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K.A. Haase, M. Engles, R. Hammond, B. Wooten; The Relation Between Macular Pigment Density and Hyperacuity . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4568.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Schültze (1866) proposed that macular pigment (MP) serves to improve acuity by reducing the deleterious effects of chromatic aberration. Although proposed well over a century ago, the hypothesis has never been tested. We chose to begin evaluating the Acuity Hypothesis by measuring MP levels and acuity in the same observers. Hyperacuity was chosen for the initial study because it is known to yield the finest spatial discrimination. Methods: 21 young (average age = 20 yrs) healthy subjects were assessed. Peak MP density was measured using HFP in Newtonian view. Hyperacuity was measured using a vernier offset task and a two–alternative forced–choice procedure on a white (17 cd/m2) and on a yellow background (16 cd/m2) that was 0.5° diameter. The thin vernier lines (1–min width) were superimposed on a diffusing plate backlit by combined blue (peak = 460 nm) and yellow (peak = 570 nm) LEDs or just yellow LEDs (the white and yellow conditions, respectively). The subject’s head was stabilized with a head–rest assembly and their adaptive state was controlled using a constant white surround (11 cd/m2). Results:MPOD density ranged from 0.25 to 1.25. Hyperacuities ranged from 2 to 10 arc seconds (M = 5 seconds). There was no significant relation between MP and hyperacuity measured in the white or yellow conditions. This lack of significance, however, may have been due to insufficient statistical power. Average hyperacuity was significantly higher in the yellow versus the white condition. Conclusions: These results lead to two tentative conclusions. First, at least for hyperacuity, the Acuity Hypothesis has not been supported. Hyperacuity could be related to MP density via a protective mechanism but older subjects showing loss would need to be tested to address this possibility. Second, since hyperacuity is better on the yellow background than on the white background, and the yellow background is, as expected, independent of levels of MP, a tentative Conclusions: follows: The improvement in hyperacuity on the yellow background can be attributed to mechanisms determining color appearance, per se, and is not due to the lack of short–wave light.
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