Quantification of Synchronized Lens and Pupil Dynamics During Accommodation

Abstract

Purpose : Presbyopia is driven by a loss of lens responsiveness, but the effect of lens changes may be diminished by adaptive changes such as increased "pseudoaccommodation" through changes in pupil size. We explore the role of the pupil by quantifying lens and pupil behavior during accommodation in individuals from a young to pre-presbyopic population.

Methods : The left eyes from 9 subjects were imaged during responses to step accommodation stimuli using a custom-built extended depth OCT system (Ruggeri et al, Biomed Opt Express 3:1506-1520; 2012) (12,500 A-lines/s, 8 µm axial resolution, 13.5 mm imaging depth). 7 subjects (22-39 y/o) were imaged at stimuli of 2 and 4D and 2 (45 and 46 y/o) at 2D only. Cross-sectional images were acquired at 400 A-lines/frame and 13 frames/s producing dynamic datasets of the accommodative response of the anterior segment from anterior cornea to posterior lens. Lens thickness (LT) and pupil diameter (PD) were determined for each frame through automatic segmentation (Figure 1). Changes in LT and PD were determined as the difference between the average LT and PD for the last and first 10 images, normalized by stimulus, and then averaged across stimulus levels. To quantify the relation between the time course of LT and PD change in an individual, the time-points at which PD and LT reached their steady state values, defined as the values of PD and LT averaged over the last 10 images, respectively, were calculated, and the difference in time between the two time-points (Δt) was determined.

Results : As shown in Figure 2, LT change during accommodation did not differ significantly with age (p = 0.32) with a mean LT change/D of 0.055 mm/D, whereas the magnitude of PD change during accommodation increased with age (p = 0.01; PD change/D = -0.018 mm * Age + 0.220 mm). Δt appeared to increase with age in 2D trials, but the relationship did not reach significance (p = 0.10).

Conclusions : The age-related increase in PD change manifested in a longer response of the pupil relative to the lens with increasing age, suggesting the pupil may be involved in compensating for the loss of lens accommodation with age.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.