The wide-angle point spread function of the human eye reconstructed by a new optical method

The point spread function (PSF) of the human eye spans over a wide angular distribution where the central part is associated mostly to optical aberrations while the peripheral zones are associated to light scattering. There is a plethora of optical methods for the direct and indirect measurements of the central part of the PSF as a result of monochromatic and polychromatic aberrations. The impact of the spatial characteristics of this central part of the PSF on the retinal image quality and visual function has been extensively analyzed and documented both by optical and psychophysical methods. However, the more peripheral areas of the PSF in the living human eye, ranging from about 1 to 10 degrees of eccentricity, have been investigated only psychophysically. We report here a new optical method for the accurate reconstruction of the wide-angle PSF in the living human eye up to 8 degrees. The methodology consists of projecting disks of uniform radiance on the retina, recording the images after reflection and double pass through the eye's optics and performing a proper analysis of the images. Examples of application of the technique in real eyes with different amount of scatter artificially induced are presented. This procedure allows the direct, accurate, and in vivo measurement of the effect of intraocular scattering and may be a step toward the comprehensive optical evaluation of the optics of the living human eye.