High-speed dynamic biometry of the lens-pupil response during accommodation

Abstract

Purpose : The optical accommodative response is a dynamic process that involves changes in lens shape and pupil diameter. The goal of this study is to analyze the dynamics of the lens and pupil during accommodation.

Methods : Using a custom-built high-speed swept-source OCT (SS-OCT) system, we imaged the anterior segment of one randomly selected eye from 4 young subjects (age: 20 to 26 years; MSE: -0.82 ± 1.75 D; 0 to -3.38 D) and 2 pre-presbyopes (age: 40 and 45 years; MSE: -0.63 and -4.38 D). Images were recorded at 100 frames/sec for 10 s (1000 frames) during the accommodative response to a step stimulus presented by a fixation target 3 sec after the beginning of the acquisition. In young subjects, accommodative responses were acquired for step stimulus amplitudes of 1 to 5 D in 1D steps and for maximum accommodation if greater than 5 D. In pre-presbyopes, accommodative responses were acquired for a step stimulus set to the subject’s maximum accommodation. Lens thickness and pupil diameter were quantified in each frame using a custom-made MATLAB application. We measured the velocity (mm/s) at the beginning of the accommodation response, the latency (s), the pupil diameter (mm), and the change in lens thickness (mm).

Results : For the response at maximal accommodation, the pupil diameter and the lens thickness changed on average by 1.29 ± 0.77 mm and 0.35 ± 0.08 mm respectively in young subjects and 1.61 ± 1.18 mm and 0.10 ± 0.02 mm in pre-presbyopes. The dynamic response showed that the accommodation response begins with a change in lens thickness at 3.34 sec on average and that pupil constriction begins on average at 3.58 sec, shortly before the end of the lens thickness change (Fig. 1). There is no difference in latency or velocity among the young subjects for the different accommodation stimuli (ANOVA, p = 0.85 and p = 0.72, respectively).

Conclusions : The changes in pupil diameter and lens thickness during dynamic accommodation are asynchronous. The change in lens thickness precedes the change in pupil diameter. High-speed dynamic biometry enables quantification of the lens-pupil response during accommodation.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.