Abstract
Purpose: :
To evaluate visual fields and localized retinal function in patients with unexplained visual loss.
Methods: :
Three young women with unexplained central visual disturbances, with a normal fundus appearance and in whom neurological examination including computer tomography (CT) and magnetic resonance imaging (MRI) demonstrated no abnormalities responsible for the visual loss, were further examined. They were given a thorough ophthalmological examination including Goldmann perimetry, fluorescein angiography, full-field electroretinography (full-field ERG), multifocal electroretinography (mfERG), multifocal visual evoked potential (mfVEP) and optical coherence tomography (OCT). A blood sample for molecular genetics was drawn from one patient.
Results: :
In all patients localized defects were verified with visual field assessment, but by ophthalmoscopy and fluorescein angiography fundus had a normal appearance. Full-field ERG demonstrated normal rod and cone amplitudes, but delayed implicit time in one of the patients. In all patients mfERG confirmed localized retinal dysfunction with reduced amplitudes, and a slightly prolonged implicit time within areas correlating to the visual field defects. In two of the patients the defects were basically asymmetrical and paracentral, and fulfilled the diagnostic criteria of acute zonal occult outer retinopathy (AZOOR). In the third patient the dysfunction was bilateral, mainly corresponding to the foveal area, and molecular genetics confirmed the diagnosis spinocerebellar ataxia type 7 (SCA7).
Conclusions: :
In patients with unexplained visual loss, a normal fundus appearance and normal neurological findings, further evaluation of retinal function with mfERG may be a valuable method for objective assessment of localized retinal disease, consequently improving our understanding of the pathogenesis.
Keywords: electroretinography: clinical • visual fields