Using Shack-Hartmann Images to Evaluate Nuclear Cataract

Abstract

Abstract: : Purpose: To continue our assessment of the potential of using Shack/Hartmann wavefront sensing as a tool for objective measurement of ocular scattering. Methods: 66 subjects with LOCS III nuclear opalescence (NO) scores ranging from 0.1 to 4.9 (age 20 - 80 years) and minimal cortical (C<2) and posterior subcapsular (p<2) cataract (with the exception of two: 3.2C 3.1P and 3.4C 0.8P) served as subjects. Shack/Hartmann wavefront images were taken on one eye of each subject. Eyes were dilated. Using shareware image processing developed by the University of Texas Health Science Center in San Antonio (Image Tool www.ddsdx.uthscsa.edu/dig/itdesc.html), each Shack-Hartmann image was analyzed using the object analysis tool. The number of objects detected is related to the point spread function of each lenslet image of the retinal guide star. As the width of each lenslet image increased and began to merge with adjoining lenslet images, the number of objects detected decreased. Data was analyzed by plotting the number of objects detected against LOCS III NO score. Results: The number of objects detected was negatively correlated to LOCS III nuclear opalescence score (r^2 = 0.66). Conclusions: An objective method for measuring early progression of nuclear opalescence using Shack/Hartmann wavefront sensing is viable. Longitudinal studies are needed to determine sensitivity and specificity of the measurement to subtle changes in lenticular scattering properties.

Keywords: cataract • imaging/image analysis: clinical • aging: visual performance