Relation between lens, pupil and ciliary muscle dynamics during accommodation from OCT images

Abstract

Purpose : Knowledge of the lens dynamics during accommodation can provide insight into age-related changes that contribute to presbyopia. However, in addition to age-dependence, there are also significant inter-individual differences in accommodative responses. The goal of this study is to assess the sources of this variability by quantifying the dynamic changes of the lens, pupil, and ciliary muscle during accommodation from OCT images.

Methods : Following an IRB-approved protocol, OCT images of the left eye of 17 subjects (age: 16 to 70 years; mean: 34 ± 16 years) were captured during accommodation in response to a 2D step stimulus using two synchronized Spectral-Domain OCT systems coupled with an accommodative fixation target (Ruggeri et al, BOE, 2016): transscleral OCT for ciliary muscle imaging (1320nm, 13 fps, 7.5 µm axial resolution, 2.5 mm axial range, Thorlabs Telesto, Newton, NJ) and anterior segment OCT for lens and pupil imaging (840 nm, 13 fps, 8 µm axial resolution, 10.4 mm axial range). Images were recorded for 1.54 s before and 4.61 s after the stimulus for a total of 160 images. The time-dependence of lens thickness (LT), pupil diameter (PD), and ciliary muscle thickness (CMT) at mid-point were quantified. CMT-LT, PD-LT, and CMT-PD response diagrams were generated

Results : 8 out of 15 pre-presbyopic subjects responded to the stimulus. In these subjects, there was synchronous movement of the pupil, lens, and ciliary muscle. Figure 1 shows a typical result illustrating the sequence of pupil constriction followed by lens thinning and additional pupil constriction once the lens reached its asymptotic value. For the 7 eyes that did not respond and 2 presbyopes (>55 years), pupil response was inconsistent across subjects, with an increase in PD.

Conclusions : The combination of all 3 measurements (LT, PD, and CMT) is helpful in assessing the source of variability in accommodative responses and the role of the pupil in accommodation dynamics

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Typical accommodative response (31 year old).

 

LT, PD and CMT as a function of age. The different colors represent the 3 different groups, eyes that accommodated, did not accommodate, and presbyopes