Optical and neural anisotropy in peripheral vision

Area of Science:

• Ophthalmology and Vision Science
• Neuroscience
• Physiological Optics

Background:

• Peripheral retinal optical blur is anisotropic due to aberrations like astigmatism and coma.
• The visual system shows orientation sensitivity anisotropies, including the oblique effect in the fovea and the meridional effect in the periphery.
• The meridional effect describes increased sensitivity to radially-oriented signals in the peripheral retina.

Purpose of the Study:

• To investigate the contributions of optical and neural factors to the meridional effect.
• To quantify optical and neural anisotropy at different retinal eccentricities (0°, 10°, 20°) in the temporal retina.
• To determine if neural orientation sensitivity aligns with optical blur orientation in the periphery.

Main Methods:

• Measured habitual wavefront aberrations to quantify optical anisotropy.
• Used an adaptive optics vision simulator to measure contrast sensitivity (neural anisotropy) while correcting optical aberrations.
• Evaluated participants at 0°, 10°, and 20° eccentricity in the temporal retina.

Main Results:

• Both optical and neural anisotropy increased with retinal eccentricity.
• The ratio of horizontal to vertical optical MTF increased from 0.96 at 0° to 2.15 at 20° eccentricity.
• The ratio of horizontal to vertical contrast sensitivity (with optical correction) increased from 0.99 at 0° to 1.75 at 20° eccentricity.

Conclusions:

• Neural orientation sensitivity aligns with the eye's habitual blur orientation, supporting a neural origin for the meridional effect.
• Findings suggest that peripheral optical quality may influence the development of the meridional effect and emmetropization.
• The study highlights the interplay between optics and neural processing in shaping visual perception in the peripheral retina.