Macular pigment optical density measurement: a novel compact instrument

A compact device to derive the optical density of human macular pigment (MP ) using heterochromatic flicker photometry is described. The validity of th e system is assessed by measuring the optical density spectra of MP in 12 h ealthy subjects and comparing this with well-established previously publish ed values. The mean spectral absorbance characteristics of MP across subjec ts corresponds well with accepted values. As reported in other studies, our measurements show a wide Variation of MP optical densities between individ uals. In our technique within-subject variability is low; standard deviatio ns are between 0.025 and 0.15 in most cases. The overall optical density of MP ranged from 0.08 to 0.84 with a mean of 0.496 and standard deviation of 0.257 at 460 nm. The stimulus size was 0.95 degrees. The unique feature of the technique is that it allows free viewing (not Maxwellian View) of the stimulus, it can be conducted easily and quickly and does not need frequent re-calibration. (C) 2000 The College of Optometrists. Published by Elsevie r Science Ltd. All rights reserved.