Optimising Visual Acuity Measurement in Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of visual impairment in the UK. The condition is characterised by damage to the region of the retina (macula) responsible for detailed central vision, this leading to problems with tasks such as reading and face-recognition. The ability to accurately measure vision is central to the detection and management of AMD. The most common test (visual acuity) typically requires patients to identify black letters of varying size on a white background, with the smallest letter read representing the limit of vision. Conventional tests are however known to be variable, making it difficult to determine if a true change in vision has occurred. Previous work has found the Moorfields Acuity Chart, which contains specially constructed letters composed of a black core and white border, to be more sensitive to early AMD compared to standard charts. Despite this advantage, it is unclear if there is an associated increase in measurement variability with the Moorfields Acuity Chart and if this changes with the severity of disease. In this study, the relationship between vision test sensitivity and measurement variability will be quantified with both conventional visual acuity tests and the new Moorfields Acuity Chart to identify the optimal vision test to detect and monitor AMD in the clinic.