[Abnormal epithelial differentiation and tear film alteration in pterygium]

To investigate the differentiation and proliferation of the conjunctival epithelium and tear film function in pterygia.

It was a retrospective study. Fifteen patients (15 eyes) who underwent excision for pterygium were enrolled in this study. Immunostaining for K10, K14, K19, MUC5AC, K16, Ki67 and P63 was performed on the pterygial epithelium and normal conjunctival epithelium. Schirmer I test was performed, and the tear film break-up time (BUT) was evaluated just prior to and 6 months after surgery. Multi-factor regression analysis was assessed to observe if there is a correlation between pterygial growth and tear film function.

The average absorbency of K19 and MUC5AC immuno-staining all significantly changed (3727.86 ± 2544.73 vs. 25 528.00 ± 12 901.06, 2080.48 ± 2340.17 vs. 7182.51 ± 3069.20, t = 9.261,3.538, P < 0.05), and increased in K10 and K14 in patients with pterygia compared with normal conjunctivae keratin (2017.51 ± 2114.3 vs. 0, 6027.5 ± 1058.32 vs. 2123.28 ± 1249.09, t = -6.151, P < 0.05). Furthermore, pterygial epithelium showed activated proliferation, evidenced by significantly up-regulated expression of K16, P63 and Ki67 compared to normal control. The Schirmer I test did not indicate any significant differences pre- and post-operatively. However, the BUT was significantly prolonged 1 month post surgery compared to pre-surgery (t = -4.222, P < 0.05).

This study indicates that abnormal epithelial differentiation and proliferation are present in pterygium , which is characterized by squamous metaplasia, accompanied with instability of tear film and normal basic tear secretion.