In the late 1800s, when doctors first began looking into eyes with ophthalmoscopes, they believed that the drusen they observed represented some type of infection, or at least inflammation, of the choroid. (scientificamerican.com)
An indirect ophthalmoscope sits on the vet's head, providing optics and a light source, while a focusing lens is held in the examiner's hand to visualize the retina. (cavaliercanada.com)
Babbage is also credited with inventing the cowcatcher, dynamometer, standard railroad gauge and heliograph ophthalmoscope as well as uniform postal rates, occulting lights for lighthouses and Greenwich time signals. (scientificamerican.com)