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Terese Olsen, Trine Langaas, Peter J Bex, Stuart J Gilson, Rigmor Baraas; The effect of Omega-3 status on contrast sensitivity in healthy middle-aged Norwegians. Invest. Ophthalmol. Vis. Sci. 2014;55(13):765. doi: https://doi.org/.
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To investigate the relationship between contrast sensitivity and HS-Omega-3 Index in healthy middle-aged Norwegians.
Thirty-nine male and female subjects aged 43-50 years were included in the study. Subjects were healthy with no known ocular abnormalities. Subjects were corrected to best monocular logMAR letter acuity with natural pupils at 3 m, then given the appropriate near addition for 60 cm. Monocular letter contrast sensitivity function (CSF) was measured with the quick CSF method (Dorr, et al., IOVS, 2013;54:7266-7273) on a handheld device (iPad) at 60 cm. Sloan letters were digitally filtered with a log cosine with a peak frequency of 4 cycles per letter and one octave bandwidth. Different metrics were calculated: (1) the area under the log CSF (AULCSF), which provides a global contrast sensitivity measure, (2) CSF acuity, which defines the spatial frequency at which detection threshold was at 50%, (3) and sensitivity at six spatial frequencies (1, 1.5, 3, 16, 12 and 18.5 cpd). HS-Omega-3 fatty acid index was quantified by measuring the amount of 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.
Average AULCSF was 1.9 ±0.2 and average CSF acuity was 24.5 ±6.4. There was no difference between males and females. There was no correlation between AULCSF and age or HS-omega-3 index, CSF acuity and age or HS-omega-3 index. Average HS-Omega-3 index was 7.6±1.9 with no difference between males and females. There was a significant correlation between sensitivity at low spatial frequencies (1, 1.5 and 3 cpd) and HS-omega-3 index (Persons r = 0.4, 0.39, 0.37, p <0.002)
DHA is found in very high concentrations in the phospholipids of the photoreceptor outer segment disk membrane believed to be important for metabolic activity and visual function. The results demonstrate that the level of DHA affects visual function, especially contrast sensitivity at low spatial frequencies.
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