Donders, Frans Cornelis

(born May 27, 1818, Tilburg, Neth.—died March 24, 1889, Utrecht) Dutch ophthalmologist. His study of “muscae volitantes” (spots before the eyes) resulted in Donders' law, stating that the rotation of the eye around the line of sight is involuntary. His research improved diagnosis, operative treatment, and use of eyeglasses for vision problems. He found that in farsightedness the eyeball is shortened, resulting in light rays being focused behind the retina (1858). His finding that astigmatism is caused by uneven corneal and lens surfaces (1862) created the field of scientific clinical refraction. His On the Anomalies of Accommodation and Refraction (1864) was the first authoritative work in the field.