Investigation of the relationship between macular pigment levels and rod‐mediated dark adaptation in intermediate age‐related macular degeneration

Abstract

Background: It has been shown that rod-mediated dark adaptation is significantly delayed in ageing, a change which is exacerbated in age-related macular degeneration (AMD). Levels of lutein and zeaxanthin, the two main constituents of macular pigment have been found in rod outer segments, indicating that the macular pigment may have an influence on rodmediated dark adaptation. The aim of this study was to determine if rod-mediated dark adaptation is associated with central macular pigment levels in individuals with intermediate stage AMD. Methods: A cross-sectional observational study included individuals with acuity better than 6/15 Snellen and intermediate stage AMD based on graded fundus photographs using an internationally accepted grading scale. Rod-mediated dark adaptation was assessed at five degrees eccentricity in the superior retina (inferior visual field) using the rod intercept time measure from the MacuLogix AdaptDx. Macular pigment optical density was measured at 0.5 degrees eccentricity using a heterochromatic flicker photometry-based method. Results: Twenty-seven individuals (mean age 76.7 years) with intermediate stage AMD and 23 age-matched normal controls (mean age 74.0 years) were recruited. Rod-mediated dark adaptation was significantly delayed in intermediate stage AMD compared with healthy controls (32.9 minutes versus 10.7 minutes, p < 0.01). There was no statistically significant correlation between the rod intercept time and the level of macular pigment in those with intermediate AMD (r = −0.04, p = 0.85). Conclusion:The results did not support the hypothesis that higher macular pigment is associated with improved rod-mediated performance or that higher levels of macular pigment protect rod-mediated function in intermediate AMD.

Visual Function and Macular Carotenoid Changes in Eyes with Retinal Drusen—An Open Label Randomized Controlled Trial to Compare a Micronized Lipid-Based Carotenoid Liquid Supplementation and AREDS-2 Formula

“…The DAR did not show statistically significant improvements with carotenoid intake over time. The findings agree with a prior report that showed a lack of correlation between MPOD and rod-mediated response and function [58]. The fact that the study participants were individuals with subclinical AMD, and not overt AMD, may have also played a role in this outcome.…”

Local Abundance of Macular Xanthophyll Pigment Is Associated with Rod- and Cone-Mediated Vision in Aging and Age-Related Macular Degeneration

“…We found that increased MPOD abundance was associated with faster RMDA despite being <10% of peak values at the foveal center. It could be argued that a sufficiently high level of MP at 5°eccentricity could delay RMDA simply by reducing the intensity of light reaching the photoreceptors, 77 but we found the reverse. Low values of MPOD at the RMDA test location in our study suggest that light filtration is not a major factor.…”

“…One striking and apparently novel finding is higher levels of MPOD, in early and intermediate AMD compared to normal eyes, by all measures as assessed by objective imaging. Previous studies, all small like ours, have reported that MPOD was the same (Ireland), 69,76,77 or lower (South Korea) 78 in AMD eyes when compared to normal eyes. These findings were obtained by HFP at single 77,78 or several 69,76 retinal test locations.…”

“…Previous studies, all small like ours, have reported that MPOD was the same (Ireland), 69,76,77 or lower (South Korea) 78 in AMD eyes when compared to normal eyes. These findings were obtained by HFP at single 77,78 or several 69,76 retinal test locations. Short-term supplementation trials in AMD eyes have found that BCVA improves months after an MPOD increase, 6,63,65 leading to the conclusion that this lag could not be solely attributable to an increase in optical filtration.…”

Are Current Methods of Measuring Dark Adaptation Effective in Detecting the Onset and Progression of Age-Related Macular Degeneration? A Systematic Literature Review

“…The AdaptDx has a threshold stimulus size of 1.7°-2.0°with a wavelength of 500-505 nm [10, 12-14, 16, 23-38], centred on a bleached area subtending 4°. Eight studies reported that the stimulus was first presented 15 s after bleaching onset [10, 16, 27-30, 35, 37] while others reported that it started immediately after bleaching [24,34]. The most frequently reported maximum test time (or cut-off time) was 20 min [10, 12, 13, 24-26, 28-32, 37, 38] [35] (1 out of 21 studies).…”