Seeing a solar eclipse with the naked eye can make you blind?

Are you tempted to stare at a solar eclipse with the naked eye? Even though the sun is quite far from the earth, about 150 million kilometers, it turns out that looking directly at the sun can still cause serious and sometimes irreversible eye damage.

Why can't we look directly at the sun?

There's a reason why we can't (and shouldn't) look directly at the sun. Simply put, staring at the sun in normal circumstances is indeed very difficult because its rays are too bright and dazzling. But the response to squinting at the glare or rushing for shade — be it with a hand or a pair of sunglasses — is an instinctive human reaction to avoiding direct exposure to sunlight as much as possible for the sake of one's own safety.

Glare is a form of human self-defense from sunlight

The sun is fundamentally the source of the constant hot bursts of heat. Once you decide to look at the sun with the naked eye, the sunburn will start to "roast" the eyeballs. UV rays are the type of sunlight that can damage the eyes the most, especially when reflected off sand, snow or water. The cornea (the outer layer of the eye that is transparent) will blister and crack as a result of excess UV exposure.

This process is very similar to how the sun can burn your skin, which you may experience when it's hot outside. Symptoms of this condition, known as photokeratitis, usually appear several hours after the damage occurs and cause excessive tear production. In addition, the eyes are red and inflamed, as well as a cramped sensation like you have rubbed your eyes with sandpaper.

So when you look directly at the sun for just a moment, the heat produced is so concentrated in the retina that it is enough to burn and scorch it. To make matters worse, because the retina doesn't have pain receptors, you don't know the damage has occurred until it's too late.

Sunlight can damage the eyes

If you dare and hold on to staring at the sun any longer, then you will suffer retina and macular damage. The retina is the tissue at the back of the eye to project images to the brain, which is very sensitive to light.

In its normal state, the pupil of the eye will shrink when exposed to bright light, but the amount of light entering the eye is concentrated in the macular tissue. Excessive UV exposure from staring at the sun for too long then burns the retina, which can cause temporary partial blindness to permanent blindness which forms a dark circle right in the middle of your field of vision.

Do not look directly at a solar eclipse with the naked eye

Looking at the sun during a solar eclipse is not much different from gazing at the sun on a normal day. The difference is that our natural reflex will usually automatically turn away from the glare of the sun if we stare too long. This is naturally regulated by the brain.

Now, the calm atmosphere during a solar eclipse lowers self-awareness so that we "forget" to squint and take a long look at the sky. The pupils also widen automatically when looking at the cloudy sky. This can unwittingly increase the amount of UV radiation landing on the retina and make you more susceptible to eye damage.

A solar eclipse is never safe to see with the naked eye, regardless of its type (partial, crescent, ring, total, or phase of "journey" from partial to total). Even when nearly 99% of the sun's surface is darkened by the moon, the tiny ring of sunlight peeking out from behind the moon still emits enough UV light to burn your eyes, says Ralph Chou, an emeritus professor of optometry at the University of Waterloo in Ontario, on Space.. The effect will be the same as when you stare at the sun directly.

But can humans really go blind after seeing a solar eclipse? It may not be right away, but the damage you may experience can be so severe that your eyes will no longer be able to see very well in detail. To date, there have been more than 100 cases of serious and permanent eye damage caused by people staring at the solar eclipse for too long, said Ralph Chou. However, there is an easy way to avoid this damage: Wear protective glasses when viewing a solar eclipse.

Wearing sunglasses during an eclipse is not enough to protect the eyes

An ordinary pair of sunglasses will not adequately protect the eyes from UV rays during a solar eclipse. To be able to view (and photograph) a solar eclipse, you will need glasses or a camera filter specially designed for a solar eclipse. This special lens can reduce the intensity of light entering the eye to a safe level.

It is important to make sure you use this device properly. Put your lenses / glasses right in front of your eyes, then look up to see the sun. Never leave while still looking at the sun until the moon has completely covered the sun, or when you turn away from the eclipse.