Experts are warning against directly looking at the upcoming total solar eclipse in Western Australia — even with eclipse glasses — due to the risk of permanent eye damage or even blindness.

Up to 50,000 visitors are expected to descend on the state's north-west to witness a total solar eclipse in Exmouth and partial eclipse in surrounding areas on April 20.

Both the Department of Health and the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) have warned eclipse-chasers could sustain potentially irreversible eye damage if they looked directly at a total or partial eclipse.

They said it was only safe to view an eclipse indirectly, such as through a pinhole viewer or by watching a livestream. 

ARPANSA also said eclipse glasses should not be used to directly look at a solar eclipse.

Assistant Director of Ultraviolet Radiation Measurements Stuart Henderson said while there were Australian and international standards for solar filters, there were still risks.

"If they happen to be damaged, such as being scratched or have a small puncture or something in them, then you're not going to be getting the protection that they could provide," Dr Henderson said.

"The problem is, there's a lot of moving parts in that a lot of things have got to go right and if anything goes wrong, well, then the damage can be can occur very quickly.

Permanent damage

Exmouth is one of the very few accessible places in the world where the total solar eclipse will be visible.

While the total solar eclipse will last for only 62 seconds, ophthalmologist Steve Colley said it was important the warning was taken seriously as permanent damage could be done very quickly.

"The visible light [is] cut out by the solar eclipse, but the ultraviolet light and infrared light still get through, and it's the ultraviolet light that can do a lot of damage," Dr Colley said.

He said people may also not be able to feel the damage it is causing to their eyes.

"It's likely to be painless initially, although if you do damage your retina, the cells around it do have some pain fibres, so you feel some discomfort down the track, it may even be hours down the track."

In the UK following the August 1999 solar eclipse, 45 people presented to the Eye Casualty of Leicester Royal Infirmary.

Seven months later, four of them still had symptoms of focal burns to the retina.

Another study observed 58 patients in Türkiye who presented with eye damage after the April 1976 eclipse.

It found while some vision improvements occurred in the first month, whatever damage remained after 18 months, was unchanged 15 years later.

Viewing of total eclipse

The Exmouth Chamber of Commerce and Industry has purchased just over 20,000 eclipse viewing glasses, which have been put up for sale throughout the region.

The ECCI chief executive Sarah Booth said the glasses were compliant with all Australian and international standards, and fully certified.

"We feel that not providing access to such glasses increases the risk of people taking glances and causing permanent eye damage," she said.

The Department of Health said people choosing to use eclipse glasses should ensure they met Australian standards and were purchased from a reputable retailer.

It also advised against using dark glasses or welding shields for looking at the eclipse.

Consumer Protection said it had not received any reports of fake or sub-standard glasses being sold.