ObjectiveTo observe and analyze the image characteristics of eyes with choroidal osteoma using swept-source OCT (SS-OCT).MethodsSeventy-three eyes of 61 patients with choroidal osteoma were enrolled in the study, including 17 males (20 eyes) and 44 females (53 eyes) with an average age of 33.5±12.7 years. Single tumor was found in 71 eyes and multiple tumors were found in 2 eyes. All patients received examinations of slit lamp ophthalmoscope, color fundus photography, fundus autofluorescence, fluorescein angiography and/or indocyanine green angiography, B-scan ultrasonography and/or computerized tomography. Tumor features were characterized using SS-OCT.ResultsAmong 75 tumors of 73 eyes, the osteoma was completely calcified in 7 tumors, completely decalcified in 5 tumors and all the other tumors were composed of calcified and decalcified portions. SS-OCT revealed normal inner retina in all the calcified areas of tumors and abnormal outer retina including external limiting membrane, ellipsoid zone, interdigitation zone and RPE in some cases. Whereas the outer retina and RPE showed abnormality in the decalcified areas of all cases. The choriocapillaris was invisible in all cases and most of the medium and large caliber vessels showed thinning or nonvisibility. Choroidal osteoma revealed a sponge-like appearance (n=39), loofah sponge appearance (n=11), lamellar pattern (n=10), mixed (n=12) and irregular patterns (n=5). Other unique features included horizontal lamellar lines (n=71), hyperreflective horizontal lines (n=47) and hyporeflective tubules (horizontal:n=39, vertical:n=42, circular:n=41) within choroidal osteoma. Hyperreflective tumor-like tissues were also detected above the disrupted Bruch’s membrane. The sclero-choroidal junction was detectable in all tumors and a posterior ciliary vessel penetrating the sclera was also seen.ConclusionsSS-OCT clearly reveals characteristic appearances of choroidal osteoma as sponge-like, loofah sponge, lamellar pattern, mixed and irregular patterns, with unique features of horizontal lamellar lines, hyperreflective horizontal lines and hyporeflective tubules within osteoma. Hyperreflective tumor-like tissues were detected to grow above the disrupted Bruch’s membrane.