Spherical aberration of the crystalline lens measured in-vitro using an LRT-OCT system (Conference Presentation)

Abstract

Anatomical changes of the growing crystalline lens influence its refractive development, including power and spherical aberration. We have recently developed a new instrument that characterizes both the optical and biometric properties of the lens in-vitro by merging Ray-Tracing Aberrometry (RTA) with three-dimensional OCT imaging. In this abstract, we describe the application of the RTA to the measurement of lens spherical aberration. Experiments were performed on 54 isolated human lenses (age: 0.25 to 56 years). The system was programmed to sequentially deliver the probing beam through the lens using a raster scan pattern of 13 × 13 transversal positions spaced 0.5 mm apart. Exit rays were imaged after exiting the tissue chamber at 9 different axial positions (ΔZ = 0 mm to 8 mm) in 1 mm intervals. A total of 1,521 spot images were acquired per lens. All data was automatically analyzed using custom software we developed in MATLAB. Exit ray slopes over a 6 mm pupil were used to determine Zernike wavefront coefficients up to the sixth order. The 4th order Zernike coefficient Z[4,0] was used to measure primary spherical aberration (SA). The results suggest that spherical aberration of the growing lens becomes more negative before adulthood and less negative after around age 30. The data is consistent with results from in-vivo studies that suggest the lens spherical aberration becomes less negative in older lenses (>30 years).