REAL SIGNIFICANCE OF CENTERING A CONTACT LENS

The prevailing method among physicians when centering a contact lens has been to center the cornea of the lens with the cornea of the eye. The cosmetic appearance of the lens is best when the cornea of the lens is thus centered with, and in a way superimposed on, the cornea of the eye. But the optical effect of such centering may or may not be the best. Pronounced displacement of the lens cornea with reference to the cornea of the eye will practically always impair vision. But a slight displacement may definitely improve vision, sometimes considerably so, after the lens has been worn for some time. To understand what happens, one must consider the optical system of the eye alone and that when a contact lens is worn. The two components of the optical system of the eye are the cornea and the crystalline lens. The latter, as has