Rehabilitation of hemianopia

Homonymous hemianopia is the commonest form of acquired homonymous visual field defect; the usual causes are stroke, head injury and intracranial tumours. This impairment can affect a variety of cognitive visual functions, including visual search, safe navigation through changing environments and reading. A number of rehabilitative techniques have been tried with varying degrees of success. They broadly fall into three main groups: optical therapies, in which the damaged visual field is brought into view by the use of optical devices; eye movement-based therapies, in which the damaged visual field is more effectively sampled with compensatory or adaptive eye movements; and visual field restitution therapies, in which vision in the damaged field is itself improved. These techniques all rely on mass practice. This review provides an up-to-date summary of these approaches.

All of the three main approaches to rehabilitation of homonymous visual field defect have been pursued in recent years and all appear capable of providing a moderate amount of 'real-world' improvement to patients. Controversy still reigns over the mechanism of action of all but the optical methods. Patients have to practice for many hours to feel the benefit of all of these techniques, with the eye movement-based therapies requiring the least amount of exposure.

The evidence base for these types of behavioural therapy is getting stronger all the time. Future studies that take on the difficult task of controlling for placebo effects will allow patients' subjective ratings of success to be used as a convincing outcome measure. Without doubt, the literature would also benefit from bigger studies that include more patients; however, one could argue that given the clear negative effect that homonymous visual field defect has on patients' lives, these therapies should be more widely available already.