Choroidal osteoma associated with focal choroidal excavation

Choroidal osteoma is a rare benign lesion consisting of mature bone that replaces choroidal tissue. The tumor can lead to serious vision-threatening complications related to atrophy of the overlying retina and secondary choroidal neovascularization. Focal choroidal excavation (FCE) is characterized by an area of choroidal ectasia in an eye without evidence of posterior staphyloma. Although FCE may represent a congenital abnormality, it has also been reported in association with various chorioretinal disorders and inflammatory chorioretinopathies. We describe the case of a 74-year-old woman complaining of metamorphopsia of sudden onset in her right eye. Best-corrected visual acuity was 20/20 and fundus examination showed a choroidal osteoma at the posterior pole associated with FCE involving the fovea. Interestingly, spectral domain optical coherence tomography disclosed the presence of a steep slope along the superior border of the FCE and a shallow slope along the inferior one. Choroidal osteoma is commonly diagnosed in late childhood, and in about half of the cases shows evidence of growth and decalcification with aging. It has been speculated that progressive focal decalcification may lead to structural changes inducing the FCE.