Abstract
Abstract: :
Purpose: To assess visual function in variably advanced atrophic lesions and in boardering apparently healthy retinal tissue in patients with Sveinsson's chorioretinal atrophy as recorded by absolute threshold obtained with microperimetry. Methods: Static microperimetric data were obtained with a Rodenstock scanning laser ophthalmoscope (SLO) from both eyes of 3 patients with Sveinsson's chorioretinal atrophy, using the Scotometry (version 3.0) software provided with the instrument, to present stimuli and record responses. Two separate stimulus sizes were used, the Goldman I and II, presented on a background of 1 cd/m2. All stimuli were 0.2 sec in duration. Absolute thresholds were obtained by presenting stimuli between 0 dB to –25 dB in intensity to different areas of the retina, and the thresholds mapped out inside and outside lesions, and at the borders. Results: No visual function was found in tongue–like strips radiating from the optic disc, with near complete atrophy of the retina and the choroid. Absolute thresholds were elevated to between 0–15 dB in areas with less clear–cut lesions emanating from the disc and areas of the fundus with near complete atrophy. Border regions, just inside the lesion areas showed threshold elevation, while the threshold just outside the border areas was between 20–25 dB. Conclusions: These results show that sensitivity to light is reduced to variable extent in different areas. The photoreceptors do not seem to be functioning in the most advanced areas of disease. There is little function in the moderately affected areas and in some areas with no changes there appears to be moderate effect on the photoreceptors as indicated by threshold elevation.
Keywords: retinal degenerations: hereditary • perimetry • clinical research methodology