Visual Crowding Reveals Field- and Axis-Specific Cortical Miswiring After Long-Term Axial Misalignment in Strabismic...

Area of Science:

• Neuroscience
• Ophthalmology
• Visual Perception

Background:

• Squint (strabismus) can alter brain structure and function in early visual areas.
• Visual crowding, a bottleneck in object recognition, is a sensitive index of cortical organization.

Purpose of the Study:

• To investigate if strabismic eyes without amblyopia exhibit increased visual crowding.
• To determine if visual crowding is linked to cortical organization in strabismus.

Main Methods:

• Gaze-contingent display with real-time eye tracking was used.
• Visual crowding was assessed in patients with esotropia and exotropia but no amblyopia, and in age-matched controls.

Main Results:

• Patients with strabismus without amblyopia showed significantly increased critical spacing (visual crowding).
• This crowding exhibited nasotemporal asymmetry along the radial axis, varying with strabismus type (exotropia: temporal crowding; esotropia: nasal crowding).
• Crowding magnitude correlated with strabismus duration and degree.

Conclusions:

• Visual crowding is a valid psychophysical index for cortical organization in strabismus.
• Strabismus without amblyopia leads to greater peripheral visual crowding with specific nasotemporal asymmetry.
• Findings suggest hemifield- and axis-specific cortical miswiring in object recognition due to ocular misalignment.