When I first heard of hemianopic alexia I thought for a wild moment it referred to a person (there is a name Alexia)! But it actually means problems with reading caused by homonymous hemianopia — loss of peripheral vision on the same side of both eyes. This condition is common amongst people who have survived strokes, about one in five of whom are affected. Suddenlynot being able to read can obviously have devastating effects on daily life as well as threatening ones livilihood.
Homonymous hemianopia causes reading difficulty because the person affected either has trouble locating the beginning of each line of text — if it is the left visual field that is affected — or locating the end of the line, if it is the right visual field. The person may also experience difficulty because the blind area can block the end of long words.
Using a marker of some kind, such as a ruler or a post-it note can help locate the beginning or end of the line, and there are also reports of patients who benefited from turning the text through 90° and reading vertically upwards. Another approach is ‘last letter cancellation therapy’, in which the patient practices looking at the ends of words rather than their beginnings, by crossing off the last letter of each word with a red pen.
Now a new web-based approach seems very promising. The Read-Right project at the UCL Institute of Neurology claims improvements of up to 39% after 15 hours of practice with a new therapy.
According to the Read-Right website, the reason why right homonymous hemianopia slows down reading is not just that the patient can’t locate the end of the line. It seems that when reading we make a series of eye movements and we need our right peripheral vision to plan these. When this peripheral vision is lost our eye movements become inefficient and reading is slowed down.
The Read-Right therapy works by having patients read moving text on their computer screen, although the mechanism by which it improves reading is not yet completely understood.
A sister project, Eye-Search, also at UCL, helps stroke survivors locate objects they have put down and can’t find again. This has been something I’ve had a lot of problems with myself and I have to be careful that if I put down my phone or glasses I remember where they are.
Both these projects have been funded by the Stroke Association. You can read more here.
Have I signed up? I certainly have and I’ll report in a subsequent post.