The microstructure of cornea verticillata in Fabry disease and amiodarone-induced keratopathy: a confocal laser-scanning microscopy study

Abstract

The purpose of this study is to describe cornea verticillata in Fabry disease and in amiodarone-induced keratopathy and to compare the corneal microstructure of both types. Ten eyes from ten normal subjects, 28 eyes from 22 patients with Fabry disease confirmed by molecular genetic studies, and 16 eyes from 11 patients receiving amiodarone were examined by slit-lamp microscopy and in-vivo confocal laser-scanning microscopy (CLSM) with following three-dimensional reconstruction of the individual corneal layers. Five patients with Fabry disease were monitored during the course of enzyme replacement therapy (ERT). Evidence of cornea verticillata was found by slit-lamp microscopy both in patients with Fabry disease and in those with amiodarone-induced keratopathy; CLSM revealed the same pattern of hyper-reflective deposits in the basal cell layer of corneal epithelium in both sets of patients. Microdot changes in the anterior stroma were more prevalent in patients receiving amiodarone but do not presuppose the simultaneous presence of cornea verticillata. The bulbar conjunctiva was found to be normal in all patients. The tarsal conjunctival epithelium contained round hyper-reflective structures, which are also encountered physiologically, but these were more common in patients with Fabry disease. In one out of the five patients examined, monitoring of corneal changes over time during ERT disclosed a regressive tendency of the deposits in the epithelial basal cell layer documented by CLSM. The microstructural corneal changes typically seen in cornea verticillata in both Fabry disease and in amiodarone-induced keratopathy can be successfully visualized by confocal in-vivo microscopy at the level of the basal cell layer. By analogy, with the grading system for cornea verticillata based on slit-lamp microscopy, staging of these deposits in the basal cell layer can also be performed following in-vivo CLSM. The microdots in the anterior stroma as well as the changes observed in the tarsal conjunctiva should be regarded as having less diagnostic value because such changes may also occur in normal subjects. The utility of CLSM as a tool for monitoring ERT in Fabry disease over time needs to be confirmed in studies with larger sample sizes conducted over a longer period.