Abstract
Purpose:
To investigate the relationship between alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) level on measures of static and dynamic accommodation in healthy presbyopes.
Methods:
Thirty-nine healthy males and females aged 43-50 yrs, with no known ocular abnormalities, were included in the study. They were corrected to best monocular logMAR letter acuity with natural pupils at 3 m, and wore the correction with full aperture lenses in a trial frame during the test procedure. Dynamic accommodation was recorded using an eccentric infrared photorefractor (PowerRefractor II, PlusOptiX, Nürnberg, Germany). Participants were instructed to look at two targets, one at near (4D) and one at far (0.25D). Accommodative response was recorded continuously during the procedure. Participants were asked to change fixation (from distance to near, or near to distance) when a steady accommodative response was observed for 3 secs on the real-time output, twice at each distance. Variability in the accommodative response was defined as the standard deviation of that response across time. The percent composition of different fatty acids in whole blood was quantified by measuring the amount of ALA, EPA and DHA in whole blood (dried blood spot) with a test from OmegaQuant Health Diagnostic Laboratory Inc. (Sioux Falls, SD, USA). A drop of blood (finger prick) was collected on anti-oxidant treated filter. Results were analyzed and reported by the manufacturer.
Results:
Average ±SD amount of ALA, EPA and DHA were as follows: 0.35 ±0.23, 1.38 ±0.68 and 5.3 ±1.2. It was found that the dynamic accommodation response in general was more variable for near than for distance. The SD at near was 0.45 ±0.34 D and at far 0.34 ±0.18 D. There was no correlation between fatty-acid levels or dynamic accommodative stability and age. There was, however, a significant correlation between dynamic accommodative stability, at both near and far, and ALA level (Pearson r = 0.43-0.7, p<0.01).
Conclusions:
A higher ALA intake has been reported to have an effect on age-related change in lens nuclear density (Lu et al. JACN 2007:26:133-140). The results presented here demonstrate increased variability in dynamic accommodation with increasing ALA levels.
Keywords: 404 accommodation •
414 aging: visual performance •
618 nutritional factors