MONOCHROMATIC ABERRATIONS AND POINT-SPREAD FUNCTIONS OF THE HUMAN EYEACROSS THE VISUAL-FIELD

The monochromatic aberrations of the human eye along the temporal meri dian are studied by a novel laser ray-tracing method. It consists of d elivering a narrow laser pencil into the eye through a given point on the pupil and recording the aerial image of the retinal spot with a CC D camera. The relative displacement of this image is proportional to t he geometrical aberration of the ray (laser pencil) at the retina. We scanned the pupils of four observers in steps of 1 mm (effective diame ter, 6.7 mm) and for five field angles (0 degrees, 5 degrees, 10 degre es, 20 degrees, and 40 degrees). In addition, the aerial image for eac h chief ray is a low-pass-filtered version of the retinal point-spread function corresponding to a fully dilated pupil. The resulting spot d iagrams, displaying the distribution of ray aberrations, are highly co rrelated with these point-spread functions. We have estimated the wave -front error by fitting Zernike polynomials (up to the fifth order). D espite the large variation found among observers, the overall rms wave -front error is relatively homogeneous. At the fovea, the average rms value was 1.49 mu m when the second-order terms (defocus and astigmati sm) were considered; this was reduced to 0.45 mu m when the second-ord er terms were ignored. The rms values increase slowly, in a roughly li near fashion with eccentricity, such that at 40 degrees they are appro ximately double. These results are consistent with previous findings o n the off-axis optical quality of the eye. (C) 1998 Optical Society of America.