Herman Snellen

Herman Snellen was a Dutch ophthalmologist, born in 1834 and dead in 1908, who in 1862 introduced the Snellen chart for measuring visual acuity. He studied medicine at Utrecht under Franciscus Donders and took his degree at Leiden in 1858, then worked at the Netherlands Hospital for Eye Patients, whose directorship he took over from Donders in 1884 and held until 1903. He was also professor of ophthalmology at Utrecht from 1877 and researched astigmatism, glaucoma, the correction of vision with eyeglasses and eye surgery. His chart used optotypes, purpose-designed letters on a five by five grid, and became the global standard, still common in medical offices in the twenty-first century. He was elected an international member of the American Philosophical Society in 1894.