Abstract
Purpose :
Human studies have reported divergent results on age-related changes in macular pigment optical density (MPOD), and the relationship to lutein and zeaxanthin intake and other lifestyle factors has been difficult to determine. We quantified and characterized the spatial profile of macular pigment optical density (MPOD) across the lifespan in rhesus monkeys that all received the same life-long controlled diet.
Methods :
MPOD was estimated by two-wavelength reflectometry from rhesus monkeys (2-25yrs; n=44) fed a life-long standard laboratory diet. Peak MPOD was estimated from horizontal and vertical profiles through the fovea. MPOD volume was calculated in the superior, inferior, nasal, and temporal quadrants within the central 1 mm, and all quadrants were summed to determine MPOD total volume. Quantitative FAF images were also collected using the Heidelberg Spectralis with 488 nm excitation, and mean grey value (MGV) in was measured the same regions using ImageJ. MPOD and qFAF images were coregistered using I2K retina.
Results :
All 44 monkeys exhibited a central peak of MPOD, 29 of which showed secondary peaks approximately 0.3 mm from the center. Both peak MPOD and total volume decreased significantly with age (r=-0.50, r=-0.39 respectively). Total MPOD volume was also significantly lower in the superior quadrant than all other regions. Animals were stratified into those with high (n=11, above 0.035) or low (n=33, below 0.030) MPOD total volume with similar rates of decline with age in both groups. Nine of the high MPOD group exhibited a ring of reduced FAF at approximately 0.3 mm eccentricity, consistent with the location of the secondary MPOD peaks. In contrast, these rings were not detected in the FAF images of any of the low MPOD animals.
Conclusions :
Total MPOD decreased across the lifespan in rhesus monkeys fed a standard laboratory diet and a similar rate of decline was observed in animals with both high and low MPOD. These data make possible the comparison of in vivo measurements of MPOD and qFAF correlated with biochemical measurements and molecular mapping of lutein/zeaxanthin and sources of autofluorescence in retinal tissue. This data also will provide the foundation for examining the genetic and biochemical basis for differences in MPOD levels and spatial distribution in populations of nonhuman primates all fed the same controlled diet.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.