[Variability of visual acuity, dark adaptation and electroretinogram in retinitis pigmentosa].

Clinical and electrophysiological records are of particular importance in tapetoretinal degenerations. In the absence of therapy they are at least a help in establishing a differential diagnosis and a scale of progression of the disease; these in turn lead to improved counselling possibilities. In a retrospective study of 289 patients a great variability of ophthalmoscopic, functional and electrophysiologic findings was observed. The variability was seen both in individual examination of patients of all ages at one point in time, and in genetic pattern, penetrance and expressivity, Criteria for autosomal recessive inheritance were established in 21.3% and for simplex cases in 51.6%. Constriction the retinal vessels was the most reliable ophthalmoscopic finding, seen in 74% of the cases of RP. In 68% of the cases the onset of symptoms started before the age of 20. In 62% of RP patients the visual acuity remained 0.4 or better up to the sixth decade of life. In 40% of the cases the dark adaptation threshold was normal or raised only by up to 1.5 log units. The ERG was absent in 70%, residual in 10%, and subnormal in 20% of RP patients. The residual and subnormal ERGs showed predominantly rod involvement in 77%, equal rod and cone involvement in 17%, and chiefly cone involvement in 6% of 95 cases. The most common associated abnormalities were found to be cataract in 33% and myopia in 22%. (Detailed data on impairment of visual fields and on ERG analysis are published elsewhere: Gurewitsch, K., G. Niemeyer: Rod/cone separation by electroretinography, fundus changes and visual fields in retinitis pigmentosa. In: Techniques in Clinical Electrophysiology of Vision. G. Niemeyer and C. Huber (eds). Docum. Ophthal. Proc. Ser., in press).