An instrument for examining the cornea to see if it has an unusual curvature.
An instrument having a pattern usually of concentric black and white rings, which is reflected from the cornea in order to evaluate the corneal curvature.
An instrument for detecting abnormal curvature of the cornea. It consists of a black disk, about 20 cm in diameter, marked with concentric white rings. The examiner looks through a small lens in the center at the reflection of the rings in the patient’s cornea. A normal cornea will reflect regular concentric images of the rings; a cornea that is abnormally curved (for example in keratoconus) or scarred reflects distorted rings.