A New Mixture Of Vital Dyes For Ocular Surface Staining

Abstract

Abstract: : Purpose:Sodium fluorescein (FL) is universally considered the premier vital dye for corneal staining, and similarly, rose bengal (RB) the premier vital dye for conjunctival staining. Norn reported the use of a mixture of 1% FL and 1% RB as advantageous in daily practice. Norn (1973) introduced lissamine green (LG) as an ocular stain and suggested that it was identical in function to RB. Mixtures of LG with other vital ocular stains have not been reported. The purposes of this study were to: review the clinical staining characteristics of the three dyes (FL, RB and LG) when applied in controlled dose and concentration; evaluate the stinging characteristic of the three dyes; determine whether optimal staining of the cornea and bulbar conjunctiva can be accomplished by applying a mixture of the dyes; and determine the specific concentrations of the dyes required for optimal staining of the cornea and bulbar conjunctiva free of ocular discomfort. Methods:Sixteen solutions of FL, RB, and LG and their mixtures were evaluated. An inclusion criterion for entrance was grade 1 to 2 of corneal staining when stained with 10 µl of 2% FL, and grade 1 to 2 of conjunctival staining when stained with 10 µl of 1% RB. Subjects were then studied with various mixtures of the vital dyes. A standard volume of 10 µl of each mixture was instilled into the conjunctival sac after gentle depression of the lower eyelid. Examination of FL staining was made using 16x magnification, a cobalt blue filter, and a slit lamp beam approximately 5 mm in width and 10 mm in height. Examination of LG and RB staining was made similarly but with white light. Results:A mixture of 2% FL and 1% RB was the most efficacious mixture for staining of both cornea and conjunctiva; however, moderate to marked discomfort was frequently encountered. The mixture of 2% FL and 1% LG did not result in ocular discomfort, and provided excellent staining of both the cornea and conjunctiva. Concentrations of 2% and 3% LG produced stinging and burning discomfort. The fluorescent characteristics of FL were not significantly altered by the addition of 1% LG. A mixture of 2% FL and 1% LG was the preferred mixture for simultaneous and efficacious staining of the cornea and the conjunctiva without ocular discomfort. Conclusions:A mixture of 2% FL and 1% LG offers excellent simultaneous staining of the cornea and bulbar conjunctiva, and could replace the use of individual dyes for studying ocular staining in both pathology of the ocular surface and in contact lens practice.

Keywords: cornea: tears/tear film/dry eye • conjunctiva