9 Things You Never Knew About Contacts
Contact Wearers, Unite
Sure, contacts are supposed to be the invisible way to improve your vision. But if you’re a contacts lens wearer, you know all the trepidation that comes along with the lenses. Losing or ripping one on a trip could result in a one-eyed vacation, and being without solution can become disastrous. Every contact wearer has inadvertently grossed someone out by sticking a finger directly onto an eyeball to poke a contact back into place. It’s not like we wanted this, anyway — 20/20 vision would have been nice. Here, some things you may not know about contact lenses.
1. Your contacts feel dry at the end of the night because they’re salty
Many contacts wearers complain of dryness at the end of the day, but it’s not because their contacts are really dry. It’s because they’re hypertonic, according to Joe Benjamin, OD, PhD, FAAO, president of the International Society for Contact Lens Specialties and professor in the school of optometry at the University of Alabama at Birmingham. Your eyes’ natural tears bathe your contacts in salt all day, and as water gradually evaporates from your eye, some of that salt is left behind on the lens. “[Salt] is good for the health of the eye, but too much saltiness is overdoing it,” Dr. Benjamin said.
2. Crying actually removes salt from your eyes
Yes, I said that tears are salty, but here’s something surprising: The tears you cry have less salt in them than the tears that remain in your eyes. Thus, when you cry, you’re again disrupting the salt balance in your eyeballs, only in the other direction. Now your contact isn’t salty enough, which may make it feel weird. Of course, crying irritates the eyes overall, and having a foreign body like a contact in them doesn’t help, Benjamin said. So maybe sport glasses for your next viewing of The Notebook.
3. There’s a new high-tech three-layer contact to help with these problems
After a decade of research on discomfort complaints of contacts wearers, contact maker Alcon released a new lens, the Alcon Dailies Total 1, earlier this spring. The new lens is the first ever to be made with three layers of material, instead of just one. Two layers of hydrophilic surface gel surround a middle layer of silicone hydrogel. Silicone hydrogel is much more water-soluble than a traditional one-layer lens. The layers bring increased moistness to the eyeball while still being thin and effective.
Benjamin has tried them in his patients, and he said they seem to like them as much as another specialty lens, Alcon’s AquaComfort Plus, which is treated with polyvinyl alcohol — the substance used to treat dry eye.
4. Daily contacts really are better for your health
Contacts come in several forms — including dailies, bi-weeklies, and monthlies. While Benjamin said many wearers opt for the longer-wear versions, he tries to encourage people to spring for dailies because they’re safest. Throwing them away at the end of the day means you never need a case to store them in, which means there’s no chance for bacteria to build up on a case and infect your eye. “No matter how well you clean a lens, you can never get all of the microbes off of it,” Benjamin said, noting that dailies cause fewer eye infections.
5. Dailies are only more expensive if you clean your contacts incorrectly
One of the main complaints Benjamin hears about dailies is that they’re more expensive than bi-weekly or monthly lenses. But if you factor in the amount of solution you’re actually supposed to use to clean your lenses, dailies come out to be the same price as longer-wear lenses. They’re also better for people who wear contacts infrequently, since lenses shouldn’t sit in solution for days
6. There are contacts you can wear at night to reshape your eyes
It sounds like the future — wear contact lenses at night and wake up with perfect vision in the morning. But this process of corneal reshaping, called orthokeratology, or ortho-K, has actually been around for years. An ortho-K lens reshapes the curvature of the cornea overnight, correcting for nearsightedness, and the cornea maintains the shape for the entire day. The process is recommended for kids and young adults with changing vision, and only works for moderate nearsightedness. It’s recommended for people who dislike wearing contacts and glasses, or who shouldn’t be wearing lenses (swimmers, for example, can trap bacteria in their eyes when swimming with contacts). The cost can vary, depending on how well a person responds to the treatment.
7. Hard contacts are the only type of lens that work for people with distortions
Hard contacts, the first type of contact lens, still exist, and it’s a good thing — they’re the only type of lens that corrects for distortions on the surface of the eye (like a scrap or scar). A hard lens doesn’t directly touch the eye, so inserting it traps tear fluid between the lens and the eye. This is enough fluid to correct any distortion or stigmatism of the eye. Soft lens are able to correct for stigmatisms, but not distortions. “For people with traumatic eye injuries, this is the only way they can see well,” Benjamin said.
8. Contacts were first made out of glass, in the late 1800s
In fact, contact lenses originally got their start as a correction device for people with seriously damaged eyes, rather than for people with regular bad vision, back in the late 19th century. Lenses were blown out of glass, and placed on the eye with a bit of animal jelly that would fill in whatever part of the eye was damaged to help people see again. It was only later that eye doctors realized this same technology could be used to correct for nearsightedness and farsightedness.
9. Contacts were originally inspired by telescopes
While the method described earlier was popularized in the late 1800s, and adopted for a broader population in the 20th century, the first prototype of a contact lens was developed in 1821. The developer, John William Herschel, was the son of the astronomer William Herschel, for whom the Herschel Telescope of Spain is named. Both men were familiar with grinding lenses for use in telescopes, and it was John who first conceived of grinding a similar lens at a much smaller scale to improve human vision.
reference from
everydayhealth.com