ARRANGEMENT FOR MEASURING THE OPTICAL QUALITY OF THE ANTERIOR SEGMENT OF THE EYE AND GRATING ELEMENT THEREFOR

摘要

An arrangement for measuring the optical quality of the anterior segment of the human eye has a source of illumination, a grating element marked with a novel pattern, a camera and a processing means. The grating element pattern consists of a series of parallel lines which are made up of respective numbers of alternate light and dark dashes, the respective numbers becoming greater going from one end of the series to the other. In use, the source of illumination projects a light through the grating element towards the eye to be examined, the camera forms an image corresponding to the image of the grating element pattern reflected from the posterior surface of the eye's lens and the processing means carries out processing on the camera image such as to provide a measure of the anterior-segment optical quality. Preferably the processing stage measures quality using a modulation transfer function of the system.