Changes in the objective amplitude of accommodation with pupil size

Area of Science:

• Ophthalmology
• Vision Science
• Optometry

Background:

• Pupil size naturally changes with ambient lighting.
• Accommodation, the eye's ability to change focus, is crucial for clear vision.
• Previous studies suggest pupil size influences visual performance, but objective measures of accommodation are less understood.

Purpose of the Study:

• To objectively measure the effect of pupil size on the amplitude of accommodation (AA).
• To investigate how ambient lighting conditions, which alter pupil size, impact objective AA measurements.

Main Methods:

• Wavefront aberrometry was used to objectively compute AA in 15 eyes.
• Measurements were taken under low and high ambient light conditions.
• AA was calculated considering paraxial rays (paraxial AA) and spherical aberration (minRMS AA).

Main Results:

• Mean pupil diameter decreased significantly with increased light.
• Objective AA (both paraxial and minRMS) was significantly greater in high light (smaller pupils) compared to low light (larger pupils).
• Accommodative miosis (pupil constriction during accommodation) was more pronounced in low light.

Conclusions:

• Ambient lighting significantly influences objective AA, primarily due to changes in pupil size.
• The reduction in AA with larger pupils is mainly attributed to decreased paraxial accommodation.
• Spherical aberration changes with pupil dilation play a lesser role in this observed effect.