Indocyanine green angiography in choroidal osteoma.

Background: Choroidal osteoma is a rare choroidal tumor; knowledge of its indocyanine green characteristics is limited.

Methods: The fundus photographs and the fluorescein and indocyanine green angiograms of three patients were reviewed. Each patient was examined at least twice with a follow-up varying from 10 to 60 months.

Results: Late-phase fluorescein angiograms allow assessment of the extension of the osteoma as it is variably hyperfluorescent due to tumor staining combined with a variable degree of overlying retinal pigment epithelial changes. The hypofluorescent area observed in the early phase of the indocyanine green angiogram corresponds with the extent of the osteoma but the borders may be difficult to demarcate. In the late phase of the indocyanine green angiogram, hypofluorescence due to choriocapillaris loss and hyperfluorescence due to leakage from abnormal choroidal vessels are combined. Infrared angiography high-lights abnormal choroidal vessels and vascular spiders present on the tumor surface. It is difficult to differentiate these choroidal vascular anomalies from subretinal neovascularization.

Conclusions: We find no homogeneous pattern either on fluorescein or on infrared angiography. The findings may change with follow-up, indicating changes within the tumor or the surrounding tissue that are still poorly understood.