Abstract
Purpose: :
We explore suitable optical and data processing possibilities of the Retcam® platform for the quantitative measurement of macular pigment (MP) in infant eyes. This will allow us to determine age-adjusted MP levels in a population of newborns, infants, and children.
Methods: :
Our method for the measurement of MP is based on the RetCam® platform, a video-based retinal imaging system widely used to inspect the infant retina. We have configured the instrument to permit reflection based imaging in a narrow spectral region overlapping the blue-green absorption range of the MP carotenoids. Two-dimensional pixel reflection intensity maps are obtained in which the MP is visible as a region of attenuated reflection. Using suitable software routines, we compare pixel reflection intensities from the peripheral retina and macular region, and in this way derive MP optical density levels as a quantitative measure for the MP concentration in the area of interest.
Results: :
A first-phase clinical trial involved 13 subjects aged 7 - 71 months. MP optical density levels ranged between 0.13 and 0.025. A plot of peak MP levels versus subject age reveals a highly correlated linear relationship (R2 = 0.77). In subsets of subjects with nearly identical age, significant differences in MP levels were observed. In all cases, the spatial MP distributions peaked in the center (fovea) and featured a roughly circular symmetry.
Conclusions: :
The RetCam® platform can be optimized for the quantitative rapid measurement of MP levels and their spatial distributions in the human infant retina. Individual levels and distributions can vary significantly, while on the average, infant MP levels increase with age up to an as yet undetermined limit. While MP distributions in adults can vary drastically in shape, including, e.g., ring-like distributions with absence of central MP, all infant distributions measured so far exhibit high central levels and circular symmetry. RetCam® based MP measurements will make it possible to study MP uptake kinetics as well as spatial MP modifications while the retina matures, and as a function of external factors such as dietary modifications and stress factors.
Keywords: macular pigment • imaging/image analysis: clinical • infant vision