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Everyday visual function and the visual experience in dry age-related macular degeneration

Taylor, D.J. (2018). Everyday visual function and the visual experience in dry age-related macular degeneration. (Unpublished Doctoral thesis, City, University of London)

Abstract

Dry age-related macular degeneration (AMD) is a common eye condition, which causes progressive loss of central vision; there is currently no treatment. The live studies presented in this thesis aimed to explore different aspects of everyday visual function and the experience of living with dry AMD. In the first study, a systematic review of the literature surrounding quality of life and “real-world” visual ability in AMD was conducted. Several domains of everyday life affected by AMD were identified; these had been investigated using a wide variety of study designs. However, only 4% of studies meeting inclusion criteria specifically investigated individuals with dry AMD. In the second and third studies, people (>60 years, logMAR binocular visual acuity of 0.7 or better) categorised with varying severities of dry AMD performed two previously validated computer-based real-world visual tasks. Comparisons for both tasks were made against a 90% normative limit for the outcome measures established in age-related peers with healthy vision. In a search task, participants were instructed to find items within digital photographs of everyday indoor and outdoor scenes. Sixty-one percent of participants with dry AMD, (including all of those with late dry AMD) exceeded the 90% normative limits for average search time; this was statistically significant (Fisher’s exact test, p < 0.0001). In a face recognition task, participants completed a modified version of the Cambridge Face Memory Test. Percentage of correctly identified faces was used as an outcome measure. Five (17%) participants with dry AMD scored worse than the 90% limit (Fisher's exact test, p=0.46); four of these had fovea-involving geographic atrophy. In the fourth study, volunteers with dry AMD described their visual symptoms in an interview and were asked to comment on the realism of a photograph typically used to simulate vision in AMD. Interview transcripts underwent content analysis. The most frequently used visual symptom was blur (n=13) followed by missing part/s (n=10) and distortion (n=7). Seventy-six percent (95% confidence interval 53-92%) of the participants rejected the realism of a popular image often used to portray the visual symptoms of AMD. In a fifth study, a novel test measuring mobility anxiety was introduced. Participants were shown a series of short movies of navigation through real-world mobility scenarios and were asked to press on a button during scenes which would cause them anxiety or discomfort. Pressure on the button was recorded throughout the test and this was used as an outcome measure. People with intermediate and late AMD applied more pressure to the button, on average, than those with early and no AMD (Kruskal-Wallis test, p=0.04). Situations involving negotiating stairs were identified as particularly problematic. To conclude, these studies spotlight the problems people with dry AMD have with visual tasks. In addition, the tests described in this thesis may have potential to be used as patient- based outcome measures for clinical trials for future treatments for dry AMD. Moreover, findings reported in this thesis may help clinicians with patient management and expectations, and should inform future patient, public and professional education about dry AMD.

Publication Type: Thesis (Doctoral)
Subjects: R Medicine > RE Ophthalmology
Departments: Doctoral Theses
Doctoral Theses > School of Health Sciences Doctoral Theses
School of Health Sciences > Optometry & Visual Science
URI: https://openaccess.city.ac.uk/id/eprint/21727
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