STUDY OF EPITHELIAL PHENOTYPE AFTER PTERYGIUM EXCISION BY USING CONJUNCTIVAL IMPRESSION CYTOLOGY

Abstract

Purpose: To compare the process of conjunctival epithelial regeneration after three types of pterygium excision procedures.

Methods: Twenty-two patients (27 Eyes) with primary progressive pterygium were randomly assigned to the bare-sclera procedure (group I, 9 eyes), pterygium excision with amniotic membrane transplantation (group II, 9 eyes), and pterygium excision with conjunctival autografting (group II, 9 eyes). Controls were healthy fellow eyes and ten eyes of age and sex matched subjects. Conjunctival impression cytology was performed with Millipore filter paper (0.025-0.22 microns) of 3 x 3 mm pieces pre and postoperatively at 2 weeks, 1, 3, 6, and 12 months. The nucleus to cytoplasm ratio of goblet epithelial cells and goblet cell density in pterygium area were calculated and compared between groups.

Results: Pterygium excision wounds healed in a similar four-stage process in all the groups, but at different rates. The nucleus-to-cytoplasm N/C ratio was highest at 2 weeks, 1 month, 3 months in group III, II, and I respectively, before gradually returning to control levels. Pre-operatively, the goblet cell density GCD in treated eyes was twice than controls (p 0.001) but fell to zero post-operatively. Goblet cells first appeared in group III, followed by group II. At 12 months, the mean GCD in group III was not significantly different from controls, whereas in group I and II were still less than controls (P 0.02)

Conclusion: Conjunctival autograft prevents pterygium recurrence more effectively than AMT. Impression cytology revealed a marked decrease in goblet cell density in the bare sclera and AMT cases while goblet cells returned to normal size, shape, and density in conjunctival autograft group. Even 1 year after surgery, the ocular surface remained abnormal with respect to epithelial phenotypes in all techniques.