Patient perceptions of quality-of-life associated with bilateral visual loss

Purpose: To ascertain whether patients with unilateral visual loss to a specific level are able to approximate the degree of impairment of quality-of-life experienced by patients with bilateral visual loss to the same level. Methods: One hundred thirty-three study group patients with (1) visual loss to 20/40 or worse in at least one eye, and (2) a marked difference between the visual acuities in their two eyes, were polled using the time tradeoff method of utility value measurement. All patients were asked to assume that the visual acuity in both of their eyes was as poor as the visual acuity in their worst seeing eye. These utility values were then compared to those obtained from a control group of 173 patients with known utility values who had similar bilateral visual loss. Both the study and control groups were stratified into 4 levels of visual loss (20/40 to 20/50, 20/60 to 20/100, 20/200 to 20/400, and counting fingers to light perception). Results: Mean utility values for the study group ranged from 0.47 to 0.71. Patients with unilateral visual loss, given the assumption of bilateral visual loss to the same degree, routinely demonstrated no significant difference in utility preferences as compared to patients with true bilateral visual loss to the same level. Conclusions: Patients with unilateral visual loss can very accurately estimate the degree of impairment of quality-of-life that would result if visual loss to a similar degree occurred in the remaining eye with better vision.