For those who did not heed the warnings and looked at Monday's solar eclipse for an extended period without eye protection, here's how to tell if you have a problem.
A dark or dim spot in the center of your field of vision could indicate a condition called solar retinopathy, said Sunir J. Garg, a professor of ophthalmology at Wills Eye Hospital.
A person may also perceive the damage as "waviness," said Bisant Labib, assistant professor at Salus University's Pennsylvania College of Optometry.
This type of damage, the result of burning the retina, does not show up for an hour or more after exposure.
As of midday Tuesday, Wills Eye had no confirmed cases of solar retinopathy among a handful of patients who came in as a precaution. Penn Medicine, the University of Pennsylvania's health system, also had no confirmed cases.
There is not much a physician could do to treat a patient with solar retinopathy, other than to watch and wait. In many cases the damage is temporary, and recovery occurs after several months.
Eclipse-viewers who truly overdid it, however, could experience permanent spots in the center of their vision, Garg said. The phenomenon is similar to what occurs when a prankster shoots laser pointers at someone's eye, harming a part of the retina called the macula — the same region that is affected by macular degeneration.
"When they're horsing around their friends, they will shoot their own macula with these hand-held lasers," Garg said. "They will cook their macula, with 30 individual burns in their retinas."
With an eclipse, it is unclear just how long a person would have to look to cause damage. A second or two is unlikely to hurt, as the sun's rays are no more dangerous than in non-eclipse conditions.