Using technology to aid functional vision

Professor Paul McGraw, Nottingham University - £167,082

December 2019 – June 2024

What’s the problem?

People with macular disease often lose some or most of their central vision due to the deterioration of their macula. To compensate for the loss in central vision, using the remaining peripheral (side) vision is often required. This is called eccentric viewing. 
A key problem is that the areas of the eye used in eccentric viewing are not well suited to fine-detailed tasks. Some people rely on technology like apps, tablets and smartphones to help, although many still have trouble reading and seeing detailed images. It’s thought that changing how these apps display images could improve reading speed, face recognition and fine detail vision (acuity).

What did the researchers do?

Professor McGraw and the team at the University of Nottingham used a technique called Contrast Polarity Reversal (CPR) to change the way an image is displayed. 
CPR alternates the polarity of an image, meaning the light and dark areas of the image are swapped. Imagine looking at a black-and-white photo: if you reverse the contrast polarity, the black areas become white, and the white areas become black. The researchers previously found this technique improves the visibility of moving targets. 
The current project assessed the effect of CPR on three different tasks involving acuity, face recognition and reading. They tested this in both healthy patients and those with central vision loss. They also assessed different forms of CPR in combination with other digital image manipulation techniques. This involved sharpening the images, making the outlines in an image bolder, changing the background pattern or the speed at which the image contrast polarity alternates. 

What did the researchers find?

They found when targets are presented on a background that is structured, more akin to normal viewing situations, CPR applied to the target or the background significantly improved visual performance. Unfortunately, CPR did not help facial recognition, however, alternating between a normal face and a digitally sharpened version of the face resulted in significant improvements in recognition. 
These benefits and improvements to peripheral visual performance were more pronounced in participants with central vision loss. Researchers also noted that with practice, reading performance for CPR text improved but normal text did not, suggesting training may be required to realise the benefits of CPR for reading. 

What’s next?

The results of this project could help researchers in the future develop visual aids or smartphone apps to better assist people with central vision loss and improve their ability to use peripheral vision. The next step for the team at Nottingham is to further assess the effects of image manipulation techniques on improving reading performance.