Night Blindness Due to Juvenile Pompe’s Disease (Type II Glycogenosis)

Abstract

Purpose: : To describe ophthalmological findings in a patient with late onset Pompe’s disease, a lysosomal storage disease, and to investigate whether this metabolic condition can be correlated with his night blindness.

Methods: : A twelve–year–old boy suffering from Pompe’s disease was referred for an ophthalmological evaluation because of a history of night blindness. The patient underwent complete ophthalmological work–up including orthoptic measurements, B–scan ultrasonography, visual field testing, electrophysiology and magnetic resonance imaging of the orbits.

Results: : The patient had a history of deteriorating night vision since age five. Exophoria and lack of convergence were noted. Visual acuity was 20/25 in both eyes. Anterior segments were normal. There was no blepharoptosis. Fundus examination revealed vitreous opacities and a diffuse dispersion of whitish material in the retina, more prominent in the mid periphery. Optic discs and maculae looked normal. Retinal vessels were of normal caliber but of increased tortuosity. Extraocular muscles were of normal shape and thickness. Ultrasonography revealed the vitreous opacities and some thickening of the mid periphery of the retina and choroid. Visual fields showed a relative scotoma corresponding to that thickening. The ERG responses showed significant deficits in scotopic function, while photopic function was much less compromised.

Conclusions: : Although accumulation of glycogen in retinal cells has been described in ultrastructural studies of retinas from patients with Pompe’s disease, this was not followed by visual impairment or fundoscopic abnormalities, as in our case. ERG findings of the presented case provide evidence for a generalized retinal degeneration. The deposition layers of the whitish material may represent storage of glycogen within retinal cells resulting in that degeneration, which clinically manifests as night blindness.

Keywords: metabolism • retina • electrophysiology: clinical