Eight–Year Changes in Acuity and Contrast Sensitivity in an Elderly Population: SEE Study

Abstract

Abstract: : Purpose: To describe changes in acuity and contrast sensitivity over eight years of follow up in the Salisbury Eye Evaluation (SEE) study. Methods:: 2520 participants, aged 65 to 84 from the original SEE study were recalled for three subsequent visits with an average follow up of eight years. Best corrected visual acuity (VA) was measured separately for each eye with an ETDRS chart. Contrast sensitivity (CS) was measured with the Pelli–Robson chart. We estimated both the average change in visual function for an eye over time and the extent of variation in personsâ|*128*|^TM rates of visual decline, using a linear model with random effects for the study participants and their vision slopes over time. Models included â|*128*|œfixedâ|*128*||*157*| effects that estimated an average trajectory for the cohort and accommodated correlations between eyes and across visits within subjects. All models were adjusted for demographic factors, cognitive status, and incident cataract surgery. Results: Four rounds of data were available for 1080 participants and three rounds of data were available for 1243 participants. The main reason for loss to follow up was death. Results for average decline in the cohort follow: In eyes with good VA at baseline (20/40 or better) visual acuity declined by 0.4 letter per year of follow up. Eyes with good CS at baseline (1.3 log CS or better) lost 0.2 letter per year of follow up. The rate of decline in the worse–seeing eye was twice as fast for VA and CS than in the better–seeing eye. There was appreciable variability in personsâ|*128*|^TM rates of vision change: we estimated a 1.5–letter standard deviation of VA change rates and a .7–letter standard deviation of CS change rates. The pattern of results was confirmed in the larger cohort of participants with three rounds of data. Conclusions: On average, there is a modest decline in VA and CS among elderly participants over an eight–year period. For those with good vision at baseline, the loss is less than 1 line for VA or 2 letters for CS. However, the variability in personsâ|*128*|^TM rate of vision change means that some individuals will lose 3 or more lines of VA and 6 or more letters of CS over 8 years. In the absence of incident eye disease, the majority of those with good acuity and contrast sensitivity in their seventh or eighth decades can expect to retain good visual function for at least another 8 years.

Keywords: aging: visual performance • contrast sensitivity • visual acuity