The Marco Keratometer I is a one position instrument for objectively measuring corneal curvature. By simply rotating the Keratometer until a major axis is located, curvatures in both major and minor meridians can readily be measured. The Marco Keratometer assures objective accuracy in such measurements as well as in the fitting of contact lenses. Manufactured with brass and stainless steel moving parts for durability, the Marco Keratometer incorporates such other features as precision objectives, achromatic prisms, and uniform diffuse illumination. Dual reading knobs measure in both millimeters and diopters. Simple vertical adjustment to fit patient. Two way adjustable head and chin rests. Dual eye-level sighting system. Facilitates horizontal alignment. Positive fixation. Permits rapid measurement of central corneal area. Wide-angle eyepiece with engraved focusing scale. Brass and steel moving parts assure durability. Precision objectives. Achromatic lenses. Fits all standard instrument trays.