The True Inventors of the Keratoscope and Photo-Keratoscope

Abstract

Synopsis As early as 1670 Isaac Barrow and Isaac Newton, at Cambridge, were aware of the production of astigmatism by oblique pencils of rays on a spherical lens. Thomas Young (1800) and G. B. Airy (1825) independently discovered ocular astigmatism. By viewing the image of objects reflected on the anterior surface of the cornea, the cornea may be examined for any defects of its surface (including astigmatism). The corneal “reflex” had been examined as early as 1619 by Christoph Scheiner, and as a “clinical” test, by using a candle flame, by David Brewster (1808). An instrument (the keratoscope) for examining the anterior surface of the cornea for the detection of abnormality was first invented by Henry Goode (1847) of Cambridge University. Antonio Plácido, formerly credited with the invention, independently invented a keratoscope in 1880. Correspondence of Plácido and Emile Javal (Paris) reveals that Placido invented the photo-keratoscope, formerly attributed to Allvar Gullstrand (1896) in Sweden. Javal is credited with the first description of the application of a photo-keratoscope (independently invented by him) in a specific case of ocular abnormality.