opticiancertif

The amount of myopia, hyperopia or astigmatism. An error in refraction of the eye. An optical defect in an unaccommodating eye in which parallel light rays do not focus sharply on the retina.

A test to determine the refractive state of the eye, and the best corrective lenses required to aid in clear vision. A series of lenses in graded powers are offered to determine which provide sharpest, clearest vision.

Central opening of the iris through which rays of light enter the eye. The diameter depends on ambient light. An opening in the center of the iris, of variable sizes, that regulates the amount of light that enters the eye.