Title: Development of a new platform for monitoring vision function in glaucoma
Funder: Department of Health and Social Care

Abstract: The MMDT, published as one of the &ldquo;Big Ideas for the Future&rdquo; by the RCUK in 2011, provides a more accurate test of visual function being resistant to the effects of cataract and refractive error (ref.2). It can be presented on an affordable LCD platform. Previous work established the suitability of the test stimuli (moving lines) for VF loss detection (supporting data, Fig.1), for which it won the MRC Translational Research Innovation Award (2008). At present, the test identifies whether retinal sensitivity is above/below a limit based on normative data (i.e. within normal limits or outside normal limits ). We propose further development work to adapt the test to measure retinal sensitivity across the whole range from normal-seeing to blind. This is an essential step for monitoring VF deterioration in diseases such as glaucoma. To provide a competitive solution that will promote adopting the new platform, the proposed new perimeter needs to present the current standard automated perimetry (SAP; circular spots of light) test, in addition to the MMDT, so that patients already under monitoring can be transitioned onto the new test. Thus, the proposal aims to provide evidence for the suitability of a LCD platform to present both SAP and MMDT stimuli (stage 1) across the range required to monitor glaucoma (SD Fig's 2&3) and to define the relationship between stimuli measurements (stage 2). A new, efficient strategy for presenting stimuli (algorithm), to obtain more precise measurements for monitoring glaucoma deterioration in a patient will be developed in stage 3 and applied to both stimuli. In stage 4, the algorithm will be evaluated against a conventional test algorithm. Throughout the study, patients and end users experiences will be registered to improve VF testing. This proposal will produce a highly competitive solution for clinical perimetry. The new hardware platform will greatly reduce space needs and costs while being more adaptable to present different stimulus types and support future developments. Stage 1: To establish the suitability of the LCD screen for SAP, we will measure the LCD screen characteristics that affect stimulus brightness and duration and calculate the stimulus parameters required to obtain equivalent retinal sensitivity measurements to those on standard hardware ( bowl perimeter). We will determine, in healthy subjects and in patients, the dynamic range of the LCD monitor, using standard stimuli, and compare it to a bowl perimeter. We aim for a difference between bowl and LCD measurement within 1 unit (1dB). Sample size: 52 subjects. Stage 2: Retinal sensitivity will be measured at various locations with conventional and MMDT stimuli, to generate an equation(s) to convert sensitivity measurements between stimulus types (for patients transitioning from conventional to MMDT tests). Data will be collected on 28 subjects with moderate to low retinal sensitivity to supplement existing preliminary data (SD Fig.4). Stage 3: New, efficient strategy for presenting stimuli will be developed in collaboration with patients, clinicians and technicians. Increased efficiency will be achieved using prior knowledge of the patients VF, integrating information of the anatomical correlation between VF locations (SD Table 2, Fig5), varying stimulus size, and by not testing already-blind locations. We aim to reduce test variability by 20%, a figure published to have a measureable clinical benefit. Pilot data will be obtained on 10 patients. Stage 4: The new strategy will be tested against a current reference standard (the SITA algorithm of Humphrey perimetry) for a 20% reduction in variability. Sample size: 100 patients (see flow of patients through stage 4 in SD Fig.6). Stage 5: To assess patients and end users views regarding VFs and to collaborate in the development of the new strategy.

Lay abstract: Glaucoma is the world s leading cause of blindness. Patients experience a gradual loss of peripheral, then central vision. Glaucoma affects 5% of people over 80 years and there is an even higher prevalence in some racial groups and in people who have a family history of the disease (ref.1). However, glaucoma may occur at any age particularly in those over the age of 40 years. If glaucoma is detected early, treatment can prevent vision loss in most cases. The effectiveness of treatment is assessed by regular monitoring of the patients vision through a visual field (VF) test on an instrument called the perimeter. Perimeter measurements are very variable, requiring many tests over a long period to determine the extent of vision loss. In addition to the inconvenience caused to patients, the contribution of these many tests to the financial burden on the NHS is increasing with the growing aging population. Existing perimeters are expensive and bulky and as glaucoma is a chronic disease, patients need lifelong monitoring, requiring multiple tests and clinic visits. To address these unmet needs, we propose to develop a new machine and software platform that can be used to monitor glaucoma more efficiently and improve patients experience. Our previous work on developing tests to diagnose glaucoma won the MRC Translational Research Innovation Award in 2008. Using knowledge from this previous work, together with new data from our group and from the literature, we will develop new tests that are more accurate and precise. The LCD monitor proposed for the new perimeter will save cost and space, and is totally adaptable and transportable. The platform will also provide greater accessibility to data and allow data to be exported to electronic patient records. The duration of the proposed work is 3 years.

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