Macular Pigment Concentration and Retinal Morphology

Abstract

Abstract: : Purpose: A population based cross–sectional study investigating putative risk factors for low macular pigment in older people in Northern Ireland Methods: A random sample of older adults aged 65 and above drawn from a general practitioners database were invited to participate in a study investigating risk factors for age–related macular degeneration. Participants completed a questionnaire on diet, lifestyle and medical history and underwent visual function assessments (logMAR distance acuity, contrast sensitivity and Lotmar interferometry). Macular carotenoid levels were measured using Resonance Raman spectroscopy. Lens status was graded during slit lamp biomicroscopy using LOCSII, dilated pupil size was measured and stereoscopic digitally acquired fundus images were graded using the WARMGS. The general linear model was used to explore the relationships between MP levels and risk factors. The model was run with average Raman counts as the dependent variable and other risk factors as independent variables with person effects included as a fixed factor taking into account the dependence between observations made on paired organs. On the basis of the results the model was rerun with the average Raman counts in the eye with the lower reading as the dependent variable and nuclear sclerosis grade as a fixed factor and all other risk factors as independent variables. Results: There were two hundred and four participants, 65–95yrs (mean=73.4yrs). The severity of nuclear sclerosis and dilated pupil size were chosen by the general linear model as having a significant association with the Raman reading (p=0.016 and p=0.002). The general linear model selected pupil size (p=0.01), age (p=0.007) and drusen size (p=0.004) as the variables that significantly influenced Raman counts. Two other variables, hyperpigmentation and smoking status approached significance and were in the anticipated direction (p=0.057 and p=0.104 respectively). The adjusted R squared for the final model was 0.402. Conclusions: After accounting for pupil size and lens status, features of early AMD such as pigmentary abnormalities and large drusen are associated with with lower macular carotenoid concentration.

Keywords: macular pigment • clinical (human) or epidemiologic studies: risk factor assessment • carotenoids/carotenoid binding proteins