Choroidal Osteoma With Choroidal Excavation Due to Decalcification Five Years After Photodynamic Therapy: A Case Report

A choroidal osteoma (CO) is a relatively rare, benign tumor with ossification that develops in the choroid and undergoes enlargement and decalcification in its natural course. Photodynamic therapy (PDT) is used to induce decalcification, but there are few reports on individual cases treated with PDT. A 47-year-old Japanese man who had reduced decimal visual acuity (VA) of the right eye to 0.7 due to a CO away from the fovea was treated with PDT. The PDT resulted in a partial decalcification of CO, and the visual acuity improved to 1.0. However, the tumor slowly expanded, eventually reaching the central fovea. Decalcification and focal choroidal excavation occurred during this natural course of the disease. Although his metamorphopsia worsened, his VA was maintained at 1.0. This case highlights that a CO partially decalcified after PDT can still enlarge and decalcify over several years. These findings indicate the need for careful and continuous monitoring of eyes with a CO.