[On the etiology of dystrophia corneae verticillata]

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

PURPOSE

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.

PATIENTS AND METHODS

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).

RESULTS

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.

CONCLUSIONS

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.

Fabry's disease and cornea verticillata. A report of 3 cases

Fabry's disease is a rare familial disorder of glycolipid metabolism which is caused by a deficiency of a lysosomal enzyme alpha-galactosidase. A Finnish family is described in which cornea verticillata was found in the father and 2 daughters. In all cases, there were symptoms suggesting Fabry's disease: febrile episodes the origin of which was not clear, limb pains and, in the case of the father, 20 years of proteinuria with elevated ESR, and hemiplegia and aphasia following a cerebral thrombosis at the age of 43. The diagnosis was confirmed by demonstration of an alpha-galactosidase deficit in the serum and urine of all patients. Deficiency of this enzyme leads to abnormally high urinary tri- and dihexosyl ceramide levels, and this was observed in the father and the elder daughter. At the age of 12, the daughter had loss of vision in her right eye as a result of occlusion of the central retinal artery. Electron microscopic (EM) examination of the father's dermal angioma suggested Fabry's disease. Computerized cranial tomography of the father revealed not only the cerebrovascular condition but also a disease affecting the white matter of the brain.