Research and development of a low-cost, portable visual field testing platform using a smartphone and virtual reality headset for the early detection of glaucoma

Glaucoma is the leading cause of irreversible blindness worldwide, affecting about 64 million people. A large proportion of glaucoma cases worldwide are undiagnosed or sub-optimally managed. More than half of people living with the disease, in low-income countries, are unaware of the condition until it progresses to an advanced stage, resulting in visual impairment. Since adequate treatment significantly slows or halts progression of the disease, early detection of cases is considered important. Visual field test is one of the major tests for screening and diagnosis of glaucoma. The test assesses central and peripheral vision of each eye separately in order to detect vision loss, which, in case of glaucoma, gradually progresses from the periphery to the center. The test is mostly performed with standard automated perimetry equipment which is expensive and not easily portable. For people living in rural areas of low-income countries with limited access to ophthalmic care, glaucoma screening and diagnosis testing through visual field test is near inexistent. If an affordable alternative to the standard automated perimetry(SAP) equipment would become available, it is likely that more glaucoma cases could be detected, especially in rural areas where the burden of the disease is most significant. This doctoral dissertation describes the design, development and assessment of a smartphone based low-cost and portable glaucoma visual field screening platform. This doctoral dissertation aims to explore the feasibility of a low-cost and portable visual field screening platform for the early detection of glaucoma, using a smartphone and a virtual reality(VR) headset. To address this aim, the following research questions will be answered. RQ1: What are the needs and preferences of ophthalmic professionals and patients in rural areas of developing countries towards a visual field screening platform using smartphone and VR headset? RQ2: How do we design and develop a mobile app for visual field screening tailored to the needs of ophthalmic professionals and patients from rural areas? RQ3: What are ophthalmic professionals' use and acceptance of a glaucoma screening platform using smartphone and VR headset? RQ4: What is the accuracy of a glaucoma screening platform using smartphone and VR headset compared to a gold standard perimetry equipment? RQ5: What is the sensitivity and specificity of a glaucoma screening platform using smartphone and VR headset? An adopted version of the user-centered design (UCD) process was followed to address most of the research questions. First, a user and task analysis is conducted in Southwest Ethiopia to identify requirements for a visual field screening application. Multiple contextual requirements were identified during this step using field observations, semi-structured interviews with ophthalmic professionals and patients. Next, design parameters and devices (smartphone and VR headset) were selected based on the requirements identified. Next, a prototype screening Android app, glaucoma easy screener(GES), is developed. Following this, the screening app was assessed for usability and acceptability among ophthalmic professionals in Southwest Ethiopia. OPs perceived GES as easy-to-use, enabling the screening of glaucoma screening tests, especially during outreach to rural areas. Even older patients from rural areas, with limited familiarity with technology, were able to perform the test with GES, and valued a 'technical' assessment. Next, clinical accuracy of GES was evaluated by comparing its results against gold standard SAP equipment. There was good level of agreement (above 85%) based on results of 36 eyes. Finally, an assessment of sensitivity and specificity was conducted by testing 40 glaucomatous eyes and 20 normal eyes with the screening platform. Receiver Operator Characteristic (ROC) was used to determine an optimal cut-off points that yields the best combination of sensitivity and specificity. A cut-off value of 3 missed point yielded an acceptable trade-off between sensitivity (90%) and specificity (85%). These findings suggest that low-cost and portable glaucoma visual field screening using smartphone and VR headsets is feasible.

Publication year:2022

Accessibility:Open