A case of chorioretinal atrophy due to sclerochoroidal calcification

Abstract

Editor, Ectopic scleral and choroidal calcification, a rare pathology, can be classified as dystrophic or metastatic (Honavar et al. 2001). The former is associated with senile degeneration, chronic inflammation or trauma and the latter with systemic abnormal calcium–phosphorus metabolism including hyperparathyroidism, pseudohypoparathyroidism, sarcoidosis, hypervitaminosis D and chronic renal failure (Shields & Shields 2002). We report a case with bilateral chorioretinal atrophy secondary to metastatic sclerochoroidal calcification in a patient with chronic renal failure and hyperparathyroidism. A recent advance in computed tomography (CT), that is three-dimensional (3D) orbital reconstruction from thin CT slices, helped establish the diagnosis. A 57-year-old Japanese woman was referred to our department for the evaluation of bilateral eye wall calcifications identified on routine head CT before kidney transplantation. She had a 17-year history of haemodialysis because of chronic renal failure. Blood tests showed elevated levels of parathyroid hormone (74.5 pg/ml) and phosphate (4.6 mg/dl) and borderline serum calcium depletion (8.7 mg/dl); the hyperparathyroidism was secondary to end-stage renal disease. Her best-corrected visual acuity was 1.2 bilaterally, and the intraocular pressure measured by applanation tonometry was 14 mmHg bilaterally. A relative afferent pupillary defect was plus/minus in the left eye. Funduscopy showed a vertical cup-to-disc ratio of 0.5 bilaterally; the inferior rim of the right disc was slightly pale, as was the entire rim of the left disc. Chorioretinal atrophy was present in the mid-peripheral fundus bilaterally (Fig. 1A, 1B). Visual field testing by Goldman perimetry showed a virtually normal right eye (Fig. 1C) and a relative scotoma in the left eye (Fig. 1D). Ultrasound sonography showed dense echogenic areas with acoustic shadowing at the ocular walls bilaterally (not shown). The 3D orbital images reconstructed from thin-sliced (0.67-mm step) axial CT (Brilliance CT 64-Channel, Philips Electronics, Eindhoven, the Netherlands) showed ectopic calcifications around both optic nerves (Fig. 1E, Video clip S1); the extent of the calcification coincided exactly with that of the chorioretinal atrophy bilaterally. The patient was diagnosed with hyperparathyroidism-related metastatic sclerochoroidal calcifications and related chorioretinal atrophy bilaterally. Areas of chorioretinal atrophy (dotted lines) are seen in the mid-peripheral fundus of the right (A) and the left (B) eyes. The visual field in the right eye (C) is normal; the left eye (D) has a relative scotoma. The 3D CT orbital image shows ectopic sclerochoroidal calcification bilaterally (E); the spatial distribution of the calcification matches the chorioretinal atrophy (A, B). Although visual disturbances caused by sclerochoroidal calcification have been reported in cases with posterior segment involvement (Zaman & Spalton 1995) and choroidal neovascularization (Cohen et al. 1998), most sclerochoroidal calcifications are asymptomatic and found incidentally. Sclerochoroidal calcification classically manifests as multiple discrete white or yellow fundus lesions (Honavar et al. 2001); the current patient had only diffuse chorioretinal atrophy, a relative scotoma and subtle changes in the optic nerve heads that were presumably related to antegrade degeneration from the chorioretinal atrophy. Thus, if we did not have her medical history, the chorioretinal atrophy easily could have been interpreted as simple ageing changes or changes owing to unknown aetiology. Zaheen et al. (2000) previously published orbital 3D images of one case of idiopathic sclerochoroidal calcification; however, to our best knowledge, the current case is the first to clearly show the spatial relationships between the extent of the chorioretinal atrophy and ectopic calcification formation. When ophthalmologists observe chorioretinal atrophy, obtaining a medical history of systemic diseases that could alter calcium and phosphorus metabolism is important; if a patient has such a systemic disease, sclerochoroidal calcification must be included in the differential diagnosis. Three-dimensional orbital imaging is useful for recognizing the association between the calcification and the fundus lesions. Video Clip S1. The orbital 3D CT images. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer-reviewed and may be re-organized for online delivery, but are not copy-edited. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.