Title: A new instrument for the early detection and monitoring of Age Related Macular Degeneration (AMD)
Funder: Department of Health (England)

Abstract: This research will utilize the latest version of an instrument, which is now called the FDA-01. It was built in i4i project ll-FS-0110-14036 (completion date December 31st 2011). The device is designed to characterize the dynamics of sensitivity recovery during Dark Adaptation (DA). In order to obtain a DA curve (see previous i4i report for parameters) a series of visual thresholds are obtained for around 15 minutes after exposure to a bright light. Observers are required to press a button when they first detect a dim light viewed in the peripheral field (11 deg). As the DA process develops, sensitivity increases and the light is gradually reduced in intensity. Sensitivity is plotted against time to produce a DA curve. The duration of the test is influenced by the magnitude of the pre-test bleaching light which saturates the rods. Uniquely in our implementation of the procedure, the target is superimposed on a deep red background to which the rods are insensitive. The research will proceed in 2 phases. First, the instrument will be developed from its present form, the FDA-01, described in the previous i4i report, in to a pre-production prototype. Phase 1 will be composed of the following steps. UoM and Elektron will act in parallel in this phase; UoM will conduct research using the FDA-01 to determine the specification of the new lighting board which will provide the bleach. They will also finalize the algorithm for the threshold measurement method and specify how the bleach will be customized according to the characteristics of the observer. Age, pupil size, flicker sensitivity and optical density of ocular media will be taken into account in this calculation. Note that the intensity of the bleach influences the extent to which cones are desensitized and therefore the duration of the test. This is a crucial step because controlling the bleach will provide control over the overall time of the test . The design and specification features obtained during these activities will be conveyed to Elektron over the course of the first 6 months, so they can meet the delivery date for the FDA-02 which will be 9 months after the start of the project . In the second phase, the new version of the instrument, the FDA-02, will be tested at UoM by comparing the results obtained from a group of 20 AMD patients and 20 age-matched normals. Participants will be categorized by our ophthalmological colleagues Mr Aslam and dr Parry at the Manchester Royal Eye Hospital (MREH) according to fundus photographs and a formalized ophthalmological examination based on eye disease, medical history and/or medication to exclude other ophthalmic disease and any systemic condition. Many participants will be recruited from MREH. The observers’ opinion of their night vision will be assessed with a specifically-designed questionnaire regarding quality of life and night vision (LLQ, Owsley et al 2006). The participants will be able to comment on the task they are asked to perform via patient panels and a series of questionnaires. In addition to DA, we will measure the observers’ visual acuity and photostress recovery which is said to be abnormal in AMD. The sample size of 20 is based on a mean for the slope of the rod-mediated DA curve of 0.019 ±0.07 for the age matched normals and 0.11 ± 0.1 for the AMD patients. These values are based on our previous i4i report (ll-FS-0110-14036 ) and a conservative estimate of the values for AMD patients based on our own published data. The power of this study will be 81%.


Research activity codes: 4.1 DISCOVERY AND PRECLINICAL TESTING OF MARKERS AND TECHNOLOGIES
Health categories: EYE