Abstract
Purpose :
During accommodation, lens shape changes produce changes in the axial refractive index distribution which may contribute to the change in lens power. The goal of this study is to quantify accommodative changes in the average axial refractive index.
Methods :
33 whole globes from 29 Cynomolgus monkeys (Macaca fascicularis, ages: 4.1–17.9 years; post-mortem time: 15.9±15.7 hours) were dissected and mounted into a tissue chamber submerged in Dulbecco's Modified Eagle's Medium (DMEM) within a lens stretcher (Ehrmann et al., 2008). Experiments were performed by stretching the tissue radially outward from 0 mm (unstretched) to 2.5 mm (fully stretched). Time-domain optical coherence tomography (OCT) imaging was used to acquire cross-sectional images of the lens with stretching. ImageJ was used to determine the axial pixel coordinates of the anterior (AL) and posterior (PL) lens surfaces, the undistorted tissue chamber wall (W1), and the distorted wall below the lens (W2) from the OCT images. These coordinates were used to calculate the average refractive index of the lens at the unstretched and fully stretched positions (Uhlhorn et al., 2008). (Figure 1)
Results :
On average, the refractive index was 1.417 ± 0.002 for the unstretched (accommodated) lens and 1.416 ± 0.002 for the fully stretched (relaxed) lens. There was no statistically significant change in refractive index with lens stretching (p-value = 0.10) or with age (p-value = 0.17). (Figure 2)
Conclusions :
The average refractive index of the monkey lens remains constant with accommodation and does not show a significant age-dependence.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.