Speed of Ultrasound Gradient Across the Equatorial Profile of the Isolated Human Crystalline Lens

Abstract

Purpose: : To determine if speed of sound varies across the equatorial profile of the lens.

Methods: : Speed of sound was measured in human crystalline lenses (n=3, age = 28, 52 and 67 years) with a 35-MHz transducer (Sonomed VuMax UBM) using a Time-of-Flight method. The lenses were placed in a temperature-controlled cell filled with DMEM at 37°C. Three measurements were made at the center of the lens. The transducer was linearly translated in steps of 0.1mm from equator to equator to measure speed across the equatorial profile.

Results: : Speed of sound at the center of the lens was 1687.7 ± 10.3 m/s for the 28 y/o lens, 1680.4 ± 7.3 m/s for the 52 y/o lens and 1686.7 ± 7.3 m/s for the 67 y/o lens. Speed profiles were compared to refractive index profiles across the diameter of similar aged lenses (Jones, et al., 2005) and found to be similar. There was a larger variation of the speed of sound across the sagittal profile in the young lens compared to the older lenses.

Conclusions: : Speed profiles are similar to refractive index profiles obtained using MRI. Results from speed of sound measurements are consistent with lens compaction and with the formation of a nuclear protein plateau.Support: NIH Grants 2R01EY14225, P30EY14801 (Center Grant); the Florida Lions Eye Bank; an unrestricted grant from Research to Prevent Blindness;Australian Federal Government CRC Scheme through the Vision Cooperative Research Centre; Henri and Flore Lesieur Foundation (JMP).

Keywords: accommodation • imaging/image analysis: non-clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)