A Portland man who experienced permanent eye damage from looking at the sun during a solar eclipse in 1963 is now warning others not to make the same mistake when they view Monday's total solar eclipse.
Louis Tomososki, who is now 70, said he was 16 when he watched a partial solar eclipse without any eye protection from his high-school baseball field in Portland, Oregon, according to Fox affiliate KPTV. He closed his left eye and viewed it with his right eye for about 20 seconds.
"That's all it took," Tomososki told KPTV. He now has a small blind spot in the center of his right eye, which hasn't gotten any better or worse since 1963.
Tomososki said he worries others could experience similar consequences if they don't take precautions during the solar eclipse on Monday, Aug. 21, which will be visible across the United States. [Has Anyone Ever Gone Blind from Staring at a Solar Eclipse?]
"Millions of people out there are going to be looking out at it … How many of them are going to say, 'Something happened to my eyes?'" Tomososki told NBC's Today Show.
Tomososki's condition is known as solar retinopathy, or damage to the eye's retina that happens from looking directly at the sun. This damage occurs because your eye's lens focuses the sun's rays on a single point at the back of the eye.
"If you take a lens that has that much power and point it directly at the sun, the energy becomes very high," and is enough to literally burn holes in the retina, or the light-sensitive cells at the back of the eye, Dr. Russell Van Gelder, a clinical spokesman for the American Academy of Ophthalmology (AAO) and director of the University of Washington Medicine Eye Institute in Seattle, told Live Science in July.
The damage occurs in the fovea, a spot in the retina that is responsible for sharp, central vision. As a result, patients with solar retinopathy may have blurry vision or a central blind point in their eyes, according to the AAO.
People with solar retinopathy show a very characteristic pattern of eye damage during an exam. "It looks like someone took a hole punch and just punched out the photoreceptive cells in the retina," Van Gelder said.
Indeed, Tomososki said his doctors can often tell that he once looked directly at the sun.
"Every time we go to an eye doctor now for an exam, they dilate your eyes and look in there, the first thing they say is, you looked at a solar eclipse sometime in your life," he said.
If you plan to look at the solar eclipse on Monday, you need to use special "eclipse glasses" or handheld solar viewers that contain solar filters so that you don't damage your eyes, according to the American Astronomical Society.
REMEMBER: Looking directly at the sun, even when it is partially covered by the moon, can cause serious eye damage or blindness. NEVER look at a partial solar eclipse without proper eye protection. Our sister site Space.com has a complete guide for how to view an eclipse safely.
Originally published on Live Science.