The interaction between hydrogel lenses and sodium fluorescein. Theoretical and practical considerations

The interaction between sodium fluorescein dye and hydrophilic contact lenses was assessed quantitatively by spectrophotometry. Absorption of dye into he lens matrix was found to be proportional to the exposure time and also depends on the optical power and water content of the lens. 0.9% saline appeared preferable to oxidising agents as a rinsing solution in decontamination procedures. 3% hydrogen peroxide solution affects the nature of fluorescein such that it becomes colourless and also absorb less incident light, whilst still being retained within the lens. The implications of our findings for practical lens decontamination and theoretical fluorescein/polymer binder are discussed.