Retinal-image quality. (
A) MTFs with native optical aberrations. The MTF of an eye with a 6-mm pupil and only limited by diffraction is represented by the
black curve. The blue curve indicates the MTF (averaged across orientation) for the native optics of our four emmetropic participants. Boxes indicate the 25th and 75th percentiles. Error bars are the maximum and minimum values. The other curves are the MTFs for each keratoconus patient (
Table); different colors represent different patients (see legend). (
B) Optical degradation. We quantified optical degradation in each keratoconus patient by computing the ratio of the median emmetropic MTFs divided by the MTF of each keratoconus patient. Values greater than 1 indicate poorer quality in the keratoconus patient than in the median emmetrope. Best fits to those ratios are given by: 0.025
sf + 1.94 (mild keratoconus), 0.25
sf + 3.91 and 0.015
sf + 2.74 (moderate), and 0.13
sf + 10.88 (severe), where
sf represents spatial frequency. (
C)
Left: Corresponding power spectra. One hundred randomly chosen images from the McGill image database
23 were convolved with the point spread functions (PSFs) of the participants to simulate their retinal images with native optics. The mean radially averaged power from the 100 images is plotted here. The
blue shaded area represents the range across the emmetropic eyes. Other colors are the keratoconus patients (see legend).
Right: Polychromatic simulations of the retinal images for a 6-mm pupil. (
D) Radially averaged MTFs during adaptive optics correction. The improvement in the MTF during correction is given in
Supplementary Figure S1. (
E) Corresponding power spectra during adaptive optics correction, computed as in (
C), except now using the PSFs during correction.