Background: Chronic inflammation in pterygium occurrence has not been explained. Whether damaged limbal basal epithelial cells are associated with pterygium occurrence in black Africans is not clear. Objective: To explain chronic inflammation in pterygium, and to clarify whether damaged limbal basal epithelial cells were associated with pterygium occurrence in black Africans. Methods: Chronic inflammatory changes and damaged limbal basal epithelial cells were assessed in 59 samples. Results: Chronic inflammatory cells were present in 59 pterygia. Inflammatory cell count in 5 (27.8%) of 18 small pterygia was >200 (high) while in 22 (53.7%) of 41 large growths was <200 (low); p = 0.25. The proportion of pterygia with high counts tended to increase with pterygium extent. Twenty (33.9%) of 59 pterygia recurred after surgery. Ten (50%) of 20 samples had high cell counts and 10 (50%), low counts; p = 0.40. P53 expression was detected in 11 (18.6%) of 59 pterygium samples and 5 (71.4%) of 7 controls; p = 0.007. MMP 1 staining was present in 14 (23.7%) of 59 sections and 5 (71.4%) of 7 controls; p = 0.02. MMP2 in 16 (27.1%) cases and 5 (71.4%) controls; p = 0.03. MMP3 was overexpressed in 16 (27.1%) of 59 cases and 5 (71.4%) controls; p = 0.03. Conclusions: Mild chronic inflammation has a tendency to be more frequent than severe inflammation in pterygia. It is clear that damaged limbal basal epithelial cells are unlikely to be related to pterygium occurrence.

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Pterygium is a wing-shaped fibrovascular growth of the conjunctiva across the limbus onto the cornea. 1 Although a hereditary influence on pterygium formation is recognised 1 and a report of possible genetic influence in white South Africans has been published, 2 little is known about these factors in black African populations. Pterygia are widely believed to be due to excessive exposure to sunlight, 3,4 and a long duration of ultraviolet radiation has been reported to be responsible for its development. 5 The use of tobacco, 6 a poor tear film, 7 lower levels of education and skills, 6 ethnicity, 8 exposure to dust, 8 malnutrition 4 and chronic ocular surface inflammation 8 have been reported or proposed as associations with pterygium occurrence. The relative importance of these factors has not been described in rural black Africans. This report is confined to investigating possible genetic factors and dry eye, which were the main associations found. Ethical clearance was obtained from the institutional research ethics committees. We prospectively interviewed 71 patients and 71 age-and sex-matched controls in the Mankweng Eye Unit in Polokwane. Patients with ocular surface malignancy and pseudo-pterygium were excluded. Consent was obtained and participants were shown three photographs of eyes with pterygia (Fig. 1) and asked questions similar to those used in a previous study. 2 The patients were shown the photographs and asked if they had ever seen a person with such a growth on the eye. If they replied in the affirmative, they were asked if that person was a relative and if so what their relationship with the person was. Tear-film stability was assessed using a previously reported procedure; 7 after application of 5% fluorescein, the cornea was assessed for areas of dark spots or streaks in between the blinks. The mean age of the participants was 45 years (standard deviation 10.65), with a range of 22-65 years. There were nearly three times as many females as males in the series. There was a positive family history of pterygium in 36% of cases and 10% of controls. A positive history was almost 5 times as common in cases as in controls. This was statistically significant (p<0.05, chi-square test). The tear film was unstable in 7% of cases and 17% of controls. An unstable tear-film was 4 times more common in controls than in cases, and this was significant (p<0.05, chi-square test). A positive family history implies hereditary predisposition. 2 It was the only positive factor associated with the formation of pterygia in this study. In Australia 38% of patients admitted for pterygium surgery compared with 8-12% of controls admitted for other conditions had a family history of the growth. 9 In South Africa 30-35% of urban predominantly white individuals who had attended an ophthalmic practice because of pterygium had a positive family history. 2 An unstable tear film (dry eye) was not associated with pterygium in this study, and this lack of association has previously been reported