Toxic effect of rose bengal dye on the living human corneal epithelium.

Abstract

To investigate whether rose bengal dye at a concentration of 1% has a toxic in vivo effect on the human corneal epithelium. 80 patients with presumed keratoconjunctivitis sicca (KCS) were examined with break-up time, Schirmer 1 test, and staining with fluorescein sodium and rose bengal. The corneal surface was observed in the slit lamp and photographed by means of non-contact photomicrography. After the application of rose bengal 1% in eyes preinstilled with fluorescein sodium 1% myriads of green dots appeared on the corneal surface in all 32 patients with KCS according to Copenhagen criteria, in 17/18 with low Schirmer 1 test values only, and in 21 of the remaining 30 in whom the KCS diagnosis wasn't verified. The appearance of green microdots after the application of rose bengal was probably due to the interruption of intercellular junctions and the penetration of fluorescein stained fluid below the superficial cells. Whether this phenomenon reveals an unhealthy corneal surface and thus has a clinical significance has to be further investigated.