ORCID

Abstract

Age-related macular degeneration is a common ocular condition in the older adult population, being the leading cause of visual impairments in industrialised countries. The prevalence of age-related macular degeneration is expected to increase along with increased life-expectancy. The early stages of age-related macular degeneration often present no noticeable symptoms; however, visual function may be impaired, particularly under low light conditions. An initial impairment tends to occur in the parafoveal region where rod photoreceptors are denser, as these photoreceptors were shown to be more prone to dysfunction than cone photoreceptors in early stages of age-related macular degeneration. Therefore, testing for this early dysfunction may prove to be an useful clinical tool in the assessment and monitoring of individuals with early retinal changes, which may impact various aspects of visual function, including spatial and temporal function, adaptation mechanisms and chromatic function, albeit such impairments may be more evident at later stages of the pathology. Considering the lack of symptoms and reduced signs at the early stages, the traditional methods to assess visual impairment, such as visual acuity tests with high contrast letter charts, may not be sufficient in the detection of dysfunction and also, render unusable in the tracking of progression in age-related macular degeneration from early to later stages. Assessing visual function with low contrast and under low light levels may provide deeper insight and allow for the detection of possible dysfunctions at early stages of the pathology. Contrast sensitivity is a spatial vision aspect shown to be impaired at different stages of age-related macular degeneration, as studies using Pelli-Robson charts and sinusoidal gratings have demonstrated significant reduction in this visual function. Also, the reduction in contrast sensitivity has not only be found in the central vision, as decreases in paracentral and peripheral contrast sensitivity have been reported. However, assessing paracentral or peripheral contrast sensitivity through these methods can be time-consuming and impractical for daily optometric practice.The research presented in this body of work, aims to explore and expand the knowledge around paracentral contrast sensitivity function under low light levels in healthy adults and individuals with age-related macular degeneration. In this study a psychophysical test that takes into account age-related macular degeneration pathogenesis is designed to address the limitations of existing tests in the assessment of individuals with age-related macular degeneration. The goal is to develop a rapid, quantitative assessment method for macular function, affordable, practical and adaptable to be applied in daily optometric practices enhancing optometrists' ability to screen and monitor macular dysfunction in individuals with age-related macular degeneration, improving their outcomes.

Awarding Institution(s)

University of Plymouth

Supervisor

Stephanie Mroczkowska, Luis Garcia Suarez, Leanne Smewing, Mahesh Joshi

Document Type

Thesis

Publication Date

2026

Embargo Period

2026-04-20

Deposit Date

April 2026

Creative Commons License

Creative Commons Attribution-NonCommercial 4.0 International License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

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