Age dependence of the average refractive index of the isolated human crystalline lens.

Abstract

We measured the average group refractive index (RI) of 120 isolated lenses from 120 human donors (age: 0.03 to 61 years). The average group RI was calculated from a measurement of the optical thickness of the lens using optical coherence tomography and the apparent window shift of the test chamber caused by the lens. The estimated measurement uncertainty was ±0.004. The group RI at 880 nm was converted to phase RI at 589 nm using the dispersion equation of water and protein. From 2 to 61 years, the mean value of the RI was 1.415 ± 0.002 (group index at 880 nm) and 1.406 ± 0.002 (phase index at 589 nm) independent of age (p = 0.774). Two lenses from donors of age 0.33 and 3 months had significantly lower RI (group index: 1.405 and 1.403; phase index: 1.396 and 1.394). From age 2 to 61, the average lens RI is constant with age within the measurement uncertainty (±0.004).