Phosphoglycerate kinase (PGK) deficiency is an X-linked neurometabolic genetic disorder with variable systemic manifestations. So far, only one patient with retinal anomalies has been reported, but no visual electrophysiology findings were described. We report the first description of visual electrophysiology in a child with PGK deficiency. This provides further information for the site of involvement in the eye.
Tunnel vision is a classic sign among patients with advanced glaucoma. However, other conditions such as retinitis pigmentosa, optic neuritis and rod-cone dystrophy may be characterized by similar visual field defects. A 52-year-old lady with a family history of glaucoma presented with bilateral gradual loss of peripheral vision for two years. She claimed to have poor night vision about 20 years prior to this presentation. Her visual acuity was 6/7.5 in both eyes. The anterior chamber depth was moderate bilaterally, with Schaffer grading on gonioscopy of grade I to II. The intraocular pressure was 14 mmHg in both eyes. The optic discs appeared normal. Fundus examination showed scattered hypopigmented changes sparing the fovea. Humphrey visual field test revealed bilateral constricted visual fields. She was diagnosed with retinitis punctata albescens (RPA) based on her symptom of poor night vision, supported by the diffuse hypopigmented changes in her fundi. The management of this condition involves careful counselling regarding the genetic nature of the disease and its progressive course. We discuss this case to illustrate the importance of a thorough history taking and careful fundus examination in the workup of patients presenting with tunnel vision.