Abstract: A cornea-examining instrument includes a plate-shaped examining element of a transparent material, which has at least one light-reflective formation on one end face thereof. The examining element has a bore which extends generally parallel to said one face. A light source, particularly a penlight, has a mounting portion which is accommodated in the bore and through which a beam of light is emitted into the transparent examining element to illuminate the formation so that light reflected therefrom forms an image of the formation on the cornea being examined when a main axis of the examining element intersects the cornea, the shape of the image being indicative of the shape of the cornea. The formation can consist of a continuous groove or a plurality of spaced depressions. When a plurality of the formations is provided, they may be shaped as parallel straight lines symmetrically arranged with respect to the main axis, or as concentric rings.