APR 18, 2013
This prospective study found that gamma-knife radiotherapy significantly affects the ocular surface and tear function, and increases dry eye symptoms and signs in patients with choroidal melanoma.
The authors analyzed subjective symptoms and dry-eye parameters after stereostatic, single-fraction gamma-knife radiosurgery (median dose, 30 Gy) for choroidal melanoma in 36 patients with a median age of 62 years.
Subjective dry-eye symptoms and lissamine green staining of the ocular surface were significantly higher three months postoperatively in treated eyes compared to fellow eyes. The authors write that this early increase may be caused by the fixation of the globe using transconjunctival sutures. The post-radiation topical therapy also could have had a negative influence on the ocular surface and tear film. These differences remained significant 24 months after radiosurgery.
Central corneal sensitivity in the treated eyes decreased, and the difference between the treated eyes and fellow eyes compared with pretreatment values was significant after 12 months and 24months. Fluorescein staining of the cornea also deteriorated in treated eyes, with the difference between treated and fellow eyes increasing significantly after 12 months, 24 months and 36 months compared with pretreatment values. Treated eyes also showed significantly reduced tear fluid production at 24 months and 36 months compared to untreated eyes.
Dosage high enough to affect the lacrimal gland was significantly correlated with fluorescein staining, lissamine green staining score and Schirmer test values in treated eyes compared with the fellow eyes 24 months after irradiation.
They write that until now, no special effort has been made to spare the lacrimal gland during treatment planning, but since they found a correlation between dose size and dry-eye signs, they recommend limiting the dose as much as possible.
They conclude that tear film and ocular surface evaluation should be performed before radiation and during follow-up in order to detect acute and chronic complications and to initiate treatment on a timely basis. Patients should be informed about the high risk for development of dry-eye symptoms after gamma-knife radiosurgery and the need for long-term treatment.