Surface Mucin Changes in the Rabbit Dry Eye Model Using a Modified Impression Cytology Technique

Abstract

Abstract: : Purpose. To study the ocular surface changes in a rabbit dry eye model using a modified impression cytology technique.Methods: Aqueous tear production was inhibited by repeated systemic administration of atropine sulphate 1.0% to 5 New Zealand white rabbits (2.1–2.5 kg). Ocular surface changes were evaluated by impression cytology using Nitrocellulose (Sartorius AG.37070, Göttingen, Germany) filter paper with a pore diameter of 0.45 µm which were kept in distilled water overnight and dried the next day to increase cell pick–up. Samples were kept in peroxide for 5 min, then they were washed with distilled water for 5 min, and they were stained with periodic acid–Schiff (PAS) according to the protocol: 1. Hydrated with distilled water (5 min), 2. Oxidized in 0.5 periodic acid (6–8 min), 3. Rinsed in distilled water (5 min), 4. Stained with Schiff’s reagent (3–4 min), 5.Rinsed in tap water (5 min), 6.Dehydrated with 95% ethanol (2 min), 7. Permanently mounted on slides. The change in the morphology of the nitrocellulose filter paper was evaluated using scanning electron microscopy (JEOL 6400 JSM– SEM ). Results: Cell pick–up increased dramatically using the modified impression cytology technique. Mean temporal and superior bulbar conjunctival goblet cell densities of the induced dry eyes of the rabbits were found significantly decreased according to the normal rabbit eyes before atropinisation (p<0.05). The pore size of the filter paper seemed unchanged using SEM. Conclusions: In this study, a dry eye state was created using repeated intramuscular (i.m.) injections of atropine in the rabbit. Standard impression cytology technique did not reveal much information about the ocular surface, while the modified technique improved cell pick–up from the rabbit ocular surface. Electrostatic change in the filter paper was presumed to be responsible for better cell pick–up.

Keywords: conjunctiva • cytology • inflammation