Early 20th century ophthalmoscopy tool. Ophthalmoscopic tools are used to examine the interior of the eye and measure its optical properties. This is a combined refractometer (to measure refraction) and ophthalmoscope (to examine the inside of the eye) dating from 1915, produced by the German Carl Zeiss company. It was designed by the Swedish ophthalmologist Allvar Gullstrand (1862-1930), who won the Nobel Prize for his work on the optics of the eye. The Carl Zeiss company is one of the world's leading optical equipment manufacturers.