Alcohol-consuming rhesus monkeys (Macaca mulatta) (mean consumption 2.6 g kg/day over a 5-year period) had greater a- and b-wave implicit times and lower b-wave amplitudes in their electroretinograms compared with those of the dietary control group at 2.5 and 5 years. The fatty acyl composition of brain specimens obtained by surgical biopsy at baseline, 2.5 years, and 5 years demonstrated that docosahexaenoic acid (DHA) had decreased in both groups of animals compared with baseline values. In the brains of the alcohol-treated animals, DHA was even further decreased (2.5 years: -20%; 5 years: -33%) compared with the diet controls. In the retinas of the alcohol-consuming animals at 5 years, there was a similar decrease in DHA (-35%) compared with controls. Generally, the n-6 fatty acid, docosapentaenoic acid (DPAn-6) was higher in these tissues, apparently compensating for the decreased DHA. A reciprocal change in the DHA/DPAn-6 ratio is associated with abnormal electroretinograms in a number of species. Thus, a marginal intake of n-3 fatty acids in some alcohol abusers may, in part, be responsible for the biochemical changes that underlie the diminished retinal function associated with the visual abnormalities observed in alcohol-amblyopic patients. Pawlosky RJ, Bacher J, Salem N Jr. Ethanol consumption alters electroretinograms and depletes neural tissues of docosahexaenoic acid in rhesus monkeys: nutritional consequences of a low n-3 fatty acid diet. Alcohol Clin Exp Res 2001 Dec;25(12):1758-65.

Electroretinographic amplitudes showed statistically significant losses in b- and a-waves after 6 and 16 weeks of dietary n-3 deficiency, respectively. The response amplitude to 30-Hz flicker was reduced 42% after 16 weeks. Retinal docosahexaenoic acid (DHA) levels of animals maintained on the safflower oil diet for 16 weeks were 42% of levels in age-matched control subjects. There were significant losses in maximum response amplitudes (R(mPIII) and R(mPII)), although the major effect was a reduction in sensitivity of the receptoral response. Complete functional recovery was observed only in animals repleted for 10 weeks. Weisinger HS, Vingrys AJ, Bui BV, Sinclair AJ Effects of dietary n-3 fatty acid deficiency and repletion in the guinea pig retina. Invest Ophthalmol Vis Sci 1999 Feb;40(2):327-38.

 Electroretinographic amplitudes in guinea pigs showed statistically significant 
losses in b- and a-waves after 6 and 16 weeks of dietary n-3 deficiency, respectively. The response amplitude to 30-Hz 
flicker was reduced 42% after 16 weeks. Retinal docosahexaenoic acid (DHA) levels of animals maintained on the 
safflower oil diet for 16 weeks were 42% of levels in age-matched control subjects. There were significant losses in 
maximum response amplitudes (R(mPIII) and R(mPII)), although the major effect was a reduction in sensitivity of the 
receptoral response. Complete functional recovery was observed only in animals repleted for 10 weeks. Functional 
deficits in receptoral and postreceptoral subcomponents (PIII and PII) of the electroretinogram showed a correlation 
with age and retinal DHA level. Weisinger HS, Vingrys AJ, Bui BV, Sinclair AJ. Effects of dietary n-3 fatty acid deficiency and repletion in the guinea 
pig retina. Invest Ophthalmol Vis Sci 1999 Feb; 40(2): 327-338. 

A conversion factor (x1.35) should be applied to data collected with bipolar corneal electrodes to estimate the amplitudes of the modelled parameters accurately. The corneal electrode gave a precision of 39 microV which yields a statistical power of 0.90 for a sample size of 7 subjects. We conclude that bipolar corneal electrodes provide smaller electroretinogram amplitudes due to their location and reduced span of the retinal generators. Bui BV, Weisinger HS, Sinclair AJ, Vingrys AJ. Comparison of guinea pig electroretinograms measured with bipolar corneal and unipolar intravitreal electrodes. Doc Ophthalmol 1998;95(1):15-34

Guinea pigs born of dams supplied with eicosapentaenoic, docosapentaenoic, and docosahexaenoic acids n-3 fatty acids in the commercial pellets (experiment 2) showed higher levels of retinal docosahexaenoic acid at weaning compared with those born to dams fed chow containing only alpha-linolenic acid (experiment 1). Depletion of retinal docosahexaenoic acid after weaning fitted a two-stage exponential decay, with the rate of depletion in the group with the lower retinal docosahexaenoic acid at weaning more than double the rate of depletion in the group with the higher docosahexaenoic acid. At 16 weeks post-weaning, retinal docosahexaenoic acid for the lower group was approximately half that of the group from dams fed long chain n-3 fatty acids. An adequately supplied mother seems capable of providing an infant with enough n-3 fatty acids to withstand a longer period of dietary deprivation imposed after weaning. Weisinger HS, Vingrys AJ, Abedin L, Sinclair AJ. Effect of diet on the rate of depletion of n-3 fatty acids in the retina of the guinea pig. J Lipid Res 1998 Jun;39(6):1274-9

Guinea pigs were raised through three generations on semipurified diets, containing different amounts of n-3 fatty acids, using a supplementary oil as the sole source of lipid. Comprehensive electroretinographic assessment showed significant reductions (p < 0.003) in both peak-to-peak and a-waves of safflower oil fed animals. Phospholipid fatty acid analysis revealed significant DHA deficiency (retinal DHA 2.5% vs. DHA 21.0%; p < 0.001) in guinea pigs reared on the safflower oil (n-6/n-3 = 72) as compared with those with canola oil (n-6/n-3 = 2.5). Weisinger HS, Vingrys AJ, Sinclair AJ. Effect of dietary n-3 deficiency on the electroretinogram in the guinea pig. Ann Nutr Metab 1996;40(2):91-98

Retinal phospholipids of guinea pigs varied between 2.5 and 30.8% DHA, and visual function was assessed by full-field flash electroretinography over a range of exposure levels spanning six log units. Retinal function was a second-order polynomial "inverted U-shaped" function of tissue DHA level. Although some DHA is essential for normal retinal function, increases in the DHA level past an optimal amount, 19%, provided diminishing returns. Weisinger HS, Vingrys AJ, Sinclair AJ. The effect of docosahexaenoic acid on the electroretinogram of the guinea pig. Lipids 1996 Jan;31(1):65-70

Fatty acid analyses of the retinal phospholipids of the four-week-old guinea pigs revealed that the group fed DHA (from the fish oil) had the highest level of DHA (32%), compared with values of 19 and 13% for the groups fed canola oil diet and commercial diet, respectively, and 2% for the group fed the diet deficient in n-3 PUFA. Weisinger HS, Vingrys AJ, Sinclair AJ. Dietary manipulation of long-chain polyunsaturated fatty acids in the retina and brain of guinea pigs. Lipids 1995 May;30(5):471-3

The percentage intake of breast milk correlated with levels of docosahexaenoic acid (DHA) in plasma (r = 0.818, P &lt; 0.0001) and red cells (r = 0.534, P = 0.035), and significant differences in fatty acid profiles were seen between infants receiving &gt; 50% and &lt; 50% breast milk. No difference was seen in retinal sensitivity between infants receiving &gt; 50% or &lt; 50% breast milk. A positive correlation was seen between scotopic (rod) b-wave implicit time on ERG and DHA in both plasma (r = 0.733, P = 0.001) and red cells (r = 0.502, P = 0.04). These data did not support the hypothesis that increased dietary DHA results in enhanced retinal maturation. Visual acuity measured at 40 weeks PCA and again 3 months later was similar between groups, and all infants seemed within age-appropriate normal ranges at expected date of delivery and at 3 months corrected age. Leaf A, Gosbell A, McKenzie L, Sinclair A, Favilla I. Long chain polyunsaturated fatty acids and visual function in preterm infants. Early Hum Dev 1996 Jul 5;45(1-2):35-53.