1. A specular microscope having wide field scanning for the examination under magnification of a selected generally planar area within the cornea of an eye, said microscope comprising a lens system including a converging lens and an objective lens, observation means, opaque masking means positioned in a plane normal to the optical axis of said microscope between said lens system and said observation means, said masking means including first and second spaced parallel linear slit portions extending therethrough and disposed at opposite sides of said optical axis, means for oscillating said masking means in said plane in a direction normal to the length of said slit portions at a desired rate, illuminating means for directing a beam of light through said first slit portion, said converging lens and said objective lens, to illuminate a narrow elongate area within the cornea of an eye positioned behind said objective lens on one side of said masking means, said observations means being positioned on the other side of said masking means to receive light reflected from said elongate area and passing through said objective and converging lenses and said second slit portion in the direction of said optical axis of said microscope.