Choroidal osteoma

Choroidal osteoma is an acquired, benign tumour of the choroid which usually forms near the optic disc or macula. Histologically, it consists of irregular spicules of mature cancellous bone within a vascular connective tissue stroma.

It is diagnosed most often in young women, and produces variable symptoms relating to its size and location. Most choroidal osteomas do not require active intervention.

Choroidal neovascularisation occasionally develops at the margins of long-standing lesions, and is treated with laser photocoagulation to minimise complications including fluid leakage, bleeding and fibrosis.

SYMPTOMS

A common presentation of lesions in the vicinity of the macula is variable loss of central vision with distorted shapes (metamorphopsia, caused by disruption of the spatial relationship between photoreceptors). When central vision is spared, patients occasionally notice visual field defects corresponding to the location of the tumour. Sudden loss of central vision may occur when choroidal neovascularisation results in serous or haemorrhagic retinal detachment involving the macula.