Abstract
Abstract: :
Purpose: Ocular surface staining is a critical variable in clinical trials for evaluation of dry eye disease. Lissamine green is a dye that is being increasingly used to detect ocular surface disease. The application parameters and the method of evaluation have, however, neither been validated nor standardized so far. The purpose of this study was to determine the optimal parameters of ocular surface staining by lissamine green 1% solution in dry eye disease. Methods: We performed a prospective, masked, study to evaluate patients with various degrees of dry eye disease. We investigated the ocular surface staining on these patients by use of topical lissamine green 1% stain to determine repeatability of observations. Four observers, with varying clinical experience in evaluating lissamine green staining, provided randomized grading of ocular surface stain using the Oxford scheme. Three different volumes of instilled stain (5 µl, 10 µl, 20 µl) were used in a masked fashion. Evaluations were done with and without the use of a red barrier filter during slitlamp biomicroscope illumination with white light. Statistical analysis of results was performed using the kappa statistic with p values of 0.05 limits. Results: Excellent correlation across all observers was seen when 10 µl or 20 µl volumes of stain were instilled, with and without the red filter. Variability was noted with the 5 µl volume, however. The red filter was particularly valuable in improving and facilitating the detection of corneal staining with lissamine green. The optimal observation time for evaluation was found to be between one and four minutes after instillation. Early observation (at one minute), using 20 µl volume, could be confounded by residual pooled stain that made the evaluation more difficult, particularly in patients who had prior punctal occlusion. Conclusions:Lissamine green 1% solution is a reliable and well tolerated stain for detecting ocular surface staining. Its use is optimal with 10 to 20 µl of instilled volume, observed in low to moderate intensity white light of the slitlamp, between one and four minutes following instillation. The use of a red barrier filter improves detection of staining, particularly in the cornea.
Keywords: cornea: tears/tear film/dry eye • cornea: clinical science • conjunctiva