Macular Pigment Optical Density (MPOD), Serum C-Reactive Protein (CRP), and Serum Lutein and Zeaxanthin (L&Z) in Age-Related Maculopathy (ARM)

Abstract

Purpose:: To report the relationship between MPOD and serum levels of CRP and L&Z in subjects with ARM.

Methods:: We studied 112 subjects with ARM [mean age: 79.4 yo, 90% White, 56% females, 46% lutein supplement users (LSUs)] participating in ARMA, an ancillary study to Health ABC. Fundus features were graded in a blinded fashion. By most severely affected eye criteria, the majority of ARM cases met the definition for AREDS category 3 (76%). MPOD estimates could be obtained by heterochromatic flicker photometry at 0.5 degrees of eccentricity from the fovea in 83 (74%) of the affected participants (96% of which had AREDS category 3 ARM). Fasting serum samples were collected at time of visit and analyzed according to standardized protocols. L&Z and CRP were not normally distributed and were ln-transformed.

Results:: The proportion of LSUs was the same in controls and in newly diagnosed cases of ARM (37%). MPOD in newly diagnosed cases (0.34 +/- 0.20, n=71) was not different from controls (0.35 +/- 0.21), despite serum ln-levels of L&Z (2.87 +/- 0.56 ug/dl) and CRP (1.19 +/- 1.08 ug/ml) being respectively lower (p=0.014) and marginally higher (p=0.044) in ARM than in controls (ln-L&Z: 3.05 +/- 0.47 ug/dl; ln-CRP: 0.70 +/- 1.24 ug/ml). Compared to controls, serological differences were significantly greater in bilateral cases (n=37) of newly diagnosed ARM (ln-L&Z: 2.78 +/- 0.57 ug/dl, p=0.005; ln-CRP: 1.53 +/- 1.04 ug/ml, p=0.003). The proportion of LSUs in previously diagnosed cases of ARM (n=41) was twice as large (63%). Consistent with this pattern, both serum ln-L&Z (3.36 +/- 0.62 ug/dl, p=0.001) and MPOD (0.44 +/- 0.20, p=0.024) in previously diagnosed cases of ARM were significantly higher than controls, and ln-CRP was no longer significantly higher than in controls (1.08 +/- 1.04 ug/ml, p=0.271).

Conclusions:: In newly diagnosed cases of ARM, MPOD is not reduced despite serological evidence of reduced L&Z levels. Higher CRP levels in bilateral ARM suggest that circulating CRP is an indicator of inflammation that is proportional to the extent of macular disease. On average, MPOD of subjects with ARM appears to remain responsive to L&Z dietary supplementation. L&Z intake modifies CRP levels and confounds association studies of ARM.

Keywords: macular pigment • age-related macular degeneration • inflammation