Atlas of diagrams to accompany the Method of Cuignet

Historical Significance: This is a companion volume to a volume of text 'The method of Cuignet: or, retinoscopy. With an atlas of diagrams'. In 1873 the French ophthalmologist Ferdinand Cuignet (b.1823) used a simple ophthalmoscope to compare the variable reflexes in eyes which subjective testing had already determined to be experiencing different refractive errors. This was a qualitative test. By observing the size, brightness, speed or direction of the reflex Cuignet could now classify the patient's error in simple categories such as myopia, hyperopia or astigmatism. Somewhat misleadingly he called his technique keratoscopie, thinking that the cornea was responsible for his observations. Cuignet was a military surgeon. The civilian ophthalmologists, such as Edmond Landolt, looked down on him and did not give him the credit his (admittedly imperfect) discoveries deserved. In 1878 Cuignet's pupil M.Mengin published an accurate explanation, thereby proving Landolt's suggestion that the source of the reflex was the fundus rather than the cornea. Finally, in 1880, H. Parent (1849-1924) introduced the quantitative refraction test. It was now possible to measure the exact amount of refractive error using lenses. He also coined the term retinoscopy.