Clinical characteristics of pachychoroid-associated choroidal ossification.

PURPOSE: To characterize the multimodal imaging features of pachychoroid-associated choroidal ossification (PACO), a newly proposed entity, in eyes with pachychoroid diseases. METHODS: This retrospective case series included 12 eyes in 11 patients with PACO and 14 age-matched eyes with choroidal osteoma as a control group. Lesions were characterized using multimodal fundus imaging, which included B-scan ultrasonography. The subfoveal choroidal thickness (SFCT) and the maximum choroidal vessel diameter (MCVD) were manually measured on optical coherence tomographic images. RESULTS: PACO lesions exhibited a hyperechoic appearance with posterior shadowing on B-scan ultrasonography. Distinct multimodal imaging features included tortuous vascular tufts on indocyanine green angiography and an abnormal vasculature within the lesion on optical coherence angiography. Among the 12 eyes, 7 eyes had ossified lesions at initial presentation, including 6 eyes with chronic central serous chorioretinopathy (CSC) and 1 eye with polypoidal choroidal vasculopathy, whereas PACO developed during follow - up in the remaining 5 eyes. In 3 eyes with CSC, PACO lesions developed on fibrin sites over microtears in the retinal pigment epithelium accompanied by dilation of the underlying choroidal vessels. PACO was more frequent in males (P = 0.023) and was characterized by a longer interval from symptom onset to presentation of PACO lesions (P = 0.004), shorter maximum tumor linear dimension (P = 0.004), decreased tumor thickness (P < 0.001), increased SFCT (P < 0.001), and larger MCVD (P < 0.001) compared with the control eyes with osteoma. During the mean follow-up period of 42.50 ± 44.35 months (range 3‒131 months), 10 lesions decreased in height but increased in length. New ossified lesions emerged in the contralateral eye in 2 patients. CONCLUSIONS: PACO is an acquired choroidal ossification secondary to pachychoroid diseases, distinct from choroidal osteoma and fibrosis. Despite the lack of histologic investigation, our findings may enhance our understanding and recognition of the pathophysiological mechanisms involved in choroidal ossification.