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ABSTRACT
A 42-year-old man with Hunter syndrome developed bilateral visual field loss. Visual field testing demonstrated bilateral ring scotomata that corresponded to areas of thinning seen on standard resolution optical coherence tomography. High-speed, ultrahigh resolution optical coherence tomography, capable of 3.5-micron axial resolution, showed a loss of photoreceptors outside the fovea and cystoid spaces within the inner nuclear, ganglion cell, and outer nuclear layers. These results were consistent with histopathologic features that have been reported previously in patients with Hunter syndrome. Optical coherence tomography could be used as a diagnostic modality to monitor patients with Hunter syndrome and to detect subclinical forms of disease. [Ophthalmic Surg Lasers Imaging 2007;38:423-428.]
INTRODUCTION
The lysosomal storage disease, Hunter syndrome or mucopolysaccharidosis type II, results from the X-linked inherited deficiency of the enzyme iduronate 2-sulfatase. Progressive dermatan sulfate and heparan sulfate accumulation in all tissues of the body leads to multiple systemic problems, including cardiac abnormalities, hepatosplenomegaly, and progressive deafness.
Ocular manifestations of Hunter syndrome include exophthalmos, hypertelorism, and pigmentary retinopathy. Unlike other lysosomal storage diseases, patients with Hunter syndrome typically exhibit clear corneas. Histopathologic and electron microscopic reports show retinal abnormalities similar to retinitis pigmentosa, including the loss of photoreceptors peripherally and the migration of retinal pigment epithelial pigment into the retinal layers.1
The following case is an example of Hunter syndrome imaged with high-speed, ultrahigh resolution optical coherence tomography (OCT), which is capable of 3.5-micron axial resolution in the human eye2 in comparison to 8- to 10-micron axial resolution of Stratus OCT (Carl Zeiss Méditée, Dublin, CA).3
CASE REPORT
A 42-year-old man with Hunter syndrome was referred to our institution for evaluation of bilateral visual field loss. During the past few years, he had noticed difficulty seeing pedestrians while driving. On ophthalmic examination, his visual acuity was 20/30 in the right eye and 20/25 in the left eye. His corneas were clear bilaterally. Fundus examination showed normal-appearing retinas with no pigmentary changes. Both optic nerve heads were slightly crowded (Figs. IA and IB). Visual field testing (30-2 full-threshold test with the Humphrey Visual Field Analyzer [Carl Zeiss Méditée]) showed bilateral ring scotomata (Figs. IC and ID). Hertel exophthalmometry was 23 mm on the right and 2 1 mm on the left. Fluorescein angiography revealed choroidal...