Age-related changes in porcine lens deformability measured by a digital lens spinner

Abstract

Purpose : The aging of the crystalline lens induces an increase in its rigidity responsible for the loss of accommodation. Research on presbyopia requires the use of a large number of animal lenses that are available without limit in the eyeballs of animals from slaughterhouses. The use of lenses from older animals, which are rarer, seems judicious to understand the physiopathology and to evaluate the effect of new treatments. The measurement of lens deformation at high speed (lens spinning) is one of the methods described to estimate lens rigidity. Objectives: To measure the deformability of the porcine lens as a function of the age of the animal using a new digital lens spinner.

Methods : 65 pairs of porcine globes aged from 6 months to 5 years were obtained from a local slaughterhouse and dissected within 2 h postmortem. We developed an original lens spinner integrating: 1/ a rotating support illuminated by a stroboscopic light synchronized with a CMOS camera; 2/ a software for acquisition and analysis of images in real time. Five parameters were measured on 8 positions of the lens in rotation and averaged. A measurement was performed at 75 rpm inducing no deformation (accommodated state) and then at 1500 rpm (non-accommodated state). The lenses were spun at t0 to estimate the initial comparability between the two lenses of the same animal. They were then stored in culture medium and one of the lenses was heated to 50°C to stiffen it while the other remained at 20°C. A second spin was performed after 6h. A linear mixed-effect model was used for statistical analysis.

Results : The anterior radius of curvature was the most sensitive parameter to deformation. The deformability of the 2 lenses of the same animal were very strongly correlated at t0, regardless of age (R²=0.94, p<0.0001). Elasticity was inversely correlated with age (R²=0.82, p<0.0001). Heating induced a stiffening by a factor of 5 compared to the fresh state, the more so the younger the animals were (p<0.0001). Storage at 20°C did not significantly alter elasticity.

Conclusions : Our lens spinner is suitable for the analysis of large series of lenses. The anterior radius of curvature is the least noisy parameter. This parameter is sensitive enough to measure age-related loss of elasticity in pigs. Heating artificially ages the lens and can be used as a model. The lens of aged pigs can serve as a model of presbyopic lens.

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