Choroidal osteoma is a benign tumor, predominantly affecting young women. More than 50% patients end up with visual acuity of 6/60 or worse, primarily because of choroidal neovascularization (CNV). Conventional photocoagulation is rarely useful.1 We successfully treated a subfoveal CNV in choroidal osteoma with transpupillary thermotherapy (TTT).

Case report

A 22-year-old woman presented with blurred vision in left eye for 12 days. Best-corrected visual acuity was 6/6 in the right eye, and 6/36 in the left. Systemic, serological, and urinary evaluations were unremarkable. Fundus examination showed an orange–white peripapillary subretinal lesion in both eyes, and a subfoveal CNV in the left eye (Figure 1a). Ultrasonography showed a high-echogenic lesion with acoustic shadowing (Figure 1b). Computed tomography (CT) revealed a bone-density plaque. Fluorescein angiography demonstrated a classic subfoveal CNV in the left eye (Figure 2a). The options of photodynamic therapy (PDT), TTT or observation were explained to the patient. After her informed consent and approval from the Institutional Review Board, TTT was carried out on a slitlamp-mounted 810 nm diode laser. The treatment end point (no visible retinal greying) was predetermined with test burns beyond the inferior arcade. A single 2 mm burn of 250 mW power was delivered for 1 min. Treatment was repeated using similar parameters at 3 and 6 months for residual angiographic leakage. A complete resolution of CNV was observed (Figure 2b) and maintained over the next year; visual acuity stablilized at 6/60.

Figure 1
figure 1

(a) Fundus photograph of the left eye showing peripapillary choroidal osteoma, with subfoveal choroidal neovascular membrane (CNV). (b) Combined A and B scan ultrasonogram of the left eye demonstrates high reflectivity of the osteoma, persisting at a low gain.

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Figure 2
figure 2

(a) Late-phase fluorescein angiogram of the left eye shows hyperfluorescence of a classic subfoveal CNV with adjacent blocked fluorescence due to subretinal blood; peripapillary choroidal osteoma shows a granular staining. (b) The CNV regressed completely after the third session of transpupillary thermotherapy.

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Comment

In the largest published series on choroidal osteoma, the major cause of visual loss was CNV. About half were subfoveal and were only observed. Extrafoveal CNV responded poorly to conventional photocoagulation, probably due to depigmentation of the retinal pigment epithelium (RPE), which reduced uptake of laser energy.1 Extrafoveal lesions have been successfully treated by PDT, but it has not been attempted on subfoveal CNV.2, 3 Although PDT is theoretically safer (nonthermal) and more effective (not dependent on RPE density) than TTT, complete ablation of CNV required multiple sessions, and was associated with a drop in vision in one report.3 Similarly, surgical excision of subfoveal CNV was reported to be successful, but visual outcome was poor.4 There is another recent report on TTT for osteoma-induced subfoveal CNV, which resolved with stable vision following a single treatment session.5 A report has also mentioned TTT for a fibrovascular RPE detachment, but treatment parameters and outcome were not detailed.6 TTT has been successfully used for subfoveal CNV due to age-related macular degeneration and other aetiologies.7, 8, 9 The safety and efficacy of subthreshold TTT has been histopathologically demonstrated.10 In spite of three treatment sessions, our patient maintained a stable visual acuity, similar to the previous report.4 We propose that TTT may be a useful treatment alternative to submacular surgery or PDT for subfoveal CNV in choroidal osteoma and therefore needs to be investigated further in larger studies.