On and off axis confocal double pass measurements of the point spread function in the human eye

The confocal principle was applied to double pass method to measure the point spread function (PSF) of the human eye and an artificial eye, and to improve the ratio of signal to noise of retinal images. The double-pass PSFs of four human eyes on and off the optical axis of the eyes were measured. The off-axis double pass PSF in the human eye along vertical and horizontal direction is asymmetrical. When the subject looks left on the horizontal off axis, the PSF appears right of the optical axis of the subject eye. When the subject looks right the PSF is located left of the optical axis. The location of the PSF on the vertical off axis appears above the optical axis when the subject looks up. When the subject looks down the double pass PSF is located below the axis. The PSFs of the human eye recorded at varying off-axis angles are presented. Asymmetrical results suggest a more dynamic process in the optical system of the eye perhaps driven by the complicated outer or inner ocular structure.