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Sir,

Case report

A 50-year-old white woman was referred for evaluation of an amelanotic choroidal lesion in the left eye. She had presented to her ophthalmologist with a recent onset of blurred vision of 2 weeks duration. Her past ocular history, medical history, and family history were negative. On examination, the best corrected visual acuity was 6/6 in the right eye and 6/9 in the left eye. Anterior segment examination of both eyes and fundus evaluation of the right eye was unremarkable. Ophthalmoscopic evaluation of the left eye revealed a solitary amelanotic choroidal lesion in the superior macular region. The lesion was about 6 mm × 5 mm in basal dimension and was minimally elevated. The margins were scalloped. Overlying retinal haemorrhages and subretinal fluid, which extended into the foveal region, were also observed (Figure 1a). B-scan ultrasonography demonstrated high reflectivity at the level of the choroid suggestive of calcium deposition (Figure 1b). On fluorescein angiography the lesion revealed early patchy hyperfluorescence and late staining. In addition, overlying the posterior aspect of the choroidal lesion, lacy hyperfluorescence indicative of extrafoveal classic choroidal neovascularization was present (Figure 1c). A diagnosis of choroidal osteoma with choroidal neovascularization was made. Photodynamic therapy (PDT) according to the TAP study protocol was performed without any complications.1 A total of three sessions were performed at 6 weeks interval under fluorescein angiographic guidance. Following completion of therapy, the vision improved to 6/6. Ophthalmoscopically a greyish subretinal fibrotic membrane was noted in the treated area with total resolution of subretinal fluid and retinal haemorrhages (Figure 1d). Complete closure of choroidal neovascularization was seen on fluorescein angiogram (Figure 1e). At a 6-month follow-up visit, additional PDT was performed to treat a posterior marginal recurrence. She has remained stable for 6 months following the last PDT with a final visual acuity of 6/36.

Figure 1
figure 1

(a) Fundus photograph of the left eye. An amelanotic choroidal lesion with scalloped margins is evident in the superior macular region. Note retinal hemorrhages and sub retinal fluid involving the foveal region. (b). B-scan ultrasonograph demonstrating high reflectivity at the level of the choroid suggestive of calcium deposition. (c). Intravenous fluorescein angiogram (laminar venous phase). Patchy hyperfluorescence in the region of choroidal osteoma (arrows) and lacy hyperfluorescence (arrowheads) indicative of extrafoveal classic choroidal neovascularization. (d). Fundus photograph of the left eye following completion of PDT. A greyish subretinal fibrotic membrane is present in the treated area. Note resolution of retinal hemorrhages and subretinal fluid. (e). Intra venous fluorescein angiogram (laminar venous phase) following completion of PDT. Note the absence of lacy hyperfluorescence.

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Comments

The term choroidal osteoma was coined by Gass in 1978 when he described four healthy young women with characteristic ophthalmoscopic findings of slightly elevated, yellowish, juxtapapillary, choroidal tumour with sharp geographic borders.2 These tumors demonstrate evidence of bone formation in the choroid and are believed to be choristomatous in origin.3 The majority of patients with choroidal osteoma maintain good vision. However, there is increasing probability of loss of vision with increasing duration of follow-up. In a follow-up study of 36 patients, the probability of loss of visual acuity (6/60 or worse) was more than 50% by 10 years.4 Choroidal neovascularization is the most frequent cause of visual loss in choroidal osteoma with more than half of the patients expected to develop choroidal neovascularization.4, 5

Owing to lack of pigment in the tumour and atrophy of overlying retinal pigment epithelium, laser photocoagulation has limited efficacy (25%) in the treatment of choroidal neovascularization secondary to choroidal osteoma.4 PDT is independent of the intrinsic pigmentation and has the advantage of sparing overlying retina. Encouraged by the results of the TAP study1 and a single case reported by Parodi,6 we performed PDT according to the TAP study protocol and achieved complete closure of choroidal neovascularization. Since the visual acuity was 6/9 and there was concern regarding the possibility of extension of the choroidal neovascular membrane into the foveal region, we performed PDT at closer intervals of 6 weeks rather than 12 weeks as per the TAP protocol. Our case illustrates that choroidal neovascularization secondary to a choroidal osteoma can be successfully treated with PDT.