Abstract
Abstract: :
Purpose: To determine if ocular surface staining with lissamine green–impregnated strip is equivalent to staining with 1% lissamine green solution. Methods: We performed a prospective, double–masked, two–period cross over study. A series of ten patients with dry–eye disease (selected to create a sample of patients with mild to severe disease) were randomized to either drop or strip application of lissamine green. Three observers, masked to the application method, independently graded the conjunctival staining using the NEI/Industry Workshop Scale. The patients’ eyes were then irrigated free of stain and lissamine green was applied by the alternate method for repeat grading of the stained conjunctiva. A second trial was also performed by another independent observer. Statistical analysis was by a non–parametric paired t–test (Wilcoxon signed–rank test). Null hypothesis was that the two application methods were equivalent, and type 1 error was set at 5%. For each patient, we first averaged the scores measured by the three observers for each conjunctiva section, and then calculated the mean conjunctiva score over all six conjunctiva sections for each eye examined. The mean scores of eyes stained with lissamine 1% solution were then compared to the same eyes stained with lissamine–impregnated strip using the Wilcoxon signed–rank test. Results: Our results show no statistically significant difference between the grading of the ocular surface using lissamine 1% solution and lissamine green–impregnated strip (p=0.850, 0.791 (OD,OS) for trial 1 and p=0.910, 0.225 for trial 2). Conclusions: Lissamine green–impregnated strips can reliably be used as a substitute for lissamine 1% solution in the accurate diagnosis and follow–up of patients with dry eye if adequate volume of solution is applied to the strip.
Keywords: cornea: tears/tear film/dry eye