Eyesight

Ophthalmologists are medical doctors who specialize in treating the eyes. Optometrists have less training and specialized education, but now provide most primary eye care in the United States, routinely diagnosing and treating conditions that were outside their scope of practice half a century ago. FG Trade/Getty Images hide caption

Not seeing clearly can hamper a child's academic achievement, social development and long-term health, research shows. The right pair of glasses can make a big difference. FatCamera/Getty Images hide caption

In a study that tested the vision of people from a variety of professions, researchers at the University of California, Berkeley found that dressmakers who spend many hours doing fine, manual work seemed to have a superior ability to see in 3-D. Elena Fantini/Getty Images hide caption

The mantis shrimp has "hexnocular vision" (as opposed to our binocular vision), thanks to its three "pseudopupils" in each eye. KQED hide caption

Contact lenses are simple and convenient, but also medical devices. Erik Tham/Getty Images hide caption

A Nuremberg magnifier and wooden case, made in Germany around 1700. Before spectacles become easier to wear and more comfortable, hand-held models were more common than those for the face. Courtesy of the American Academy of Ophthalmology Museum of Vision hide caption

Logan Levenson had a cornea transplant to repair an eye after a fungal infection. Courtesy of Beth Levenson hide caption