Horizontal fusional amplitudes after adaptation to prism

Area of Science:

• Ophthalmology and Vision Science
• Neuroscience
• Biophysics

Background:

• Understanding vergence adaptation is crucial for visual perception and eye movement control.
• Current models propose distinct fast and slow mechanisms for fusional vergence.

Purpose of the Study:

• To investigate the effects of prism adaptation on horizontal fusional limits and lateral phorias.
• To evaluate the impact of vergence adaptation on fusional amplitudes.

Main Methods:

• Subjective measurement of horizontal fusional limits and lateral phorias in five healthy subjects.
• Adaptation to increments of base-in and base-out prism.

Main Results:

• Both lateral phorias and horizontal fusional limits adapted approximately to the magnitude of the introduced prism.
• Fusional amplitudes showed minimal change with vergence adaptation, except at high prism values.

Conclusions:

• Findings support models of disparity vergence with independent fast and slow fusional vergence mechanisms.
• Each vergence mechanism appears to have its own saturation limit, influencing adaptation effects.