Macular pigment optical density
Macular pigment optical density is the concentration of pigment in the macula, the central region of the retina. Macular pigment absorbs short-wavelength blue light and may reduce oxidative stress in the retina through its antioxidant properties. Primarily two carotenoids, lutein and zeaxanthin, with smaller amounts of meso-zeaxanthin, these pigments come from foods like green leafy vegetables and yellow or orange fruits and are deposited in the macula lutea, a retinal area responsible for high-acuity vision. In research on visual function and ocular health, studies examine its association with conditions such as age-related macular degeneration and other retinal disorders.
Range
Macular pigment optical density ranges from 0 to 1 optical density unit, averaging 0.35 in the United States. The range is divided into three levels: low, mid-range, and high. Higher MPOD levels are associated with improved visual performance and a lower risk of age-related macular degeneration. Several factors, including diet, age, and overall eye health, contribute to variations in MPOD levels.
Measurement method
MPOD is calculated through the use of a Macular Pigment Densitometer to assess macular pigment optical density as a measure of retinal health. One unit is approximately equal to 0.025 ng macular pigment per mm² of retina. Heterochromatic flicker photometry is a noninvasive technique that uses flickering light stimuli to the retina, alternating between blue light at 465 nm and green light at 530 nm. Blue light absorption by the macular pigment results in reduced perceived flicker, which allows the determination of MPOD. Desktop-based devices, such as the MPS II, measure the retinal periphery and center in approximately 90 seconds per eye. Portable versions, such as the ZX Pro, are hand-held devices with patient-oriented software.
Statistics by nation
South Korea
A 2020 study of the Korean population measured macular pigment optical density with the Macular Pigment Screener II. The study found that healthy individuals had an average MPOD of 0.69 ± 0.18, and those with dry age-related macular degeneration had a lower average of 0.55 ± 0.17. Across all participants, the mean MPOD was 0.59 ± 0.20, with variations observed between different groups. The research also identified a statistically significant decline in MPOD with increasing age, indicating a gradual reduction over time.