Q&A: A Henry Ford Health ophthalmologist on how to watch solar eclipse without damaging your eyes

On Monday afternoon shortly after 3 p.m., millions of eyes will turn to the sky to watch the sun become fully eclipsed by the moon — a once-in-a-lifetime event visible across 15 states, including Michigan.

But to watch this otherworldly marvel without proper protection could result in permanent eye damage, Senior Henry Ford Ophthalmologist Dr. Nitin Kumar said.

Even a brief glance at the sun can lead to solar retinopathy, or damage to the retina, which can cause permanent vision defects.

Kumar practices medicine in Sterling Heights, where the sun will be about 95% eclipsed, and he plans to view the phenomena safely through solar eclipse glasses.

Below is a conversation with Kumar about how to enjoy the eclipse safely. Some answers have been edited for length.

Question: Can you look directly at the eclipse, you know, with no protection?

Answer: If you are actually in totality, yes. But you don't want to do it because you may not time it exactly right. If you don't time it exactly right, you're going to end up damaging your retina. Ideally, you will be wearing some sort of proper filter protection for your eyes, so that you can watch it as it goes from 99% of totality to a complete eclipse — that transition is what is supposed to be the most amazing part. Even if I knew I was going to be in a place where there was totality. I would still use proper protection for my eyes.

Q. Why shouldn't people look directly at the sun when it's partially eclipsed?

A: The front of the eye is designed to focus light on the retina and that's what's happening whenever you look at anything, that's why you see things clearly. If you look at the sun, it's focusing rays that are damaging directly onto the retina. Think about if you have a magnifying glass and you are on the sidewalk, you're focusing the light on a bug or piece of paper and you can make a little burn. That's exactly what you're doing to your retina when you are looking directly at the sun.

The retina has a layer of cells called the photoreceptors, and those photoreceptors are actually what take light and turn it into electricity. Those cells get damaged when you are looking at the sun. For the most part, damage that occurs is often permanent.

Q. What is the most common misconception you've heard from people about looking at an eclipse?

A: People will have proper protection from the sun for other things like a really good pair of sunglasses, or welder's glasses, or some sort of eye protection that makes it dark. But then they feel like that would be enough to look at the sun. That's not good. Even if you have UV protection in your sunglasses, that is not good enough to look at the sun. The International Organization of Standards has a specific standard, ISO 12312-2, and that's the standard for making any sort of filter to look at the sun. You want to make sure that any sort of protection that you have is meeting that qualification.

Regular sunglasses do not meet that qualification. I don't care how good they are, or how expensive they were.

Q. What are the symptoms of permanent eye damage caused by looking at the sun?

A: Think about when you look at a bright light and you sort of have an afterimage there — that will remain there. That's what solar retinopathy looks like. If you look at the sun, you'll have that afterimage there. If it doesn't go away then you looked at the sun for too long and you've damaged those photoreceptors. They can maybe heal to some extent, but a lot of times they don't and we don't have any treatment for this. You only get one set of photoreceptors for each eye.

Q. What protection do you need to view an eclipse and how can you tell that it's sufficient to protect your eyes?

A: There are ways to directly look at the sun and indirectly look at the sun. Indirect ways are these pinhole devices that you can make. What you're doing is you're having a picture of the sun go through this little pinhole, the light rays are going through a pinhole and you can see the eclipse coming and covering the sun. That is not going to hurt your eyes at all because you're not actually looking at the sun, you're looking at the shadow.

To look at the sun directly you have to have glasses that conform to that standard, the ISO 12312-2. Any eye protection that you get should say that ISO number on it, and that's the way you guarantee that you are wearing the proper eye protection.

Q. How do you view an eclipse safely through a camera or a telescope lens?

A: You can find shielding for your telescope that can go onto the end and you can look at the sun. There are astronomers that do that all the time, however, it needs to have the proper shield. Eclipse glasses are super dark. It's not like you're just wearing a dark pair of sunglasses. You want to filter out a good amount of that light that's coming from the sun. The same thing applies whether you're looking at it through your own natural lenses or your glasses, lenses, or a telescope, binocular or camera lens.

Q. Is there anything else important that you think eclipse viewers should know?

Answer: I think the most important thing to know is that it is really, really bad to look at the sun without proper protection. It can cause permanent damage to the vision. Don't do it. That doesn't mean you can't enjoy the eclipse. There are direct ways to look at the sun. There are indirect ways to look at the sun. There are very easy ways to form these indirect ways to look at it even if you haven't ordered your eclipse glasses by now and you can't find a pair.