Macular pigment optical density in a Southwestern sample.

Purpose: Increasing evidence implicates macular pigment in protecting the retina and retinal pigment epithelium from light-initiated oxidative damage. Little information, however, is available regarding "average" levels of macular pigment in the general population. This study was designed to assess macular pigment in a high-light environment and to determine what personal characteristics influence macular pigment density in that sample.

Methods: Macular pigment optical density was measured psychophysically using a 1 degree, 460-nm test stimulus. Personal data were collected using a questionnaire.

Results: 217 subjects (79 men, 138 women) were recruited from the Phoenix metropolitan area (age range = 17-92 years). The average macular pigment density was 0.22 +/- 0.13. There was a slight tendency for macular pigment density in this sample to decline with age (r = -0.14, P < 0.02). Average macular pigment density was significantly lower in women versus men (P < 0.05), lower in individuals with light-colored irises versus dark-colored irises (P < 0.009), and lower in heavy smokers compared to light (P < 0.0045) and never (P < 0.034) smokers.

Conclusions: Macular pigment density was lower than average levels obtained from the Northeast but similar to average values obtained in a recent study of adults recruited from Indianapolis. Consistent with past studies, MP density was 13% lower in women and 18% lower in individuals with light- versus dark-colored irises. The relation of smoking to macular pigment density was only significant for those current smokers who smoked more than 10 cigarettes per day (about a 25% reduction). The large number of individuals in this sample with low macular pigment density motivates the need for population-based assessment of the possibly poor nutritional state of the average American's retina.