Bin Yang¹, Michele Rucci¹; ¹University of Rochester

While eye movements and their visual functions have been extensively studied, less attention has been paid to the motion of the lens inside the eye. Here, we used digital dual Purkinje imaging to measure lens motion in the human eye and investigate its possible consequences for vision. Our results show that lens motion alternates between saccade-driven wobbles and fixational high-frequency (~75 Hz) oscillations. We observed a decreased oscillation frequency of the lens when subjects (N=5) accommodated to near distances, presumably due to the lower tension in the suspensory ligaments. We also found a strong negative correlation between peak lens oscillation frequency and age (N=19), consistent with the lens losing flexibility and yielding a lower tension with aging. A model of the lens as a damped harmonic oscillator driven by either saccades or fixational eye jitter indicates that lens oscillations amplify fixational motion by approximately a factor of three and that the resonant frequency of lens wobble is about half the fixation frequency (N=12). An optical model of the eye and analysis of data previously collected with an Adaptive Optics Scanning Laser Ophthalmoscope (N=6) confirm that the fixational lens oscillations cause minimal image motion on the retina. However, saccade-driven lens wobbles result in nonnegligible retinal motion, yielding luminance modulations with approximately uniform power across a broad range of spatial frequencies during viewing of natural scenes. In sum, our results suggest that, driven by the unsteady eye, the lens is in constant motion, oscillating at high frequency unless interrupted by saccade-associated sharp wobbles, which affect visual input signals to the retina.

Acknowledgements: NIH EY18363