Document Type

Theses, Ph.D


Available under a Creative Commons Attribution Non-Commercial Share Alike 4.0 International Licence


Optics, Ophthalmology

Publication Details

Submitted to Technological University Dublin for the award of Ph.D, November 2012.


Abstract Objectives: 1. To explore visual performance status through a range of psychophysical methods beyond corrected distance visual acuity (CDVA), in subjects with age-related macular degeneration (AMD). 2. To investigate the effects on these visual performance parameters in subjects with neovascular age-related macular degeneration (nv-AMD) and in subjects with early AMD undergoing anti-VEGF (vascular endothelial growth factor) therapy and macular carotenoid supplementation, respectively. 3. To understand the role of a supplement containing meso-zeaxanthin (MZ; the third, and currently least explored, macular carotenoid) on the augmentation of macular pigment (MP), on visual performance and on disease progression (graded according to the AREDS [Age-Related Eye Disease Study] criteria), in subjects with early AMD. 4. To explore the impact of macular carotenoid supplementation on vision in subjects presenting with atypical macular pigment optical density (MPOD) spatial profiles at baseline. Outcomes: This study has shown that CDVA is not the most appropriate measure of visual function and does not reflect retinal morphology in cases of early AMD or in cases of nv-AMD. Retinotopic ocular sensitivity (ROS), however, appears to be a more reflective measure of disease severity, where it correlates well with AMD-severity grade (in cases of early AMD) and also with mean foveal thickness (MFT; in cases of nv-AMD). In eyes with nv-AMD undergoing monthly intravitreal ranibizumab injections, there have been demonstrable improvements in a range of parameters of visual function, namely, contrast sensitivity (CS), glare disability (GD), and ROS but no significant change in CDVA, despite a reduction in MFT. MP can be augmented, and CS enhanced, in subjects with early AMD who receive supplemental macular carotenoids. Subjects with low baseline central MPOD had the greatest increases in MPOD and the greatest improvements in CS, when compared with subjects with medium or high baseline MPOD, suggesting that the 4 optimisation of CS (and putatively visual performance in general) is somewhat dependent on central MP levels. The literature review has concluded that supplementation with the macular carotenoids offers the best means of fortifying the antioxidant defenses of the macula, thus putatively reducing the risk of AMD and/or its progression, and of optimising visual performance. Conclusions: The findings of this work suggest the incorporation of tests, complimentary to CDVA, such as CS, GD, and particularly ROS, when attempting to understand disease severity in cases of AMD. In terms of monitoring change over time, the results of this study do seem to indicate that measures of ROS may be particularly useful in monitoring subjects with nv-AMD, while measures of CS and GD may be more apt in monitoring change in subjects with early AMD. Macular carotenoid supplementation can enhance visual performance in subjects with early AMD.