Fundus Autofluorescence Change as an Early Indicator of Treatment Effect of Brachytherapy for Choroidal Melanomas

Abstract

Background: Early confirmation of the effect of brachytherapy for choroidal melanoma showing that tumour coverage is valuable. The irradiated retinal pigment epithelium (RPE) commonly develops atrophy. This study compares the fundus autofluorescence (AF) changes to the development of RPE atrophy following brachytherapy.

Methods: Retrospective study of 19 patients treated with ¹⁰⁶Ru and 2 with ¹²⁵I plaques with either a 3- or 6-month follow-up period. Ultra-widefield (UW) composite colour and AF images were obtained with Optomap 200Tx and interpreted as complete, partial, or no RPE changes and complete or partial hyperautofluorescence, hypoautofluorescence, or isoautofluorescence.

Results: At the 3-month follow-up, 9 of 13 patients (69%) (95% confidence interval [CI], 0.389-0.896) treated with ¹⁰⁶Ru plaques developed complete homogenous hyperautofluorescence surrounding the tumour, but only 1 of 13 (8%) (95% CI, 0.004-0.379) developed complete RPE atrophy at the same time point. Six patients in the ¹⁰⁶Ru plaque group had their first follow-up with UW imaging at 6 months. Four of them developed homogenous hyperautofluorescence and none developed complete RPE atrophy around the tumour. The 2 patients treated with ¹²⁵I did not demonstrate any clear RPE or AF changes.

Conclusion: The effect of ¹⁰⁶Ru plaque treatment on fundus UW imaging is detected as homogenous and well-demarcated hyperautofluorescence before visible RPE atrophy.

Keywords: 106Ru plaque; Brachytherapy; Choroidal melanoma; Fundus autofluorescence; Ultra-widefieldfundus imaging.

Fig. 1

A1–2, B1–2, C1–2, and D1–2: Development of hyperautofluorescence and RPE atrophy around a choroidal melanoma (T1a) following brachytherapy in a patient treated with ¹⁰⁶Ru plaque. The subretinal fluid on the baseline UW FA image appears hyperautofluorescent and is indicated by stars (A1). The subretinal fluid was not clinically detected following brachytherapy (B1, C1, and D1). The homogenous hyperautofluorescence (white arrows) surrounding the tumour is seen earliest at the 3-month follow-up (B1). A yellow area matching the hyperautofluorescent area in B1 is seen in B2, but without a clear development of RPE atrophy. The development of incomplete RPE atrophy (black arrow) can be seen at the 6-month follow-up (C2), and a clear RPE atrophy is seen at the 9-month follow-up (D2).