Today there is a solar eclipse. Can I look at it with regular sunglasses if I only do so for a few seconds? What can happen if I look directly at the Sun?

Hello, Elena,

The answer is very clear: you should not look directly at the Sun during an eclipse using only regular sunglasses, even if they are very dark, polarised, or of good quality.

Nor do I recommend thinking that 'it will only be for a few seconds'.

Looking directly at the Sun can cause an injury known as solar retinopathy or photic retinopathy, which particularly affects the macula — the central area of the retina responsible for our sharpest vision.

The problem is that the retina has no pain receptors. This means you can be causing an eye injury without feeling any pain or immediately noticing that you are damaging your eyes.

Symptoms may appear afterwards, even hours later.

These may include:

blurred vision;

the appearance of a dark spot or blind spot in the centre of your vision;

distortion of images;

difficulty reading or making out fine details;

altered colour perception;

reduced visual acuity.

In some patients, vision improves gradually over the following months, but the damage can be permanent and may leave a lasting loss of central vision.

Why are regular sunglasses not suitable?

Because they are designed to reduce ambient brightness and protect us from ultraviolet radiation during everyday exposure, but they are not designed for looking directly at the Sun.

Even extremely dark sunglasses are insufficient.

To observe the partial phases of an eclipse directly, we need specially designed solar viewing glasses that comply with the international standard ISO 12312-2.

These glasses are thousands of times darker than conventional sunglasses.

Before using them, we should check that they are not scratched, punctured, worn, or damaged.

Can I wear two pairs of sunglasses on top of each other?

No.

Two, three or four pairs of sunglasses still do not become certified glasses for solar observation.

I also advise against using X-rays, smoked glass, photographic negatives, CDs, homemade filters or any other improvised method.

What about looking through a mobile phone?

We must be careful with that as well.

I do not recommend using the phone screen as an excuse to point directly at the Sun while we end up accidentally looking straight at it.

And we should never look directly at the Sun through binoculars, telescopes, cameras or other optical instruments without solar filters that have been specifically designed and correctly fitted to the front of the device.

This is even more dangerous because the lenses concentrate solar radiation and can cause serious eye injuries in a very short time.

Is there any moment during a total eclipse when it can be viewed without glasses?

There is one very specific exception.

During a truly total eclipse, only during the brief instants in which the Moon completely covers the bright surface of the Sun may you look directly at it.

But this is only valid if you are truly within the path of totality.

As soon as the smallest bright fragment of the Sun reappears, we must immediately put our eclipse glasses back on.

If you are not completely certain that you are in the totality phase, my recommendation is simple: keep your solar protection glasses on.

Special care with children

We must be even stricter when it comes to children.

They should not observe the eclipse without adult supervision, and we must personally check that the glasses are correctly in place before they look toward the Sun.

A child may remove their glasses out of curiosity at precisely the most dangerous moment.

What should I do if I have looked at the eclipse without protection?

If after looking directly at the Sun you notice blurred vision, a central blind spot, distorted images, colour changes or any loss of vision, you should seek an ophthalmological assessment as soon as possible.

Do not wait for pain to appear because, as I have explained, retinal damage can occur without pain.

My message for today is very simple:

Enjoy the eclipse. It is an extraordinary phenomenon, but our eyes are with us for life.

Only use glasses that are specifically designed and certified for solar observation. Conventional sunglasses are not suitable, regardless of their price, darkness or quality.

And for a few seconds of curiosity, it is not worth risking retinal damage that, in some cases, may stay with us forever.

Kind regards,

Doctor Florian A. Vallecillo Cabrera