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Brett G. Jeffrey, Lauren M. Renner, Martha Neuringer; Selective Loss of Central Retinal Function in Rhesus Monkeys Deficient in Xanthophylls and n-3 Fatty Acids. Invest. Ophthalmol. Vis. Sci. 2011;52(14):974.
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Retinal function as measured with the full field ERG (ffERG) is significantly altered in rhesus monkeys raised on diets lacking both n-3 fatty acids and xanthophylls. These animals also exhibit changes in central retinal structure including RPE remodeling, increased lipofuscin fluorescence and, in some n-3 deficient monkeys, geographic atrophy. We assessed whether central retinal function as recorded with the restricted field (40 deg) ERG (rfERG) was selectively affected in n-3 deficient/xanthophyll-free monkeys.
From birth to 15-20 years of age, 12 rhesus macaques were fed either a diet supplemented with the long-chain n-3 fatty acid DHA (DHA group; n=5) or an n-3 deficient diet (low n-3 group; n=7) known to reduce retinal DHA by 80%. Both diets lacked the xanthophylls lutein and zeaxanthin and therefore, none of the monkeys had macular pigment. Retinal function was assessed from ff- and rfERG measurement of A) The kinetics of dark adaptation from the recovery of rod-isolated ERG a-wave amplitude to a 4.4 log sc Td-s flash after a >99% bleach and B) Rod phototransduction assessed from the fit of a P3 model to rod-isolated ERG a-waves from 2.8-4.0 log sc Td-s flashes. Central retinal function relative to the full field was assessed from calculation of the rfERG/ffERG ratio for each parameter.
Within the central retina, the time constant of dark adaptation of low n-3 monkeys was 23% longer than for DHA monkeys (p<0.01). There was also a selective reduction in RmaxP3 from the central retina of low n-3 monkeys relative to the DHA animals (p<0.004). Full field rod sensitivity was reduced by 25% in low n-3 monkeys (p<0.06). For all monkeys combined, the time to reach 50% of full dark adaptation from the central retina was significantly longer relative to full field dark adaptation (p<0.001).
These results indicate a specific loss of central retinal function in monkeys with lifelong dietary deficiency of both n-3 fatty acids and xanthophylls, compared with those lacking xanthophylls alone. The most significant changes in low n-3 monkeys were a selective loss of central rods (rf:ff ratio) and slowing of central dark adaptation, which may relate to dysfunction of the retinoid cycle secondary to RPE remodeling in these animals. Central retinal dark adaptation was slowed relative to full field for all monkeys in this study; such a difference is not seen in normal monkeys and therefore, may be related to the lack of macular pigment in these animals. 1. Jeffrey B [IOVS 2010;51:ARVO E-Abstr 5567]
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