Abstract
Purpose :
The aim of this study is to examine the effectiveness of the accommodative response of the adult human eye when subject to either parafoveal or perifoveal stimuli. Understanding the non-foveal accommodative response is of special relevance as it provides important insight into mechanisms that are likely linked to emmetropization and equally to myopia progression.
Methods :
A near-IR laser diode (850 nm) and a fast Hartmann-Shack wavefront sensor (Thorlabs) were used to capture ocular aberrations up to the 4th Zernike order at 20 Hz framerate. The natural pupil was constricted to 3 mm by a pupil-conjugated iris. Subjects viewed monocularly green annular targets with diameter corresponding to visual fields from 2° to 16° (in 2° increments) placed at 1-meter distance on a computer screen. A current-driven tuneable lens (Optotune) placed in a conjugate pupil plane generated rapid random step defocus changes every 10 sec. within the accommodation range of each subject. A total of 6 subjects (3 emmetropes and 3 myopes) in the age range of 23 – 34 years and with normal vision were measured and their accommodative response recorded while instructed to gaze towards the center of the visual target.
Results :
At 2° and 4° eccentricities, all subjects could compensate the induced defocus in the range of 90% - 100%. At eccentricities of 6°, 8°, 10°, and 12° the accommodative response reduced gradually from 70% to 15%. Beyond 14° eccentricity the accommodative response was essentially absent. Also, the accommodative response time increased with eccentricity to beyond 1 sec at 10°.
Conclusions :
The findings show that the young adult eye can accommodate and de-accommodate with parafoveal and perifoveal vision although with reduced efficiency. The accommodative response gradually diminished with eccentricity and was largely absent beyond 14° eccentricity. No significant differences were found in the accommodative response between emmetropes and myopes.
This is a 2020 ARVO Annual Meeting abstract.