Stereopsis in end-stage renal disease (ESRD)

We investigated an effect of end-stage renal disease (ESRD) on the visual system by measuring the ability of 21 patients to perceive depth in the random dot stereograms and circles of the Randot Test. To control for other factors which might influence performance on the tests of stereopsis, patients were compared with healthy controls matched for age, years of education, IQ, and general cognitive ability. Vernier acuity (thought to reflect mainly central processing) and Landolt acuity (more sensitive to retinal and optical abnormalities) were also measured, but the study did not include a formal ophthalmological examination. All controls could perceive depth in random dot stereograms, whereas 9/21 patients could not. Patients who could perceive depth had worse stereoacuity than did their matched controls. The patient group as a whole had worse Vernier and Landolt acuities than the controls. The stereoblind patient subgroup had similar Vernier acuity to the stereoscopic subgroup, but worse Landolt acuity, and was more likely to have peripheral vascular disease. We conclude that ESRD had affected structures both within the eye, and within the visual brain. However, the similarity of Vernier acuity and difference of Landolt acuity in the stereoblind and stereoscopic patient subgroups suggest that the differences in stereoscopic ability arise from abnormalities in the eyes rather than in the brain.