AUTOMATIC MEASUREMENT OF REFRACTIVITY

PURPOSE:To always stably minimize the halation quantity of a light detection part regardless of the angle of the astigmatic axis of an eye to be examined without adding a special mechanism, by calculating the point for fixing a target to be measured and the light detection part in an optical axis direction from refractivity in a certain meridian direction and that in the meridian direction crossing said direction at a right angle and setting the same to the position corresponding to average refractivity. CONSTITUTION:When refractivities in two arbitrary meridian directions crossing each other at a right angle are measured, the average value of them becomes average spherical power. Therefore, a target to be measured and the position of a light detection part are moved to the position corresponding to the above mentioned average refractivity to be fixed, and the target to be measured and the light detection part are rotated around an optical axis. By this method, the refractivity of each meridian line is measured and the halation quantity on the light detection part can be minimized and stable measuring accuracy can be always obtained.