Cover image courtesy of Mr Richard Keeler, Curator, museum of the Royal College of Ophthalmologists.

Question: What did Ramsden, Wollaston, Gauss, Purkyne (Purkinje), Javal, Schiotz, Landolt and von Helmholtz have in common?

Answer: The keratometer.

An ophthalmometer measures the optical constants of the eye and is derived from the Greek words, ophthalmos—the eye and metros—the measure. A keratometer only measures the curvatures of the anterior surface of the cornea. It provides information on the spherical and astigmatic components of the corneal curvature and also the axis …