Free radical production in patients undergoing long-term topical antiglaucoma treatment or contact lens wearers by impression cytology specimens

Purpose: To investigate free radical production in impression cytology specimens using microplate cold light cytofluorimetry. Methods: 60 impression cytology specimens (IC) were harvested in 30 patients aged from 20 to 90 years. IC were taken in 10 healthy subjects, 10 glaucoma patients receiving longterm treatment for glaucoma and 10 contact lens wearers for more than five years. A complete ophthalmologic examination (BUT, corneal staining) was performed. Evaluation of free radical production was done using a dichlorofluoresceine diacetate (DCFH-DA) test for H(2)O(2) evaluation and a hydroethidine test for O(2)(-) measurement. Results: The BUT values in the two pathological groups were significantly lower than those of controls (p<0.001). A free radical production was found in both contact lens wearers (p<0.001 compared to control values) and glaucoma patients (p<0.001 compared to control values). Both hydrogen peroxyde and superoxide anion productions were significantly correlated to the decrease of BUT values and the increase of superficial punctuate keratitis. Conclusion: The results of this preliminary study confirm that conjunctival epithelial cells may abnormally produce oxygen free radicals in chronic ocular surface disorders. This may participate to the cellular alterations observed in inflammatory diseases of ocular surface.