Identifying the Preferred Retinal Locus for Reading

Abstract

People with central vision loss (CVL) often adopt a specific retinal location, known as the preferred retinal locus (PRL), outside of the region of loss to fixate targets in the visual field. The PRL is most often measured using simple fixation tasks. It has been reported that this location on the retina, also known as fixational PRL (fPRL), does not necessarily correspond to the retinal locus used in other tasks. However, it has been challenging to measure the PRL while observers are reading, a task involving frequent eye movements. This thesis presents a study investigating whether the attended location during reading in CVL participants corresponds to the fixation PRL. In our study, we developed a method to determine the retinal area engaged during fixations in reading. We validated this method for identifying the retinal location attended to during reading with ten control participants. We then used this method for assessing reading PRLs in three patients with central vision loss. Results showed that while two of the CVL patients used the fixational PRL location in reading, another patient with CVL appeared to use a different retinal location in reading. These findings help us to understand the practical use of PRL locations across tasks, especially for uncovering whether and how often the fixational PRL corresponds to the PRL used for reading.