Abstract
Abstract: :
Purpose: To quantify the effect of age and the influence of diabetes on the detection of microdot stimuli. Methods: The Rarebit Microdot Fovea Test (RMFT) relies on the perception of very small (<0.5 MAR) bright stimuli, called microdots. The RMFT tests the integrity of the receptor matrix within the 3–degree visual field and the results are expressed as % hit rate, i.e. the fraction perceived of the presented microdots. Thirty–five healthy subjects were tested with five different stimulus luminance levels, 158, 64, 53, 41, and 33 cd/m2 respectively. The effect of age was evaluated on each luminance level. In addition, ten otherwise healthy diabetic subjects, with disease duration of at least 5 years and subjectively normal vision were examined with best corrected visual acuity, using the ETDRS method, RMFT and fundus photography. Results: Significantly correlation between age and RMFT mean hit rate was observed at stimulus luminances of 64 cd/m2 or less (r = 0.4, p = 0.02). The diabetic patients had significantly lower RMFT mean hit rate at all tested luminance levels (p < 0.004) compared to age–corrected normal values, albeit visual acuity was normal (>= 20/20) and no macular–near changes were detected by fundus photography in the retina. Conclusions: The preliminary results indicate that microdots can identdify the effect of age on the visual system, provided that the stimulus luminance is carefully selected.The Rarebit Microdot Fovea Test may be able to detect sub clinical changes in foveal function in patients with diabetes
Keywords: macula/fovea • diabetes • perception