Macular function in severe disbinocular amblyopia

Abstract

Abstract Purpose: To evaluate the mechanisms of the visual function impairment in severe disbinocular amblyopia (SDA). Methods: 41 children with SDA 5‐17 years old; visual acuity 0,03‐0,1; parafoveal, paramacular, peripheric fixation were examined. Mixed, pattern, macular multifocal ERG examination (MBN Moscow and Roland Consult Germany) and topography, contrast, colour sensitivity and spatial contrast sensitivity were performed. Results: The impairment of the color sensitivity to unsaturated red, green and blue was found. The most changes were found for the green in of 7º from the macula. No changes in the mixed, macular and flicker 30 Hz ERG was found. Although some patients showed a supernormal a‐wave of the macular ERG as well as a subnormal b‐wave, supernormal flicker 30 Hz ERG and moderately subnormal pattern ERG. Mf ERG showed the decreased rates of retinal density in the 1st and 2nd ring with normal rates of N1 and P2 in all central hexagons. SDA with non‐central fixation in 2D display is manifested with the zone of maximal bioelectric activity noticeably shifted from the fixation point. Together with the stable central fixation there is a near‐to‐the‐norm retinal density in central rings as well as with the eccentricity, while the maximal bioelectric activity at the non‐central fixation coincides with the presumed projection. Conclusions: Changes in the color and contrast sensitivity and in the retinal bioelectric activityin SDA has a functional character. Rate of the found changes differs from those in other retinal and optic nerve pathologies and retrochiasmial changes in children. There might exist an abnormality of photoreceptor and neuronal interactions among other mechanisms of visual function impairment in ADA.