Indocyanine green angiography and fluorescein angiography of malignant choroidal melanomas following proton beam irradiation

Abstract

The vascularisation features of intraocular tumours may be characterised by indocyanine green angiography (ICG-A) and fluorescein angiography (FA). Proton beam irradiation is an established method of treating malignant melanoma of the choroid. The aim of this study was to describe the vascularisation features of small choroidal melanomas and to examine the influence of proton beam irradiation on these tumours. We examined 39 choroidal melanomas by ICG-A and FA from 1998 to 2001 in a prospective study. The tumours had a mean prominence of 3.65 mm (1.2-7.5 mm) and a common feature of all was their parapapillary or paramacular localisation. Angiography was always performed immediately before proton beam radiotherapy and at intervals of 3 months, half a year and 1 year thereafter. Two hundred and forty angiographies were analysed in total. Intra-tumoral vessels could be visualised in 89% of all tumours by ICG angiography but in only 33% by FA. Neither ICG-A nor FA detected changes 3 months after irradiation; however, ICG-A disclosed strong leakage from vessels in the tumour area after 6 months. These changes increased markedly after 12 months and were also visible by FA. A disadvantage of FA, however, was the faster escape of dye from the vessels, which caused rapid leakage in the tumour area and meant that details could no longer be demonstrated. ICG-A and FA detect marked vascular changes within the tumours examined.