Simulated retinal images of Landolt rings in human eyes including asymmetric aberrations on the point spread function analysis system

We newly developed a Point Spread Function Analysis System (PSFAS) to study the optical system of the human eye. In this system, an infrared point light source is projected onto the subject's eye and the reflected image at the retina is captured by the charge coupled device (CCD) (i.e., double-pass formula). The single-pass modulation transfer function (MTF) is calculated from the captured image with equal sized apertures of the entrance and exit pupils, and the phase transfer function (PTF) is calculated from the captured image with unequal sized apertures of them. The optical transfer function (OTF) is deduced from this MTF and PTF, then retinal images can be simulated with both this OTF and the original charts. The smaller aperture of the incident ray is determined so as to give a diffraction limit, then the simulated retinal images include the information of asymmetric aberrations. The simulated retinal images of the Landolt's rings were compared with subjective sensations in the same subject with keratoconus. The PSFAS can objectively evaluate the characteristics of the human optical system and therefore is very useful in an ophthalmology clinic setting.