Impression cytology study of conjunctival epithelial phenotypes on the healing ocular surface after pterygium excision

Purpose. To compare the process of conjunctival epithelial regeneration after three types of pterygium excision procedures. Methods. Thirty-eight patients (45 eyes) with primary pterygium were randomly assigned to a bare-sclera procedure (group 1, 15 eyes of 12 patients), bare-sclera with intraoperative mitomycin C (MMC 0.02% for 30 seconds; group 2, 15 eyes of 14 patients), or pterygium excision with conjunctival autografting (group 3, 15 eyes of 12 patients). Controls were healthy fellow eyes and seven eyes of age- and sex-matched subjects. Impression cytology was performed preoperatively, at 1 and 2 weeks, and at 1, 3, 6, and 12 months after surgery. The nucleus-to-cytoplasm (N/C) ratio of nongoblet epithelial cells and goblet cell density (GCD) in the pterygial area were calculated and compared over time across treatment groups. Results. Pterygium excision wounds healed in a similar four-stage process in all groups, but at different rates and with different final results. The N/C ratio was highest at about 1 month postoperatively in groups 1 and 2 and at 2 weeks in group 3, before gradually returning to control levels. Preoperatively, the GCD in treated eyes was almost twice that in control eyes (p = 0.001) but fell to zero immediately postoperatively. Goblet cells first appeared (with the most rapidly increased density) in group 3, followed by group 1. At 12 months, the mean GCD in groups 1 and 3 were not significantly different from those in controls, whereas the mean GCD in group 2 was still less than that of control (p = 0.02). Conclusions. Healing of conjunctiva is delayed by MMC and is promoted by autografting. Even 1 year after surgery, the ocular surface remains abnormal with respect to epithelial phenotypes in eyes treated by any of the three techniques.