Why do people wear hard contact lenses?
- asks Lindsey from New York
Other than being generally awkward, I’ve spent most of my time since I was 13 getting things in my eye–or rather, getting things stuck onto my gas permeable, “hard” contact lenses. Other formative moments have had me blinking on command so friends and gathered revelers could see the tiny, glass-like chunk in my eye move and resettle.
About four weeks ago, when I was yet again ticking off the reasons why I was lucky enough to have thick lenses directly on my eyeball, it occurred to me that I had been reciting the same spiel–a strange eye shape, really really really bad eye sight–for more than a decade.
What if, the science had changed and I no longer needed hard lenses? What if I should have had years of soft contact wearing behind me, and I didn’t know it, because I was blithely tripping along following the advice of the eye doctor I had during my adolescence.
Turns out, he was a smart man (let the record show I never doubted him). For certain vision corrections, rigid gas permeable lenses provide clearer, more precise vision than soft lenses. This is mainly due to structural difference between soft and gas permeable lenses.
Since soft contacts are traditionally made with water, they can actually dry out, causing their shape to warp and preventing clear vision as well as becoming a potential irritant. To stay hydrated, soft lenses draw moisture from the eye, which can lead to dry eyes. Water also binds to tear proteins making contacts attractive to “pollutants,” such as lotions and soaps, which creates a chunky, gritty build-up on the contact.
Rigid lenses, being stiff, don’t change shape when the wearer blinks, so they stay precisely focused. Not only that, rigid lenses, unlike soft contacts, do not contain any water. Because they are made with silicone polymers, rigid lenses are more oxygen permeable, making them healthier for the eyes (though these days, some soft lenses, called “extended wear,” are made of silicone hydrogel–a substance that allows almost as much oxygen to flow through as rigid lenses, and is less water dependent ).
But this is not to say gas permeable lenses are problemless; they, too, have their downside. When you first get them, you can’t just pop them in right away. Rather, they are broken in by wearing them for increasing amounts of time as your eye adjusts to having a new lump of stuff in it (I believe my doctor told me my eyelid had to form a sort-of groove…). Even if you are lifetime wearer, leaving the lenses out for a few days means going through the process of again .
Also, rigid gas permeables must be scrubbed clean, and soaked, nightly–while soft contacts can be worn constantly, soaked or simply tossed. Hard contacts are more expensive too, as are cleaning solutions (up to eleven or twelve dollars a bottle). But if you don’t lose them or crack them, hard lenses last longer (that’s a big “if”).
So, it seems as though “hard” lenses–full of mystery, science, and silicone–still serve an important function for certain contact wearers. Some last interesting facts about contact lenses:
1. Rigid gas permeable lenses are not the “hard” lenses of yesteryear, which were actually made of an oxygen-impervious substance called polymethyl methacrylate–truly “chunks in the eye.”
2. Gas permeables can also be used for nifty technique called orthokeratology, in which the lenses are worn–usually overnight–to reshape the cornea, leaving the patient with 20/20 vision. The effects of this last only one or two days, however, which is probably why it hasn’t caught on with all contact wearers.
*An interesting side-note: if you are wanting the best of both worlds, there is a new contact out with a rigid center, and soft circumference. Check it out…