What we don’t know about eccentric viewing
The link between central scotomas, Troxler fading, and preferred retinal locus
Every clinician who has worked with patients with central scotomas has observed the difficulty those patients experience. Not only have they lost the ability to resolve fine detail, they also see nothing “straight ahead”. The resulting behaviour, most commonly called “eccentric viewing”, typically involves the development of a “pseudofovea”, or a preferred retinal locus (PRL). The use of a PRL is primarily an eye movement control issue: the individual must be able to place an object of interest on a particular fundus location. In addition to eye position control, however, successful use of an eccentric location must involve much more than just that. As Deruaz and colleagues have pointed out in this issue of BJO (p 461), higher level sensory processes are likely to be involved. …
