DISADVANTAGES OF HARD CONTACT LENSES
DISCOMFORT
Hard-lens wearers point out with a sense of irony that “they don’t call them ‘hard’ for nothing,” and suspect that the real reason their lenses are called hard has as much to do with the difficulty in getting used to them as with their physical rigidity. Initially a hard lens causes everyone some discomfort. (The amount varies, but at no time should you feel real pain. If you do feel sharp pain, either the contact lens has been improperly fitted or there’s something under it.)
Hard lenses feel uncomfortable at first because, although the edges are thin and perfectly smooth, they’re basically inflexible. Every time you blink, the edges of your eyelids bump against the edges of your lenses, making you very aware that the lenses are there. Ultra-thin lenses, with a central thickness of .035 mm, will flex unnoticeably a bit when you blink, and this is mostly beneficial to the tear-pumping action. You’ll still feel as though there’s something in your eyes (there is!), but the flexibility will allow more tears to flow beneath the lens, thus lubricating the cornea in a very effective manner.
Another source of discomfort with conventional hard lenses is that, as mentioned earlier, they’re made of a plastic that allows neither gases nor moisture to pass through. For the “pumping action” to work, resulting in the vital tear exchange process, the lenses must be fitted very carefully: loose enough to allow the lenses to move slightly, but not so loose that they slip around too much and impair vision.
A by-product of the fact that hard lenses don’t hug the cornea is that tiny particles of dust and dirt in a polluted atmosphere can lodge beneath the lens, causing discomfort, tearing, and redness. Your tear production may be stepped up sufficiently to banish the offending specks, but more often than not you’ll have to remove the lens and clean it.
OVERWEAR AND UNDERWEAR
No matter how well your contacts fit, there’s some oxygen deprivation occurring. Eventually your cornea needs a little “R and R”: rest and recuperation. This varies from patient to patient, but the average time that hard lenses can be worn without removing them is about eight hours. If you overwear your lenses by exceeding your wearing schedule, your eyes will rebel and reward you with pain, redness, and blurred vision. With soft lenses signs of overwear take longer to develop. On the other hand, underwearing hard lenses by cutting down on the hours or frequency of wear tends to reverse the adaptation process; lenses should be worn the same number of hours every day. Maintenance of a constant daily wearing schedule is essential for the hard contact lens wearer. Intermittent wearing is definitely unacceptable.
MOLDING AND SPECTACLE BLUR
Have you ever noticed how a ring leaves a slight indentation on your finger? A hard lens temporarily molds the cornea in the same way. The amount of corneal molding depends upon the fit of the contact lens and how long it’s been worn. Molding isn’t harmful, but you will experience blurry vision after you’ve removed your contacts and put on your glasses. This is called “spectacle blur.” Gradually your cornea will assume its normal shape, a process that can take anywhere from a few minutes to several hours. At that point vision with spectacles will be clear.
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