Abstract
Purpose:
To determine the 5-year incidence of loss of accommodative ability in a large cohort of adults.
Methods:
Subjects (n=2256, age 21-84 years at baseline) participated in both the baseline (2005-2008) and 5-yr follow-up exam (2010 -2012) of Beaver Dam Offspring Study. At each visit a Grand Seiko Autorefractor was used to obtain three measures of refractive error; distance correction and with correction focusing on two near targets; one requiring 2 diopters (D) and the other 4.5D. Readings were converted to spherical equivalent (sphere + ½ cylinder) (SE). Participants were classified as myopic (SE ≤ -1.00), hyperopic (SE ≥ +1.00) or emmetropic (SE > -1.00 and < +1.00). At each of the two near targets, the participant was considered to have lost accommodative ability if the spherical equivalent was ≥ -0.50. Subjects with cataract surgery were excluded.
Results:
In preliminary analyses of right eyes, there were 741 participants in the baseline exam who were able to accommodate at both targets. Of those, 333 (45%) were not accommodating at the 2D target and 241 (33%) were not accommodating at the 4.5D target at the 5-yr follow-up exam. Age was highly associated with the incidence of loss of accommodative ability (mean age of accommodating at 2D = 38.2 years; 4.5D = 38.7 years, not accommodating at 2D = 44.7 years; 4.5D = 46.1 years) and risk of losing accommodative ability increased with increasing age (OR 3.18, 95% CI 2.59-3.90 for each 5 years of age). Participants with hyperopia were less likely to lose accommodative ability (OR 0.01, 95% CI 0.00 - 0.04) compared to those with emmetropia. There was no association between myopia or sex with loss of accommodative ability. Eight participants over the age of 55 years at the baseline examination had accommodative ability at both distances at both examinations.
Conclusions:
Loss of accommodative ability is very common in middle-age. These data show that adjusting for age, hyperopia was associated with decreased risk. In spite of the strong age effect, a small number of people retain accommodative ability beyond mid-life. Further investigation is necessary to identify factors that are associated with retention of accommodative ability. To the best of our knowledge, this is the first longitudinal study using an objective measure to investigate the loss of accommodative ability.
Keywords: 404 accommodation •
413 aging