Oculomotor Metrics Improve Following Eccentric Retinal Locus Training

Fixation stability and saccadic precision can improve with training after creating a preferred retinal locus (PRL) in healthy individuals through simulated central vision loss, according to research published inVision Research. These findings suggest that low vision interventions should address both fixation stability and saccadic precision. 

Researchers enrolled 40 normally-sighted participants (30 women; mean age, 24.8 years) in a study to assess fixation and saccadic metrics following vision recognition tasks designed to create a new PRL. Patients viewed visual computer stimuli on a screen while fixated and secured with a chin strap while an infrared video-based eye tracker recorded saccades and fixations. The display simulated a scotoma and occluded central vision. Participants completed a total of 12 trials during which they performed face, object and word recognition tasks.    

The team assessed a total of 6 oculomotor metrics, and all 6 significantly improved from trial 1 to trial 12. The spatial distribution of the first saccades across trials, distribution of first saccades that did not obscure the target, interval between target appearance and end point of the first useful fixation, and eye position dispersion within trials after the first saccade all experienced significant decreases (all P <.0001), according to the report. Saccadic precision and the percentage of useful trials increased (both P <.01).

Mean accuracy for the letter, object and word recognition tasks improved by 19.78%, 18.38% and 20.88%, respectively, from trial 1 to trial 12.

“[W]e have demonstrated that saccadic precision has a moderate association with accuracy and can be learned almost simultaneously with fixation stability when training utilizes a method that requires more than just static eye gaze,” according to the researchers. “Given the importance of saccadic eye movements in reading and visual search, clinical interventions that focus on fixation stability should also include opportunities for developing saccadic precision to improve performance.”

This research was limited by a relatively small number of participants.