The Development of TREYESCAN: An Eye Tracking Test for the Measurement of Compensatory Eye Movements for Driving with Visual Field Loss

The project presented in this thesis centers around the development of TREYESCAN: Traffic Eye Scanning and Compensation Analyzer. A test designed to quantitatively assess compensatory viewing abilities on a wide screen in individuals with visual field loss, which allows for unrestricted head and eye movements. Establishing vision standards for determining fitness to drive is challenging, considering the negative consequences of driving cessation on mobility, independence, and quality of life. The impact of peripheral visual field loss on driving performance is established, but the precise level of loss incompatible with safe driving remains uncertain, as compensation abilities vary widely between individuals and increased scanning is reported to aid adaptation. Given the relatively weak evidence supporting current vision standards, there is a need to explore whether compensatory eye movements enable individuals with varying levels of visual field loss to effectively perceive their surroundings while driving. The aim is to distinguish between effective and ineffective compensatory scanning in individuals with visual field loss, focusing solely on this skill without measuring additional abilities associated with driving. Therefore, TREYESCAN can offer advantages over static visual field testing, since eye and head movements are permitted for compensation of visual field loss. Chapter 1 provides a general introduction on glaucoma, the primary cause of visual field loss in the elderly population and the leading cause of irreversible blindness worldwide. Primary open-angle glaucoma (POAG) represents a significant public health concern with a global prevalence of 2.4% in the population over 40 years old, impacting 68.56 million individuals in 2021. The chapter discusses the impact on the optic nerve and the visual field, and the importance of timely detection and intervention. The phenomenon of unawareness of visual field loss in glaucoma patients, compensatory eye movements, and the challenges of driving with visual field defects are also explored. Presently, the Esterman visual field test, a suprathreshold binocular test, serves as the standard for assessing the visual field in glaucoma patients undergoing driving evaluations in the Netherlands. In Chapter 2, an analysis of data from the CBR (Dutch driving test organization) is conducted to determine the predictive value of the Esterman visual field test on the outcome of on-road driving tests. Subsequently, the TREYESCAN was developed, with detailed accounts of the developmental stages presented in Chapters 3 and 4. Chapter 3 covers the validation and development of the setup and open-source software of the TREYESCAN. Chapter 4 outlines procedures involved in traffic scene recording, as well as pilot measurements in normally-sighted individuals for the selection of suitable scenes and Areas of Interest (AOIs). Chapter 5 presents the TREYESCAN case-control study results, involving glaucoma patients at various stages of disease progression and control participants. The relationship between visual field loss and compensatory eye movements is explored. Chapter 6 includes a summary of this thesis’ main findings, leading to a subsequent general discussion and conclusion.