Screening for ophthalmic disease in older subjects using visual acuity andcontrast sensitivity

Objective: Despite early interest in contrast sensitivity as a screening te st for ophthalmic disease, most published opinion suggests that there is no benefit over conventional measurement of visual acuity. Taking a primary c are perspective of screening, the authors evaluated the ability to discrimi nate those with any diagnosed ophthalmic disease in a large sample represen tative of the general population. Design: Retrospective analysis of a clinical, cross-sectional survey. Snell en visual acuity, contrast sensitivity (Arden plates, American Optical cont rast sensitivity test), and ophthalmic diagnosis were reported previously, Participants: A sample of 3283 subjects, all aged at least 50 years, were s elected randomly from residents of a health district in Sydney, Australia. Ophthalmologic diagnosis (ophthalmic disease presence/absence) had been con firmed for 2522 of these subjects. Main Outcome Measures: Signal detection techniques (the receiver-operating characteristics function [ROC], quality ROC [QROC], and weighted kappa coef ficient of association [kappa(r)]) were used to evaluate test discriminabil ity. Results: Because analyses of right and left eyes were almost identical, onl y right eye results are presented. Advantages of kappa(r) over ROC were sho wn. Discrimination of those with diagnosed ophthalmic disease from those wi thout ophthalmic disease was best with Arden plate 7 (kappa(0.5) = 0.93) an d was better than distance Snellen visual acuity (kappa(0.5) = 0.59) Arden plate 7 (6.4 cyc/deg) correctly assigned 96% of subjects at its optimal pas s-fail criterion. Conclusions: in the primary care setting, a person older than 50 years of a ge with reduced contrast sensitivity, as determined by Arden plate 7, requi res extra care in subsequent examinations because this person is likely to have an ophthalmic disease.