I. On a distinct form of transient hemiopsia

Abstract

From a comparison of the different accounts of “Hemiopsia,” “Halfvision,” or “Half-blindness,” given by Dr. Wollaston (Phil. Trans. 1824, p. 222), M. Arago (Annales de Chimie et de Physique, tom. xxvii. p. 102), Sir David Brewster (Phil. Mag. 1865, vol. i. p. 503, and Transactions of Royal Society of Edinburgh, vol. xxiv. part 1), the Astronomer Royal (Phil. Mag. July 1865, vol. ii. p. 19), Professor Dufour (in a letter to the Astronomer Royal), Sir John Hersehel (Familiar Lectures on Scientific Subjects, p. 406, Lecture IX., and private letters), Sir CharlesWlieatstone (in a private letter), Mr. Tyrrell (On the Diseases of the Eye, 1840, vol. ii. p. 231), and the author of this paper, it is plain that there are different forms of transient Hemiopsia, irrespective of the wide primary distinction between the transient and permanent forms, which have all been included under the same name Hemiopia or Hemiopsia. It seems that Wollaston, Arago, Brewster, and Tyrrell are describing one form of the transient affection, while Sir John Herschel, Sir Charles Wheatstone, the Astronomer Royal, Professor Dufour, and the author agree in describing another.