A solar eclipse will take place across Australia on Thursday morning. It will be most visible in the Ningaloo region of Western Australia. Thousands of people will flock to the small coastal town of Exmouth to witness this spectacular event, while Australians elsewhere will witness a partial eclipse.
It is imperative to take steps to protect your eyes from solar retinopathy – permanent eye damage caused by looking directly at the sun. Expert guidelines advise people never to look at the sun or a solar eclipse with the naked eye. Direct viewing should only be done with the proper use of approved solar eclipse glasses that meet an international safety standard known as ISO 12312-2.
Solar retinopathy, also known as solar blindness, has been recognized since ancient Greece. It struck astronomers, including Sir Isaac Newton, who once used a mirror to look at the sun and saw “afterimages” for months.
Looking too closely
In Turkey in 1976, 58 patients sought treatment for eye damage after a solar eclipse. While some experienced initial improvements, others suffered no change 15 years later.
In 1999, 45 people presented to the Eye Casualty of Leicester Royal Infirmary after a solar eclipse seen there. Retinopathy was confirmed in 40 of them. Seven months later, four people could still see “the ghosts of the damage” in their field of vision.
And after the solar eclipse of August 2017, 27 patients in the US state of Utah with vision concerns.
For people affected by solar retinopathy, the results can be devastating and lifelong.
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Read more: People have been predicting eclipses for thousands of years, but it’s harder than you might think
What happens to your eye when you stare at the sun?
Solar retinopathy is damage to the back of the eye (the fovea centralis in the retina) from exposure to intense light. It is usually caused by looking at the sun or watching an eclipse, but can also result from shieldless welding, looking at laser pointers, and from some surgical and photographic lighting.
A process called “phototoxicity” occurs when the energy in light forms harmful free radicals and reacts with oxygen in the retina. This disrupts the retinal pigment epithelium (a layer of supporting cells below the retina) as well as the choriocapillaris (blood vessels) below it.
Fragmentation of the photoreceptors, nerve cells in the retina that detect light and color, ensues and can lead to permanent loss of central vision.
Some wavelengths of light that cause solar retinopathy – such as ultraviolet-A radiation and near-infrared wavelengths – are not visible to humans, but cause solar retinopathy in just seconds. This exposure does not necessarily hurt at the time.
So watching eclipse — even with little or no visible light and viewed briefly without pain — can lead to vision loss.
There is no effective treatment
There is no proven treatment for solar retinopathy. Steroid drugs have been tried with no evidence of success, and you can make things worse in some patients. Antioxidant drugs are used in some eye diseases, but there are no studies showing a benefit in solar retinopathy. Vision may improve over time without treatment, but many patients are left with residual deficits.
The pillar of management is therefore prevention.
EPA/ALI HAIDER
Read more: A ‘hybrid’ solar eclipse is about to become visible in Australia. Here’s when and where to see it
How to recognize the correct eclipse specifications. 5 hints:
Only approved glasses absorb the correct wavelengths of visible, ultraviolet and infrared light. They have to:
- to be purchased reputable sellers to make sure they are not fakes
- display the correct safety certification (ISO 12312-2)
- not scratched, cracked or show any other signs of damage
- fit your face properly so that there are no gaps for light (check that they fit over your usual glasses if you need them for normal vision)
- be checked by looking at a lamp or light bulb – only light from the sun should be visible through true eclipse glasses. There is no risk of eye damage to this check, provided the previous steps are followed.
In Exmouth in WA has the Chamber of Commerce and Industry purchased about 20,000 eclipse glasses, which meet the international ISO safety standard.
Regular sunglasses, Polaroid filters, welding screens, X-ray film, neutral density filters, red glass filters, cell phones, and homemade sun filters are not safe to look at the sun or a solar eclipse.
AP Photo/Andrew Harnik
What if you think the damage is done?
Symptoms to look out for include blurred vision in one or both eyes within one to two days of exposure.
People may also experience blind spots, altered color vision, visual distortion (straight lines that appear kinked or wavy), micropsia (objects that appear smaller than normal), light sensitivity, and headaches. There may be no symptoms at all for the first hours to a day.
If you have symptoms, refrain from further darkening. Use dark sunglasses and painkillers (such as paracetamol) for photosensitivity and headaches. Make an emergency appointment with an ophthalmologist (or optometrist, general practitioner or emergency department, who may then refer you to a specialist).
Read more: Explainer: what is a solar eclipse?
However, what about the totality?
a total solar eclipse can potentially be viewed without eye protection, but only during the brief period when the moon completely obscures the sun (the period of totality).
This will only happen over the Ningaloo region of Western Australia, including Exmouth, just before 11:30am (AWST) and will take between 54 and 58 seconds, depending on the exact location. The Astronomical Society of Australia has an interactive map that eclipse watchers should visit to see the precise timing of totality in their location.
But this still has risks. Eclipse glasses should not be taken off until totality has set in, when the moon has completely covered the sun and it suddenly gets dark. Just before the sun rises again, the eclipse glasses must be replaced in order to continue observing the remaining partial eclipse.
Remember that totality will only occur over the Ningaloo region, so it’s not safe to see the eclipse anywhere else in Australia without protection.
A solar eclipse is a rare event. People will naturally be curious to observe it. By following the right advice, they can do it safely.
