Zdravniški Vestnik (Dec 2002)
ELECTROOCULOGRAPHY AND PATTERN ERG IN THE DIAGNOSTICS OF BEST’S VITELLIFORM DISTROPHY
Abstract
Background. The aim of the study was to develop electrooculography in accordance with ISCEV standards and to test its accuracy in the diagnosis of Best’s disease, where the EOG results should be invariably abnormal in all affected members. The pathophysiology of Best’s disease is not yet completely understood, so pattern and full field flash ERG responses compared to visual acuity and stage of the disease were used to asses the neurosensory retinal function in different stages of Best’s disease.Patients and methods. The EOG was recorded in accordance with ISCEV standards on 30 healthy individuals to determine normal values of our laboratory. Pattern as well as photopic and scotopic ERG were recorded on 24 eyes of 12 patients with typical Best’s disease with abnormal EOG responses. The results were compared to visual acuity and stage of the disease.Results. Our EOG normative data are comparable with results from other laboratories: the mean value of Arden ratio is 2.32, the range of 2 standard deviations from the mean value is from 1.6 to 3.04. The patients with Best’s disease have statisticaly significant lower values of Arden ratio (the mean value beeing 1.19). 12 patients (24 eyes) with Best’s disease with abnormal EOG values were divided in two groups according to visual acuity. In the first group of 12 eyes with visual acuity > 0.5 PERG P50 and N95 responses were all in the normal range. In the second group of 12 eyes with visual acuity 0.5 or less PERG showed reduced both P50 and N95 responses in 5 eyes, and N95 solely, in two eyes.The photopic and scotopic electroretinographic responses were normal in all patients. Progression of the disease, seen in the deterioration of visual acuity, corresponded well with reduction of both PERG P50 and N95 responses. There was no correlation found between visual acuity and EOG responses.Conclusions. In the study on patients with Best’s disease, it was confirmed that EOG is a very sensitive test for detecting the disease. On the basis of EOG results alone no assumption can be made about the stage of the disease, as EOG is abnormal in all the patients, regardless of the stage of the disease. Pattern ERG is getting abnormal with progression of the disease, indicating relative preservation of neurosensory retina in initial stages of the disease, giving opportunity for electrophysiological determination of the progression of the disease.
