Abstract
Purpose::
We report the ophthalmologic findings of two sisters with moderate glutathione synthetase deficiency, an autosomal recessive inborn error of metabolism resulting in very low intracellular levels of the free radical scavenger glutathione. In the neonatal period, treatment with acidosis correction was started. Supplementation with vitamin E (10 mg/kg/d) was started before puberty and with vitamin C (100 mg/kg/d) in their twenties.
Methods::
The patients were investigated with clinical ophthalmological examination and the visual acuity was tested by the Early Treatment Diabetic Retinopathy Study (ETDRS) chart. Visual field (VF) examinations were performed with a Goldmann perimeter. A Goldmann-Weekers' adaptometer was used to determine the visual sensory threshold after standard preadaptation. The course of dark adaptation was followed for 45 min. Color vision was tested and full-field electrophysiological tests, single flash, and flicker ERGs as well as evoked potentials (VEPs) were recorded according to the recommendations of ISCEV (International Society for Clinical Electrophysiology of Vision).
Results::
The most prominent finding was progressive retinal dystrophy with hyperpigmentations and maculopathy. Generally disturbed functioning of both the outer and inner layers of the retina resulted in attenuated or nearly abolished electroretinograms. These findings agree with a rod/cone type of retinal dystrophy, and we suggest that this is due to glutathione deficiency. Treatment with antioxidants such as vitamins E and C seems to prevent the progression of CNS damage. We speculate it might also prevent retinal dystrophy in patients with glutathione synthetase deficiency.
Conclusions::
We suggest that patients with retinal dystrophy and additional neurological signs should be investigated for a defect in glutathione metabolism. Also, we recommend that patients with low levels of glutathione should be examined for retinal dystrophy. Our results suggest that a decreased capacity for scavenging reactive oxygen species and/or increased oxidative stress may cause retinal dystrophy. If this is the case, the redox state in the retina should be a potentially useful therapeutic target to prevent reduced visual function and blindness.
Keywords: oxidation/oxidative or free radical damage • degenerations/dystrophies • apoptosis/cell death