Objective: To characterize morphologic changes in corneas of patients with recurrent erosion syndrome or epithelial basement membrane dystrophy using in vivo confocal microscopy.
Design: Observational case series
Participants: Fourteen eyes of eight patients with diagnosed epithelial basement membrane dystrophy and 13 eyes of seven patients with recurrent erosion syndrome were examined.
Methods: Slit-lamp examination and in vivo confocal microscopy. The pathologic findings are presented as digitized images obtained from video tape recorded during the confocal microscopy.
Main outcome measures: The morphology of corneal surface epithelial cells, basal epithelial cells, subbasal nerve plexus, Bowman's layer, stromal keratocytes, and endothelium was analyzed.
Results: The surface epithelium was intact in all but two eyes. One cornea (a basement membrane disorder with clinically visible dots) had multinucleate surface epithelial cells, and one eye with recurrent corneal erosions showed a freely floating surface epithelium sheet in the tear fluid. Patients in both groups showed islets of highly reflective cells with presumed intracellular deposits surrounded by normal cells in the basal epithelial cell layer. The basal epithelial cell area also showed other pathologic changes, including drop-shaped configurations, streaks, or ridges. Folding of the Bowman's layer was also observed in both groups. Anterior keratocytes showed signs of activation (highly reflective nuclei with visible processes) in some of the patients regardless of the clinical diagnosis, and in recurrent erosions even increased deposition of abnormal extracellular matrix in the anterior stroma was suspected. Posterior corneal keratocytes and endothelium appeared normal when examined. The subbasal nerve plexus showed various pathologic changes, such as short or strangely shaped nerve fiber bundles, decreased numbers of long nerve fiber bundles, only faintly visible long nerve fiber bundles (instead of the normally observed long parallel running interconnected bundles), or increased amounts of Langerhans cells, but only one patient (with recurrent erosion syndrome) lacked the subbasal nerve plexus.
Conclusions: In vivo confocal microscopy of corneas with recurrent erosions or epithelial basement membrane dystrophy showed deposits in basal epithelial cells, subbasal microfolds and streaks, damaged subbasal nerves, or altered morphology of the anterior stroma. Confocal microscopy cannot replace biomicroscopy in making a specific diagnosis, but it sometimes helps the diagnosis in corneas that appear normal under a biomicroscope.