Corneal flattening following collagen crosslinking for keratoconus: Findings at 5-year follow-up.

PURPOSE: To study the corneal flattening effect of cross-linking (CXL) overtime and to look for a potential association with preoperative topographic variables and the central depth of demarcation line (DDL). METHODS: 201 eyes of 146 patients (mean age of 31.2 ± 7.3 years) with progressive keratoconus who underwent CXL between June 2007 and December 2012 were enrolled in this retrospective study. Follow-up visits were performed at different time intervals for at least 5 years. Preoperative parameters and depth of demarcation line were collected from LaserVision ophthalmology center in Lebanon. Corneal flattening was defined by a change in postoperative Kmax (ΔKmax) greater than 1.00 D. RESULTS: ΔKmax increased from 50.25% to 61.69%, from first to last follow-up visits. The only factor significantly correlated to ΔKmax during all follow-up visits was preoperative maximum keratometry (Kmax) especially when greater than 50.00 D (OR, 1.92; 95% CI, 1.10-3.34). All eyes showed a corneal demarcation line (mean central depth (DDL): 217.11 ± 26.54 µm), with no statistically significant correlation between DDL and ΔKmax. CONCLUSION: CXL effect on cornea can be cumulative overtime and delayed flattening occurs in some cases. ΔKmax is positively correlated with preoperative Kmax and no association was found between ΔKmax and DDL. Therefore, DDL may not be a valid measure for the efficacy of CXL.

Corneal Stroma Cell Density Evolution in Keratoconus Corneas Following the Implantation of Adipose Mesenchymal Stem Cells and Corneal Laminas: An In Vivo Confocal Microscopy Study.

Purpose: To report the corneal stroma cell density evolution identified by in vivo corneal confocal microscopy in humans using injected autologous adipose-derived adult stem cells (ADASCs) and corneal decellularized laminas in corneas with advanced keratoconus. Methods: Interventional prospective, consecutive, randomized, comparative series of cases. A total of 14 keratoconic patients were randomly distributed into three groups for three types of surgical interventions: group 1 (G-1), autologous ADASC implantation (n = 5); group 2 (G-2), decellularized human corneal stroma (n = 5); and group 3 (G-3), autologous ADASCs + decellularized human corneal stroma (n = 4). Results: A gradual and significant increase (P < 0.001) was observed in the cellularity in the anterior and posterior stroma of patients in G-1, G-2, and G-3 a year after the surgery in comparison with the preoperative density level. The same result was observed at the mid-corneal stroma in G-1 and at the anterior and posterior surfaces and within the laminas in G-2 and G-3. The cell density of patients receiving ADASC recellularized laminas (G-3) was statistically significantly higher (P = 0.011) at the anterior surface and within the lamina (P = 0.029) and at the posterior surface than in those implanted only with decellularized laminas (G-2). Conclusions: A significant increase in cell density occurred up to 1 postoperative year at the corneal stroma following the implantation of ADASCs alone, as well as in those cases implanted with decellularized and recellularized laminas at the different levels of the analysis. However, this increase was significantly higher in the ADASC recellularized laminas.