Description
- Abstract:
- Age-related macular degeneration (AMD) is the leading cause of blindness in people aged 65 years and over in western countries. As the senior population grows, it is expected that the incidence of AMD will increase proportionately. The putative protective role of macular pigment (MP) in the retina against actinic short-wave (SW) light damage and light-driven metabolic damage, both of which may contribute to the onset of AMD, supports the need for a non-invasive, valid, and accurate method that allows the in vivo measure of MP. Heterochromatic flicker photometry (HFP) is the most commonly utilized method for this purpose. HFP is a psychophysical method that compares measures taken in the fovea (where MP is most heavily deposited) and in the parafovea (where MP is optically immeasurable) in order to obtain a measure of the macular pigment optical density (MPOD). Any method that relies on a comparison at different retinal loci relies upon the assumption that the underlying response mechanism has the same relative spectral sensitivity at both sites and that the mechanism responds in a linear manner under all measurement conditions. In this study the spatial, temporal and luminance parameters of the method are varied in order to test potential sources of non-linearity. The stimulus edge-effect which allows mapping of MPOD spatial distribution is explored. And, the often seen slight underestimate of MPOD at short waves when compared to a spectral MPOD template is examined. The results of this study indicate that across a wide range of stimulus parameters, often beyond a normal working range, the responding mechanism behaves in a univariant manner, i.e., linearly. The stimulus edge-effect holds almost perfectly to a retinal eccentricity of 1.0 degree, and the SW underestimate is well-described by the possible presence of two other inert SW-absorbing pigments. A conclusion that HFP is a valid and accurate measure of MPOD is supported by the results reported here.
- Notes:
- Thesis (Ph.D. -- Brown University (2011)
Access Conditions
- Rights
- In Copyright
- Restrictions on Use
- Collection is open for research.
Citation
Smollon, William Evans,
"The Influence of Spatial, Temporal, and Luminance Stimulus Conditions on Macular Pigment Absorbance Measures Using Heterochromatic Flicker Photometry"
(2011).
Psychology Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z03T9FGB
