Funded Grants

Developing sensory-cognitive predictors of everyday functioning with visual impairment

Over 250 million people worldwide suffer from vision loss. While treatments have improved, most patients will have to find ways to deal with their impairment for the rest of their lives. However, existing clinical tests are designed to diagnose the cause and progression of the disease, rather than to test the ability of the patient to compensate for their impairment and their rehabilitative potential. In particular, existing tests are predominantly based on visual acuity and perimetry, yet neither are very predictive of the patient’s everyday functioning. A new breakthrough is required to improve assessment of an individual’s chances of rehabilitation from vision loss.

We hypothesize that the limited usefulness of existing tests for predicting impact and progress stems from the fact that those tests a) ignore important cognitive factors affecting visual information processing, and b) are static, while vision itself is highly dynamic. Specifically, at the cognitive level, several mechanisms determine whether observers can discriminate, attend to, and ultimately become aware of visual information. Moreover, in dealing with their functional limitations, patients are likely to develop compensatory eye and head movement strategies. We start from the premise that natural visual orienting behavior in realistic everyday environments will therefore provide a better reflection and prediction of everyday functioning.

The primary aim of this project is to develop a standardized measure of real-world visual performance for people with vision impairment. We will combine virtual reality with eye and head tracking to develop an index of functional vision that can be obtained from natural, dynamic viewing behavior. We will do so by 1) developing suitable visual environments and tasks for a range of vision deficits; 2) develop eye and head tracking procedures (which is not trivial in cases of visual impairment), and 3) develop suitable models of how eye, head, and navigational movements combine in the visually impaired to predict everyday functioning and well-being. As an initial validation, we will test whether such models vary systematically depending on the type of vision loss, and whether they better predict athletic performance in a group of Paralympic athletes, as they are some of the best-known examples of people who have adapted to their impairment. The long-term practical goal is to provide clinicians with a tool to objectively assess the efficacy of real-world visual performance, from sensory to cognitive levels. At the shorter term, the project will deliver invaluable scientific impact by 1) developing suitable methodologies for measuring orienting behavior in the visually impaired, 2) validating existing scientific models of eye-head coordination that so far have been based on normally seeing populations, and 3) establishing a large publicly available corpus of orienting data in impaired populations for the scientific community to use.