Abstract
The progressive loss of accommodation of the eye, called presbyopia, affects people with age and can result in a complete loss of accommodation by about age 55 years. It is generally accepted that presbyopia is due to an increase in stiffness of the lens. With increasing age, the stiffness of the crystalline lens nucleus increases faster than that of the cortex. During accommodation, the deformation of different parts of the crystalline lens is different and likely changes with age. However, a direct observation of crystalline lens deformation and strain distribution is difficult because although imaging methods such as OCT or Scheimpflug imaging can distinguish cortex and nucleus, they cannot determine their regional deformation. Here, patterns of laser-induced microbubbles were created in gelatin phantoms and different parts of excised animal crystalline lenses and their displacements in response to external deformation were tracked by ultrasound imaging. In the animal lenses, the deformation of the lens cortex was greater than that of nucleus and this regional difference is greater for a 27-month-old bovine lens than for a 6-month-old porcine lens. This approach enables visualization of localized, regional deformation of crystalline lenses and, if applied to lenses from animal species that undergo accommodation, may help to understand the mechanisms of accommodation and presbyopia, improve diagnostics, and, potentially, aid in the development of new methods of lens modifying presbyopia treatments.
