Grating visual acuity using the preferential-looking method in elderly nursing home residents

PURPOSE. To assess the performance of two approaches to visual acuity testing in a group of nursing home residents with cognitive impairment. The study was a cross-sectional comparison of the effectiveness of two tests of visual acuity. METHODS. Nursing home residents participating in a clinical trial were tested with both recognition acuity charts and grating acuity cards (Teller) by masked observers. RESULTS. Of the nursing home residents (n = 656) who participated in the study, 86% could respond to visual acuity testing in at least one eye. Eighty-four percent were testable using Teller cards versus 73% who were testable by Early-Treatment Diabetic Retinopathy Study (ETDRS) charts or Lea symbol charts. Forty-one percent of individuals with MiniMental Status Examination (MMSE) scores lower than 10 were testable by recognition acuity, whereas 61% were testable with grating acuity cards. Grating acuity correlated well with recognition acuity (R = 0.79; 95% CI, 0.75-0.98, intraclass correlation coefficient [ICC]). The correlation was slightly lower in individuals with decreased MMSE scores. Although grating acuity was one line better than recognition acuity on average and median acuities were the same, 24% of individuals had results that differed by three or more lines. CONCLUSIONS. Teller acuity cards can effectively test the vision in cognitively impaired individuals who are not testable by conventional means. Grating acuity results correlated well with those of recognition acuity, although differences of three or more lines were not uncommon. Wider use of grating acuity testing allows a more complete assessment of visual function in the cognitively impaired elderly.