Abstract
Purpose :
People with central vision loss (CVL) often adopt a peripheral preferred retinal locus (PRL) to fixate targets in the visual scene. The PRL is usually measured with simple fixation tasks. Previous studies have shown that some patients use different PRLs for different viewing conditions or tasks, but it remains unclear whether the fixation PRL (fPRL) is used in reading, which requires frequent saccadic eye movements. We previously reported a method for identifying the preferred retinal location used for reading in patients with central vision loss (Fidanci et al., ARVO 2023). Here, we used this method to test if this reading PRL is in the same location as the fixation PRL.
Methods :
We tested 10 participants with CVL [7 AMD and 3 others]. We also tested 10 normally sighted controls for whom the fPRL was expected to be the fovea. Binocular eye positions were recorded via an eye tracker while reading three-line sentences from the MNRead charts. A 5-point calibration task, fixating successively displayed points, allowed tracking of the fPRL. Reading was interrupted at randomly determined times by a blank screen. Participants then reported the word being read when the interruption occurred, assumed to be at or close to the reading PRL. We computed the distance between the reported word and the word at the fPRL (as indicated by the eye tracker).
Results :
In both groups, eight of ten participants reported the word at the fPRL most commonly, on average, in 57.02% (CVL) and 58.53% (control) of trials. This pattern would be expected if reading uses the fPRL. Two control and one CVL participant most frequently reported one word to the right of the fPRL, likely representing use of peripheral "preview” in reading. Another CVL participant reported one word to the left of the fPRL. This participant also had an unusually high rate of leftward saccades, which could indicate that processing of a word continued after the eyes shifted forward. All participants' fPRLs were aligned vertically with the line of text where the reported word was located, with minimal vertical offset.
Conclusions :
In all of our sample of CVL participants, the word reported as being read was at the fPRL, or close to it. These results suggest predominant use of the fPRL in reading tasks.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.