As a significant solar eclipse approaches, experts are emphasizing the critical importance of using certified eye protection and warning against the use of older or damaged eclipse glasses, which can cause permanent vision damage.
Looking directly at the sun without proper protection, even during an eclipse, can lead to severe retinal burns and irreversible vision loss, a condition known as solar retinopathy. The retina lacks pain receptors, meaning damage can occur silently and without the viewer realizing it.
Certified eclipse glasses must meet the ISO 12312-2 international safety standard. While some retailers may still have limited stock, availability is scarce this close to the event. For instance, Astronomy Ireland's certified glasses were available at a Dublin shop that closes at 5 p.m. In Cork, MTU Blackrock Castle Observatory is hosting an event with free, donated glasses, but availability is limited and distributed in a controlled manner to encourage sharing.
Using regular sunglasses, smoked glass, or homemade filters is insufficient to block harmful ultraviolet and infrared light. A common myth is that wearing multiple pairs of sunglasses offers protection, but this is untrue and dangerous.
Dangers of Uncertified and Degraded Viewers
Experts caution that eclipse glasses degrade over time. Older pairs, even those stored from previous eclipses, may have worn-out film that no longer provides adequate protection. Scratches or other damage can also compromise their safety. Kyla Black, Director of Optical Practice at Boots Opticians, advises checking glasses for damage by holding them up to a bright light; no light should be visible through the lenses if they are intact.
Dr. Greg Brown, an astronomer at the Royal Observatory Greenwich, recommends using glasses manufactured within the last decade. Even a brief, unprotected glimpse of the sun during an eclipse can cause harm.
Peter Smith, who suffered permanent retinal damage after using a welder's mask to view the solar eclipse 27 years ago, shared his experience. He still experiences visual disturbances, such as flashing dots, particularly when tired. Smith urges the public to use appropriate filters to prevent irreversible eye damage.
Mohamed Elalfy, a consultant ophthalmologist, highlighted that symptoms of solar retinopathy may not appear for several hours after viewing and can include blurred vision, a central blind spot, distorted vision, reduced color perception, and increased light sensitivity. While some vision may recover, permanent impairment is possible.
Safe Alternatives for Viewing
For those without certified glasses or who cannot find them in time, indirect projection methods offer a safe way to observe the eclipse.
One effective method is using a pinhole projector. This can be made with two pieces of card or paper. A small hole, made with a ballpoint pen, is punched in one card. Facing away from the sun, holding the card with the hole and a blank piece of paper allows an image of the sun to be projected onto the paper, gradually showing the eclipse's progression.
A common kitchen colander can also be used similarly. Holding the colander up to the sun and looking away from it projects multiple small images of the sun onto a surface behind it, creating a kaleidoscope effect of the eclipsed sun.
Another indirect method involves using a cardboard box, such as an empty cereal box, to create a pinhole viewer for a clearer image. This setup blocks ambient light, allowing a focused projection of the sun onto a screen at the bottom of the box.
Natural indirect viewing can also be achieved by standing beneath a leafy tree, where the gaps between leaves create numerous small images of the sun projected onto the ground, which will change shape as the eclipse progresses.
This year's eclipse is notable for its significant coverage, with some parts of Ireland expected to see up to 96 percent of the sun obscured. The eclipse is set to begin shortly after 6 p.m. BST, with the peak occurring about an hour later. The event will conclude shortly after 8 p.m. BST. While totality will not be visible in Ireland, it will be the most substantial solar eclipse in over 26 years, with the best viewing location in Ireland being Mizen Head in West Cork, where approximately 97 percent of the sun will be covered.