Confocal laser-scanning microscopy allows differentiation between Fabry disease and amiodarone-induced keratopathy

Background The aim of this work is to compare the microstructure of cornea verticillata in Fabry disease with amiodarone-induced keratopathy by means of in vivo confocal laser-scanning microscopy (CLSM). Methods Ten eyes of ten patients suffering from Fabry disease, six eyes of six patients with amiodarone-induced keratopathy and eight eyes of healthy control subjects were examined by conventional slit-lamp microscopy and CLSM. One Fabry patient received amiodarone therapy. All Fabry patients were under enzyme replacement therapy with agalsidase alfa. Results Seven out of ten Fabry patients and all patients receiving amiodarone showed typical cornea verticillata on slit-lamp examination. CLSM revealed hyper-reflective intracellular inclusions in basal epithelial cells of all Fabry patients with cornea verticillata and in one Fabry patient without slit-lamp-detectable vortex keratopathy, as well as in all eyes featuring amiodarone keratopathy. Amiodarone deposits were more reflective and of grossly different size. Seven Fabry patients and all amiodarone patients had stromal microdots. Two amiodarone patients showed amiodarone inclusions in the endothelium. The number of CLSM changes in Fabry patients did not correlate with that of slit-lamp detectable cornea verticillata. Conclusions While Fabry-induced cornea verticillata and amiodarone keratopathy cannot be distinguished by conventional slit-lamp microscopy, CLSM allows the differentiation between both etiologies in the majority of patients. CLSMappears to reveal corneal changes prior to the detection of cornea verticillata on slit-lamp microscopy and may thus be helpful in the early diagnosis of Fabry disease. CLSM does not allow quantitative monitoring of corneal changes in Fabry patients under enzyme-replacement therapy.