Assessing Visual Crowding in Participants With Preperimetric Glaucoma Using Eye Movement and Manual Response...

Crowding is the inability to distinguish objects in the periphery in the presence of clutter. Previous studies showed that crowding is elevated in patients with glaucoma. This could serve as an indicator of the functional visual performance of patients with glaucoma but at present appears too time-consuming and attentionally demanding. We examined visual crowding in individuals with preperimetric glaucoma to compare the potential effectiveness of eye movement-based and manual response paradigms.

We assessed crowding magnitude in 10 participants with preperimetric glaucoma and 10 age-matched controls. Crowding magnitudes were assessed using four different paradigms: a conventional two-alternative forced choice (2AFC) manual, a 2AFC and a six-alternative forced choice (6AFC) eye movement, and a serial search paradigm. All paradigms measured crowding magnitude by comparing participants' orientation discrimination thresholds in isolated and flanked stimulus conditions. Moreover, assessment times and participant preferences were compared across paradigms.

Patients with preperimetric glaucoma exhibited elevated crowding, which was most evident in the manual-response paradigm. The serial search paradigm emerged as the fastest method for assessing thresholds, yet it could not effectively distinguish between glaucoma and control groups. The 6AFC paradigm proved challenging for both groups.

We conclude that patients with preperimetric glaucoma demonstrate heightened binocular visual crowding. This is most effectively demonstrated via the 2AFC manual response paradigm. The additional attentional demand in eye movement paradigms rendered them less effective in the elderly population of the present study.

Our findings underscore both the value and the complexity of efficiently evaluating crowding in elderly participants, including those with preperimetric glaucoma.