Abstract
Retinal pathologies causing central vision loss, such as macular degeneration, are an increasingly common health problem, affecting elderly populations worldwide. Deprived of central vision, patients learn to use peripheral vision for daily tasks. Different patients compensate to different degrees: two patients with similar retinal damage or visual acuity score might exhibit very different performance in higher-level, cognitive tasks, indicating different levels of compensation.
A first step toward understanding how people compensate for loss of central vision requires individual quantification of this compensation. This has historically been very difficult, since each person's retinal degeneration and compensation vary greatly. Few studies so far have tried to bridge the gap between anatomical examinations of the retina and cognitive evaluations.
Here we propose a method for quantifying the level of compensation of patients suffering from central vision loss. This involves linear regression comparing a composite score of low-level visual assessments (contrast sensitivity, visual acuity and a novel eccentricity-weighted measure of visual sensitivity from microperimetry) to high-level cognitive measures that require vision (attention, emotion recognition, and visual function questionnaire). The regression line describes a profile of average compensation. Individual patient’s distances from the regression line are the estimated "compensation scores".
In 22 MD participants, composite scores of low-level vision correlated significantly with composite scores of high-level tasks requiring vision, suggesting an overall strong relationship between low-level vision and higher-level processes involving vision. Importantly, there were deviations from this relationship, indicating that some patients compensated more completely than others for impaired vision. We will discuss the benefit of including direct measures of retinal health along with behavioral measures.
This approach paves the way for future work exploring the neural mechanisms of compensation for central vision loss, and these methods can be adapted to examine compensation in other modalities.