Longitudinal changes in thickness of the aging human lens measured with OCT

Abstract

Purpose : Continuous growth of the lens in adulthood produces age-related increase in lens thickness and curvature which impact the lens power. Previous studies on biometry of the aging lens are cross-sectional. In this study, we quantify the longitudinal changes in thickness of the aging human lens using OCT.

Methods : This retrospective study evaluates lens biometry data from 10 eyes of 5 subjects (Age at the initial visit: 21, 26, 30, 34 and 42 years) acquired with a custom-built OCT system at variable intervals between sessions (6.5 months on average) over about 10 years. The system combines a fixation target with adjustable vergence and a SD-OCT system that enables imaging from the anterior corneal surface to the posterior crystalline lens (Ruggeri et al, Biomed Opt Exp 2012). Each OCT dataset consists of at least three images of the lens sequentially acquired across the horizontal meridian of the eye without repositioning the system. All images were acquired with the fixation target adjusted to a vergence of 0 D (distance). For each eye and time point, three consecutive OCT images extracted from the same dataset were processed to manually select the lens surface boundaries and calculate the lens thickness. The processing relies on peak detection of the average reflectivity profile of the lens over the 0.5 mm zone. The lens thickness was obtained from the optical path length assuming a uniform refractive index for the lens (n = 1.415). The average lens thickness across the three measurements was then calculated. Linear regression was used to describe the change in average lens thickness with age. All eyes were included in the analysis.

Results : As expected, the lens increases in thickness with age (Figure A) in all subjects (Age 21: R²=0.704, P=0.002; Age 26: R²=0.9996, P=0.039; Age 30, R²=0.939, P<0.001; Age 34: R²=0.973, P<0.001 and Age 42, R²=0.960, P=0.001) of on average 28 µm/year (range 21 to 42 µm/year) (Figure B), which is consistent with findings from cross-sectional studies using Scheimpflug imaging (Dubbelman et al, Optom Vis Sci 2001). The increase in lens thickness was on average greater in the two oldest subjects (36 vs 21 µm/year), suggesting the lens grows faster in incipient presbyopia (Figure A).

Conclusions : We used OCT to quantify the longitudinal increase in crystalline lens thickness over 10 years in 5 adult subjects. The preliminary data suggest a faster growth of the lens in incipient presbyopia.

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