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Solar Eclipse and Health

Solar Eclipse Image

Direct viewing of a full or partial solar eclipse can cause permanent eye damage. ARPANSA recommends viewing an eclipse using indirect methods.


Download Fact Sheet PDF (487 kb)

Eye safety and solar eclipses

A solar eclipse occurs when the moon passes between the sun and the earth, and the moon fully or partially obscures the sun. It is extremely dangerous to look directly at the sun even during a solar eclipse. You should never attempt to observe a total, partial or annular eclipse with the naked eye.

The safest technique for viewing a solar eclipse is indirect viewing. For example you can easily project an image of the sun onto a screen or you can view live streams on TV or online. Children's eyes in particular are extremely delicate and transmit more light through to the retina and are more susceptible to damage.

The use of eyewear marketed as 'eclipse glasses' has become more popular. Safe use of these glasses relies on the filtering ability of the lenses and the design of the frames. Even where the lenses are certified to meet the applicable standards, improper use of these glasses may still result in serious eye damage. Parents are recommended to be cautious when letting children use such glasses for observing an eclipse as children are even more at risk of serious eye damage because of the higher sensitivity of their eyes.

ARPANSA recommends that solar eclipse glasses should not be used to directly view a solar eclipse.

Things to remember

  • Viewing the eclipse can cause permanent visual loss.
  • Damage occurs rapidly without any pain.
  • Loss of vision does not occur until after the eclipse.
  • There is no treatment and children are especially at risk.
  • ARPANSA advises against any direct viewing of the eclipse.

Sunlight

The main hazards to the eye from very intense sunlight are from heat (infrared radiation), UVR (ultraviolet radiation) and from excessive visible light especially blue light. Even a momentary glance at the sun on a sunny day can focus a very intense amount of heat onto the back of the eye (retina). UVR can cause 'sunburn' to the outer surface of the eye (cornea). The least understood risk is from blue light which may also cause damage to the eye.

Is it safe to look at a solar eclipse?

Normally the sun is so intense that it is difficult and very dangerous to look at it directly. However, during a total solar eclipse so much of the sun is covered that a person may be tempted to stare at it directly.

It is possible to suffer serious and permanent eye damage by looking at any type of solar eclipse and there is no treatment. Children are especially at risk due to more light reaching the retina than adults. They may lack the ability to follow instructions correctly and have a greater temptation to look at a solar eclipse, not understanding the dangers.

Looking at the intense light from the sun even for just a few seconds can cause permanent damage to the retina. The retina has no sensitivity to pain and since the effects of retinal damage may not appear for hours there is no warning that an injury to your eye has occurred. The amount of time looking at the sun that will cause loss of sight varies from eye to eye but in all cases is only a matter of seconds.

Indirect viewing of a solar eclipse

The safest way of viewing a solar eclipse is to use indirect methods. An example is the projection method using two cardboard cards: cut a small pinhole in one of the cards and then use this card to project the image of the sun onto the second card.

For further information on eye safety and indirect viewing methods, refer to the following released on solar eclipses from the Australian Society of Ophthalmologists.

Solar eclipse eyewear

Solar eclipse glasses use filters specifically designed to reduce ultraviolet, visible and infrared light.

ARPANSA measured the UVR and visible light transmitted through a pair of readily available solar eclipse glasses to check if they met the transmission requirements of EN 1836 Personal eye-equipment – Sunglasses and sunglare filters for general use and filters for direct observation of the sun and AS/NZS 1338.1 Filters for eye protectors Part 1: Filters for Protection against radiation generated in welding and allied operations.

The results show that the particular solar eclipse eyewear tested meets the transmittance requirements of the above standards to provide protection for the direct observation of a solar eclipse.

Despite the lenses potentially meeting the standard, a major concern with most types of solar eclipse eyewear is the design of the frame which holds the lenses. In order to prevent stray light from reaching the eyes, the frame should be close-fitting, together with adequate light blocking material around the lenses.

An example is if these lenses were part of ski or welding goggles or full face shields. Most glasses are a generic adult design and easily fall off or out of position with movement, and may not fit certain face shapes and sizes, thereby exposing the eyes directly to the eclipse. Due to the potential issues around lens performance, design of the glasses, and inappropriate use, the use of solar eclipse glasses is not recommended.

Sample eclipse glasses

The Australian Society of Ophthalmologists states:

"There are risks associated with all forms of direct viewing whether using solar filters, unprotected viewing or viewing through optical instruments."

Optical instruments such as a telescope or binoculars focus the light.

References

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