Light distortion and spherical aberration for the accommodating and nonaccommodating eye.

Area of Science:

• Ophthalmology
• Optical Engineering
• Vision Science

Background:

• Spherical aberration (SA) is an optical aberration that can affect visual quality.
• Understanding how SA influences light distortion (LD) phenomena like haloes and glare is crucial for visual optics.
• Previous research has explored SA's impact, but specific quantification across varying levels and conditions is needed.

Purpose of the Study:

• To evaluate the impact of induced spherical aberration (SA) on light distortion (LD) phenomena.
• To quantify the relationship between different levels of SA and the severity of visual distortions.
• To assess the influence of pupil size and accommodation on SA-induced light distortion.

Main Methods:

• An experimental device was used to measure light distortion from a point source.
• Eight phase plates inducing SA ranging from +0.300 to -0.300 μm were employed in a double-masked design.
• Measurements were conducted on 10 eyes across five subjects under natural and dilated pupil conditions, with and without cycloplegia.

Main Results:

• Higher positive SA (+0.300 and +0.150 μm) significantly increased all measured distortion parameters, particularly under cycloplegia (disturbance index increased from 14.86% to 57.98%).
• Negative SA did not increase LD and, in some cases, decreased distortion compared to the control.
• Pupillary dilation and cycloplegia exacerbated LD with increasing positive SA, while accommodation and pupillary constriction mitigated these effects.

Conclusions:

• Positive spherical aberration significantly degrades optical quality, leading to increased light distortion.
• Negative spherical aberration appears to have a neutral or even beneficial effect on light distortion.
• The eye's natural mechanisms, such as accommodation and pupillary constriction, can compensate for induced optical aberrations and preserve visual quality.