Twin study finds genetics a key factor for macular pigment optical density

Genetics are a major determinant of a person’s macular pigment optical density, according to a study in twins.

Shiao Hui Melissa Liew and colleagues in London and elsewhere performed the classic twin study using 76 monozygotic and 74 dizygotic pairs of twins. Subjects ranged in age from 18 to 50 years. Macular pigment optical density was measured psychophysically with heterochromatic flicker photometry and also with an imaging method using fundus autofluorescence. The covariance of macular pigment between the two types of twins was compared.

The mean macular pigment optical density as measured by the flicker technique was 0.43. Using autofluorescence, the mean macular pigment optical density measured at 1· eccentricity was 0.28.

Both types of measurements correlated more highly in the monozygotic than the dizygotic twins. A model combining additive genetic and environmental effects offered the best fit and resulted in heritability estimates of 0.67 for the heterochromatic flicker and 0.85 for the autofluorescence measurements.

The study is published in the December issue of Investigative Ophthalmology & Visual Science.