Visibility and Depth of the Stromal Demarcation Line After Corneal Collagen Cross-Linking Using Anterior Segment Optical Coherence Tomography: Comparison Between Isoosmolar and Hypoosmolar Riboflavin.

Abstract

To evaluate and compare visibility and depth of the stromal demarcation line (DL) created after corneal collagen cross-linking (CXL) using anterior segment optical coherence tomography (AS-OCT) between 2 groups: CXL with isoosmolar and hypoosmolar riboflavin. In this retrospective study performed at Metz-Thionville Regional Hospital, consecutive patients with progressive keratoconus underwent CXL using an accelerated protocol (10 min, 9 mW/cm ultraviolet-A). AS-OCT (RS-3000, Nidek) was performed at 1 month after surgery, with stromal DL visibility graded. The corneal demarcation line depth (DLD) was also measured. Seventy-five eyes of 58 patients with a mean age of 25.2 ± 9.1 years were enrolled in the study. Preoperative mean anterior Kmax was 57.4 ± 5.4 D. The mean thinnest pachymetry was 474.3 ± 35.7 μm. The mean depth of the stromal DL on 1-month optical coherence tomography evaluation was 331.2 ± 62.7 μm. A DL was visible (grades 1 and 2) in 54 (72%) treated eyes. A positive correlation was found between patient age and the DLD: deeper lines were found in older patients [r = 0.38, P = 0.005, confidence interval 95% (0.12; 0.58)]. Forty-one patients were included in the isoosmolar group and 34 in the hypoosmolar group: neither visibility nor DLD was significantly different between groups. The mean depth was 334.5 ± 67.5 μm and 328.1 ± 59.0 μm in the isoosmolar and hypoosmolar groups, respectively (P = 0.82). A DL was visible (grades 1 and 2) in 26 eyes (63.4%) and 28 eyes (82.4%) in the isoosmolar and hypoosmolar groups, respectively (P = 0.12). The use of isoosmolar or hypoosmolar riboflavin does not significantly modify the depth or visibility of the stromal DL 1 month after accelerated CXL on AS-OCT evaluation.