An Evaluation of Two Candidate Functional Biomarkers for Age-Related Macular Degeneration

Binns, A. M., Mckeague, C. & Margrain, T. (2014). An Evaluation of Two Candidate Functional Biomarkers for Age-Related Macular Degeneration. Optometry & Vision Science, 91(8), pp. 916-924. doi: 10.1097/OPX.0000000000000318

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Abstract

PURPOSE: To evaluate the inter-session repeatability of the Colour Assessment and Diagnosis (CAD) test and a novel 14-Hz flicker test in a population of healthy participants in order to provide benchmark data for their use as functional biomarkers for age-related macular degeneration (AMD).

METHODS: Visual function was assessed using both techniques in 30 healthy adults (mean age 36.3 ± 14.1 years) on 2 separate days. Inter-session repeatability of RG and YB CAD thresholds and 14-Hz flicker thresholds was assessed by determining their coefficient of repeatability (CoR).

RESULTS: The CoR was calculated to be 0.39 CAD units (17.0%) for RG thresholds, 0.43 CAD units (31.1%) for YB thresholds and 0.015 (53.4%) for 14-Hz flicker contrast thresholds. On average, thresholds improved by 4.72% (RG), 6.33% (YB) and 13.3% (14-Hz flicker) between visits 1 and 2, suggesting a small but consistent learning effect. The CoR for all parameters was relatively small compared to the mean thresholds obtained (RG: mean 2.27 ± 4.58, CoR 0.39; YB: mean 1.37 ± 0.55, CoR 0.43; 14-Hz flicker: mean 0.028 ± 0.01, CoR 0.015).

CONCLUSIONS: This study has described the repeatability of the CAD and 14-Hz flicker tests. The data can help clinicians decide if the results from repeated measures are of clinical significance. Despite pre-test training, there was some evidence of a learning effect. Therefore, clinical trials using these techniques should ensure training is sufficient to minimize these effects.

Item Type: Article
Additional Information: This is a non-final version of an article published in final form in McKeague, Claire, Alison M. Binns, and Tom H. Margrain. "An Evaluation of Two Candidate Functional Biomarkers for AMD." Optometry & Vision Science 91.8 (2014): 916-924.
Uncontrolled Keywords: repeatability, age-related macular degeneration, biomarkers, color vision, flicker
Subjects: R Medicine > RE Ophthalmology
Divisions: School of Health Sciences > Department of Optometry & Visual Science
URI: http://openaccess.city.ac.uk/id/eprint/3769

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