. Whether the ICRS were explanted or exchanged, the visual and topographic mean values were better than those reported before ICRS implantation, whereas higher order aberrations in eyes without CAIRS regressed to levels before ICRS insertion. At the site of melt, thinnest residual stromal thickness averaged 327 µm with ICRS removal and 490 µm with CAIRS. Eyes with larger melt areas resulted in less optimal results with CAIRS implantation. CONCLUSIONS: Early experience in the management of anterior stromal necrosis by exchange of polymethylmethacrylate ICRS with CAIRS seems to avoid stromal thinning and confer better visual and topographic results, which were more pronounced with thicker segments. The benefit of CAIRS in large stromal melts needs to be investigated. [ J Refract Surg . 2022;38(4):256–263.]