Abstract
Purpose:
To investigate whether there is any relationship between macular pigment optical density (MPOD) and glaucoma-related structural parameters including the ganglion cell complex (GCC), retinal nerve fibre layer (RNFL), foveal full and inner retinal thickness and standard automated Humphrey 10-2 for macular testing. This study comprises an analysis of the baseline structural data collected as part of the Macular Pigment and Glaucoma Trial (ISRCTN56985060).
Methods:
All glaucoma participants underwent a detailed slit-lamp exam, MPOD measurement (heterochromatic flicker photometry using the Macular Densitometer), and spectral domain optical coherence tomography (sdOCT) imaging of the optic nerve head and macula (SD-OCT, Optovue). Results were analyzed using the SPSS statistics software (version 21).
Results:
A total of 67 glaucoma subjects were recruited to the trial, of which 38 were male, and 29 female (35 primary open angle glaucoma, 23 low-tension glaucoma, 7 pseudoexfoliation glaucoma, 2 pigment dispersion glaucoma). The mean age of participants was 64.8 years (range 36-84 years). Participants with sub-normal GCC values exhibited statistically significantly lower MPOD (at 0.25 degrees and 1 degree of retinal eccentricity) values compared to those glaucoma subjects demonstrating normal GCC values [0.25 degrees - mean MPOD = 0.20±0.13 (sub-normal GCC group) versus 0.32±0.11 (normal GCC group); p=0.004); 1.0 degrees (0.11±0.06 vs 0.18±.09; p=0.014) respectively. There was no significant relationship observed between MPOD and RNFL. An inverse and statistically significant correlation between MPOD (at 0.25, 0.50 and 1.0 degrees of retinal eccentricity) and glaucoma duration (r = -0.302 to -0.369; p = 0.032 to 0.039).
Conclusions:
There is emerging evidence that the macula is affected early in glaucoma. Our previous study has demonstrated that glaucoma patients have reduced MPOD. Here, our baseline results suggest a linear relationship between MPOD and GCC. Furthermore, the association between MPOD and duration of glaucoma is suggestive of a potential loss of MP over the time course of the condition, perhaps as a consequence of longitudinally increased oxidative stress or compromised ocular blood flow levels.
Keywords: 587 macular pigment •
531 ganglion cells