If your mother told you never to look directly at the sun, she was right. Solar retinopathy is damage to the light-sensitive retina at the back of your eyes, and occurs most often from looking directly at the sun.
This post looks at why this might occur and what you can do to protect your eyes.
Why look at the sun?
Common reasons include observing solar eclipses, religious rituals (especially at historic sites around the summer or winter solstice) and even sunbathing. But the sun is not the only source of damage. Other sources of high-energy light exposure can also cause this condition. Arc welders can also suffer from this condition, as can patients undergoing eye surgery, where a strong light is used to illuminate the back of the eye. (Normal examination of the back of the eye during an eye exam does not pose any risk).
Can I go blind from looking at the sun?
The damage that occurs in solar retinopathy is not thought to be thermal – i.e. a direct burn – but rather a photo-oxidative effect of exposure to strong light. This means the high energy UVA light that is not absorbed by the cornea and lens can penetrate through to the retina. Here it causes the release of free radicals in the delicate structures at the back of the eye, causing retinal damage.
Is the damage permanent?
Solar retinopathy is experienced as a sudden deterioration in vision, and may last several weeks or months but most often resolves without treatment. While your visual acuity (i.e. your ability to read the eye test letter chart) may return to normal, blind spots may remain, indicating permanent damage to the light receptors. Light receptor cells (rods and cones) cannot reproduce themselves. You get one set for life. If some die, they are not replaced. If you don’t want to risk permanent damage, the advice is simple – don’t ever look directly at the sun.
How long is too long?
Studies show that damage can occur very quickly – with even 1 minute of exposure capable of causing symptoms. Most common symptoms are blurred vision, a blind spot in the middle of your vision, distortion in the colour or shape of things, light sensitivity and headache. You can have all of these symptoms or just one. Usually both eyes are affected, but this condition can also occur in one eye only. Vision can be mildly to severely affected, depending on the duration of exposure, intensity of light, as well as your age (older people have naturally more protection from their crystalline lens).
How is it treated?
If you suffer from these symptoms and have recently been exposed to direct sun or other high energy light, see your optometrist. They will examine the back of your eyes and often take an OCT of your retina to look for underlying signs of damage. These images can be used to track your progress over time as the damage resolves. There is no specific treatment available to reverse the damage.
How can you safely view a solar event?
- Don’t look at the sun! Not even for a few seconds, such as to observe a solar flare or eclipse.
- According to NASA, it is NOT safe to observe the sun through sunglasses of any sort, smoked glass or coloured film.
- If you do wish to observe the sun, use a filter or projector. A pair of binoculars or a telescope can be used to project the sun onto a screen. You can also make a pinhole projector from 2 pieces of paper.
- Welders’ glasses rated 14 or higher can be used to observe the sun.
- Eclipse glasses are also available that are approved for observing solar events.