After spending more than 2 months trapped underground, 33 Chilean miners are slowly being brought to the surface in a carefully orchestrated rescue mission - greeting the first light of day with protective sunglasses. How will the two- month ordeal affect their eyesight, and will there be any permanent damage?
“The 33 men have endured a unique situation, also from an eyecare perspective,” says Kesi Naidoo, optometrist and SA country manager of the International Centre for Eyecare Education. “It was a very unusual set of circumstances and I’m not aware of any first-hand studies of the potential effect of a sustained period of darkness on people’s eyesight.”
“However, I do expect the miners’ eyes to adjust within a day or two and that there will be no long-term complications,” he adds.
According to Naidoo, the miners are wearing sunglasses as a simple precaution and to protect them from initial discomfort when they are exposed to bright light for the first time in more than two months.
Rods and cones
“The eye’s retina contains two types of photoreceptors called rods and cones. The cones help your eye to adjust to bright light, such as daylight, whereas the rods are responsible for dark-adapted vision, such as night vision,” Naidoo explains.
He compares the light effect to going to the movies. “In the first few seconds, it’s very dark when you enter the movie theatre and you can’t see anything, but soon your eyes adjust. And, two hours later, when you leave the movie theatre, the light feels very bright and your eyes have to adjust again. Imagine what it would feel like if someone shone a bright light directly into your eyes - this is similar to what the miners would experience after being in darkness for an extended period,” Naidoo says.
Shock to the system
“The miners’ eyes have adapted to darkness, and they have been living in poor light conditions for more than two months. The sudden light exposure will cause severe discomfort – it will be a great shock to the system,” Naidoo continues.
“By wearing sunglasses and darkening the windows of the medical facility where they will be observed within the first day or two, the healthcare professionals ensure that the adaptation to light will take place a little more gradually.”
Naidoo expects the miners’ eyes to adapt back to normal within a day or two and does not expect any complications.
Asked whether the long-term exposure to humidity underground could have had an effect on the miners’ eyes, Naidoo replied “no”. “The eyes’ tear fluid protects the eyes, and unless someone had an existing eye infection when he got trapped in the mine, there should be no other eye problems present among the miners, apart from the discomfort of the initial first bright light.”
(Birgit Ottermann, Health24, October 2010)