gms | German Medical Science

Radiation therapy in cases of malignant melanoma of the conjunctiva may lead to irritation of the ocular surface, the tear film and their annexes. As a new therapeutic approach in eyes with special indications proton-beam radiation is used in Essen in order to treat curatively. In this study we examined 10 patients concerning ocular surface integrity with conventional methods who underwent proton beam radiation between 1996 and 2002. Further, we give an outlook on future studies.

Eight of the ten cases which were previously treated with other adjuvant methods showed tumour recurrences before the treatment with proton beam radiation. After a standard ophthalmological examination, a fluorescein-clearance test (FCT), the tear film break up time (BUT), a transillumination of the eye lids, vital staining with fluorescein and rose bengal and an impression cytology (IPC) of the conjunctiva were performed.

The follow-up was 17 to 87 months (mean 40,9±20,1). In six cases more than 50% of the upper and lower eye lid were included in the radiation field. All of these cases showed moderate to severe sicca-symptoms. The FCT was normal in three cases, three patients showed mild and four patients severe changes in the quantity of tear production. The IPC revealed squamous metaplasia of conjunctival cells and reduction of conjunctival goblet cells in 9/10 cases. Spindle-shaped cells and a pathological change in the nucleus/cytoplasm-ratio were frequent findings after proton beam radiation. Transillumination of the eye lids showed distinct atrophy of meibomian glands in the areas included in the radiation-field.

Squamous metaplasia of conjunctival epithelia indicates a radiogenic and long-lasting disturbance of differentiation of the conjunctival epithelial cells. The tear film instability correlates with the loss of mucin-expressing goblet cells and meibomian gland dysfunction. Two questions are crucial in regard to ocular surface integrity: 1. Is it possible to detect mediators of inflammation and which influence do they have on the radiation-induced disturbances of the tear film and the ocular surface. 2. How is the tear-film stabilised and how do other tear-film-associated proteins act after radiation therapy. These questions will be raised in future studies. We will therefore analyse the expression of different mediators of inflammation in the tear film. In addition we will use impression cytology samples of the conjunctiva to examine the gene expression of various tear-film associated proteins as mucins, TFF-peptides (trefoil factor) and defensins (human β-defensin 2) and of various differentiation associated proteins (kallikrein, keratins etc.) by means of quantitative real-time-PCR. The herein obtained results might reveal clinically relevant insights concerning radiation-induced alterations of the ocular surface.