Analysis of ocular surface alterations following proton beam radiation in eyes with conjunctival malignant melanoma

Background. In cases of large, diffuse or multilocular growth pattern of conjunctival melanoma, proton beam irradiation can serve as an alternative therapy to exenteration. In extended tumours, ocular surface problems can result after therapy. In this study we examined ocular surface integrity of ten patients who underwent proton beam radiation between 1996 and 2002. Methods. The patients were examined during their follow-up. Eight of the ten cases who underwent proton radiotherapy were recurrent tumours, which were previously treated with other adjuvant therapies. We performed a standard ophthalmological examination and detailed tear film diagnostics. Results. The follow-up was 17-87 months (mean: 40.9 +/- 20.1). In six cases more than 50% of the upper and lower eyelids were included in the radiation field. All of these cases showed moderate to severe sicca symptoms. The impression cytology revealed squamous metaplasia of conjunctival cells in nine of ten cases. Conclusions. Squamous metaplasia of conjunctival epithelia indicates a radiogenic, persisting disturbance of differentiation of the conjunctival epithelial cells. The tear film instability correlates with the loss of mucin-secreting goblet cells and meibomian gland dysfunction.