Visual test of Listing's law during vergence

Area of Science:

• Ophthalmology
• Neuroscience
• Biomechanics

Background:

• Understanding ocular motor control is crucial for diagnosing and treating visual disorders.
• Listing's Law describes the rotational behavior of the eye, but its precise application during vergence remains debated.
• Previous research using search-coil methods provided insights into eye movements, necessitating further investigation with alternative methods.

Purpose of the Study:

• To quantify the rotational changes in Listing's plane as a function of vergence angle.
• To investigate the torsional disparity of visual targets during different vergence tasks.
• To compare visual test results with previous search-coil measurements regarding inter-eye Listing's plane angles.

Main Methods:

• A simple visual test was developed to measure Listing's plane rotation.
• Measurements were taken during vergence on a near target, fixed prisms, and rotating prisms.
• The test assessed the elevation-dependent torsional disparity of horizontal and vertical lines.

Main Results:

• The study successfully measured Listing's plane rotation relative to the vergence angle.
• Torsional disparity was quantified across different vergence conditions and prism manipulations.
• Results indicated that the angle between the two eyes' Listing's planes is less than the vergence angle.

Conclusions:

• The visual test provides a viable method for assessing Listing's plane rotation.
• Findings support previous search-coil data, suggesting a specific relationship between Listing's planes and vergence.
• The results contribute to a refined understanding of binocular eye movement control.