Influence of Corneal Staining in Rabbits on the Evaluation of Eye Irritation Test Results

Objective To observe the influence of the staining phenomenon after fluorescein sodium staining on eye irritation in normal rabbits. Methods In the experimental rabbit eye irritation test conducted with sodium chloride eye drops, Siwei Zhenceng Bingpeng eye drops, sodium hyaluronate eye drops, sodium cromoglycate eye drops, and compound aspartate eye drops (4 in each group, half male and half female), the left eyes of rabbits were administered normal saline (self-negative control) and the right eyes were administered the experimental medicine; the eyes were stained with 1% sodium fluorescein, and eye irritation was observed and scored using slit lamp microscope for 31 days. Morphological changes of corneal epithelial staining were recorded and the incidence of staining was calculated. After the observation, the eyeballs and Hasselblad glands were examined histopathologically, and the staining rate of the left eye was compared with that of the right eye which was administered the corresponding medicine. Results Neither eye had any irritation symptoms; the scores were 0, and the total incidences of corneal staining were 3% (left) and 1% (right), respectively. There was no significant difference between the two groups (P > 0.05). Corneal epithelial staining showed single-spot staining, scattered dot, localized, or large areas of fusion staining. No histopathological changes were found in the eyeballs or Hasselblad glands, and the results were evaluated as non-irritative. Conclusion The irregularity of corneal epithelial staining in rabbits did not influence the results of the ocular irritation test.