Looking at a solar eclipse without proper eye protection can cause "eclipse blindness" or retinal burns, also known as solar retinopathy, which can cause temporary or permanent damage to the retina (the back of the eye) that transmits what you see to the brain. This damage can occur without any pain and can take a few hours to a few days after viewing the solar eclipse to realize the damage that has occurred. The damage can even lead to permanent blind spots or distortions in your vision. The remaining crescent Sun during the partial phases of a solar eclipse is still intense enough to cause a retinal burn, even though illumination levels are comparable to twilight.
To prevent damage from a solar eclipse, it is important to use proper eye protection. Never look directly at the sun during a solar eclipse (except during the very brief time the sun is in total eclipse; and even then, with proper eye protection) . Proper eye protection includes certified solar eclipse glasses that cost about $1 and are typically made of paper and have a dark film covering the eyes. Do not use sunglasses, smoked glass, photographic negatives, or any other filters that are not specifically designed for viewing a solar eclipse.
If you notice a spot or loss of central vision that lasts longer than a few minutes after viewing a solar eclipse, you should visit your optometrist to check for any damage. Children are especially at risk for improperly looking at an eclipse.
