Visual Function Versus Visual Acuity in Older People

Purpose: To determine visual function (VF) status in older people, to establish its degree of correlation with visual acuity (VA), and to assess its association with other physical and mental functional limitations. Participants: A sample of 1,160 persons aged 65 years or over were selected by simple randomization. Methods: The participants' VF (The Visual Function Index - VF-14), VA, self-reported vision, mental and physical function (Katz Index, Pfeiffer's test, and Geriatric Depression Scale), and socio-demographic data were determined. Multiple linear regression was used to assess the association between VF and its conditioning factors. Statistical adjustment was made for the possible confounding variables. Results: Of the studied subjects, 6.3% (95% confidence interval (CI) = 4.93-7.82) had VA of less than 6/18 in the better eye and 20.9% (95% CI = 18.6-23.3) had VA of less than 6/12. The best corrected VA of each participant demonstrated moderate correlation with his or her VF-14 score (r = 0.416; p<0.001). Using multiple regression analysis, the variables associated with VF status were: visual impairment, self-reported poor vision, dependence in daily activities, cognitive impairment, depressive symptoms, female gender and older age. These independent variables explain 34.4% (r(2) = 0.344) of the variation in the data. Conclusions: VF impairment is common in older persons and when associated with other limitations, it may be considered a major health problem with important consequences. As a complement to the preventive care guidelines on VA in older persons, assessment of VF impairment in clinical practice, using appropriate visual screening tools, is advisable.