Herman Snellen might not be a name instantly recognizable to you, but if you’ve ever attended an eye test you’ll definitely be familiar with his work, even if you don’t realize it. Mr. Snellen is responsible for the creation of the famous eye chart that adorns every optometrist’s wall. He is remembered as an innovator in his field and has left a lasting legacy in the world of eye care.
Today marks the anniversary of Herman’s birthday. Born in 1834 in Utrecht, Netherlands, Herman followed in his father’s footsteps and trained as a physician. The year he gained his doctorate, he took up a post as an assistant physician in an ophthalmic clinic. This was the start of a 45-year long stint at the eye clinic, where he moved up the ranks to eventually become its leader until he left in 1903.
Snellen devised the eponymous chart that is now named after him in 1862 after previous charts had been created but none to the standard of Snellen’s. It uses optotypes – standardized symbols for testing visual acuity – of various sizes. It usually begins with one large letter at the top and is then preceded by lines of letters that decrease in size. The smallest letters that the patient can see unaided usually defines their level of visual acuity.
Snellen’s chart was the trailblazer and became a university known and accepted form for testing eyesight. Snellen was also an important contributor in the field of eye health, including areas such as glaucoma, astigmatism, and diseases of the retina and connective tissues.
Happy birthday, Herman Snellen!