Abstract
Abstract: :
Purpose: The half width of macular pigment distribution (HWMPD) has been found to be increased with age. However, whether the MP profile patterns are also different with age, which are quantitatively analyzed in this study. Methods: Two-wavelength (460 nm/560nm) imaging fundus reflectometry was employed to estimate MP density distribution in 54 normal subjects who were divided into three groups (young, mid-age and old). The population and age were 24.8 +/- 2.6 (N=24), 40.2 +/- 8.3 (N=13) and 67.5 +/- 7.1 years (N=17) respectively. Van Norren and Tiemeijer's reflectance model was used to calculate the MP density distribution in the horizontal meridian of retina. Results: The average MP densities are 0.23 0.08, 0.22 0.06 and 0.23 0.06 OD for the young to old age groups. No statistical significant difference is found in the peak MP density between the groups (all p≷0.05). The average estimated HWMPD are 2.6 0.5, 3.1 0.5 and 4.1 0.6 degrees respectively, which have good agreement with our previous study. The MP profiles of the subjects are analyzed and can be generally categorized into three forms, which are convex, staircase and concave types of shoulder shape. It should be noted that the concave profile is not a shoulder, but for convenience we define it as a type of shoulder. Each group contains all types of profile shoulders, but in young group it has 18 concave (18/24 of total), in mid-age it has 8 staircase (8/13) and in old it has 5 convex (5/17) and 10 staircase shoulders (10/17). According to the results, could the staircase form of MP profile be a transitional stage in the progress of the MP accumulation in aging process? Since no sufficient data of a longitudinal study in the same subjects available to support this point, we would like to leave it as a question for further discussion or study. Conclusion: The finding of MP profile having different types of shoulders and which is possibly age related in this study has opened a door for the study of the causes of the MP accumulation.
Keywords: 462 macular pigment • 431 imaging/image analysis: non-clinical • 554 retina