International Ophthalmology 22: 307–312, 1998. © 2000 Kluwer Academic Publishers. Printed in the Netherlands. 307 Patient perceptions of quality-of-life associated with bilateral visual loss Gary C. Brown 1 , Melissa M. Brown 2 , Sanjay Sharma 3 & Heidi C. Brown 1 1 Retina Vascular Unit, 2 Cataract and Primary Eye Care Service, Wills Eye Hospital, Philadelphia PA, USA; 3 Retina Service and Department of Epidemiology Health Policy Research Unit, Queens University, Kingston, Ontario, Canada Accepted 30 December 1999 Key words: utility analysis, bilateral visual loss Abstract 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. Utility theory was developed in the 1940’s to allow quantification of uncertainty [1]. By the 1970’s, re- searchers began to apply utility theory to health care [2]. Utility analysis allows an objective evaluation of the quality-of-life associated with a health (disease) state [3–5]. By convention, a utility value of 1.0 correlates with a perfect health state, while a utility value of 0.0 cor- relates with death [3–5]. The higher the utility value, the better the quality-of-life. As examples, mild angina has been associated with a utility value of 0.90, while severe angina has been associated with a utility value of 0.50 [5]. It has been shown that utility values in ophthalmo- logy decrease in direct proportion to the level of visual loss, particularly with the level of visual loss in the better seeing eye [6, 7]. It has also been demonstrated that the utility estimates of ophthalmologists for spe- cific levels of bilateral visual loss are vastly different than those of patients who have experienced the visual loss firsthand [8]. Other publications have shown as well that the perceptions of patients and physicians can dramatically differ in regard to the disability induced by a disease entity [9–11]. The authors herein undertook a study of patients with vastly different levels of vision in each eye using utility analysis. Each patient was asked to assume that the vision in his or her better eye was the same as the vision as in the poorer eye, and was then evaluated using the time tradeoff method of utility measurement. These estimates of utility values were compared to those of patients who had visual loss in both eyes to the same degree that the study patients had in the worst eye. The intent was to ascertain whether patients with unilateral visual loss can accurately estimate the degree of impairment in performing the activities of