Your contact lenses are a barrier between your cornea and the rest of the world. While this may not seem like a bad thing, it is. Your cornea, like every other part of the body, requires Oxygen. Too little oxygen, and complications begin to arise. So what happens when you fall asleep with your contact lenses in? Your cornea is being denied oxygen by the lens itself. This leads to a condition known as hypoxia.

Corneal hypoxia changes the rate of metabolism in the epithelium. This in turn causes a decrease in glycogen, and makes the cornea more sensitive and prone to adhesion and refractive error changes. Continued progression includes corneal ulcers.

Since the cornea is more adhesive, this increases the chances of any buildup on the cornea itself, including protein buildups, which cause bacterial infections and corneal ulcers. Short term effects include extreme intolerance to contact lenses. Lens intolerance can be overcome by RGP Contact Lenses, but by this point, you should just ditch them all together. Give your eyes a chance to heal, and suck it up and wear glasses.

One of the more short-term effects of leaving your lenses in for weeks/months/years at a time is a contact lens infection*. I had a number of these over the course of a few years before my optometrist switched me to another brand of lens. Acquiring one of these infections is not a fun experience, and it can ruin your eyesight.

Causes:
  • Wearing lenses for long periods of time - especially lenses that aren't specifically designed for this purpose.
  • Placing "dirty" lenses into one's eyes.
  • Improper storage or cleansing of the lenses.
Common Symptoms:
  • A lens that "won't remain centered in your eye." If it seems like when you blink that your lens is being pulled either too far upward or downward in your eye, it's likely an infection. This is both the first symptom to appear and the most common.
  • Thick, colored mucus buildup either on the lens itself or throughout the eye. If you're careless, the mucus will start to deposit on your eyelashes. Needless to say, this is not often listed as a beauty tip.
  • Persistent tearing of the eye.
  • Small, raised bumps on the inner wall of the eyelid.
  • Intense pain or bleeding in the eye.
Treatment:
  • Most of the time, the infection will remedy itself after roughly a week of not wearing lenses. However, seek treatment. Your vision is, you know, important and such.
  • If you suspect you have a contact lens infection, immediately remove the lens from your eye and schedule an appointment with a specialist.
* - Although this seems to imply that it's the actual lens that's infected, it's rather an infection caused by the lens. However, the slightly confusing name is also the most commonly used, and thus is what is used here.

I stared up at the street lamp moon and wondered
how it could justifying hiding the night from me. The stars
were headlights on the wet grass. Lately,
I have been tripping on the holes in my day much more frequently.
They started out small, the holes. They were momentary lapses
into sanity, a defined detour. They were a piece of night
in a day of street lamps and traffic lights. Today is different.
The holes are larger and they disrupt my vision
with the persistence of a soldier. I have never met a soldier,
but if I did, I would wish him the best and warn him
of these holes. They can be a bit distracting
when one is trying to protect his fellow man. I used to be a visionary,
but now I wear contacts. Insanity will save us all
one day, once we stop worrying about the eyes of the world.

As the lamplight lit the cigarette smoke sky, I began to remember
my home, the place I knew before the holes. My mother
always argued greedily that, “Home is where the heart is.
When you are home, there is your heart.”
While I would never argue with my mother, she is wrong.
Home is not where the heart is, it is where the heart
decides it should be. Homes are the holes in the day
where your heart makes great leaps of faith
and lands in the soft grass.

There is only one conclusion I can draw from the persistence
of these holes as they threaten my insanity. Take great pains
in choosing the hole you fall into. Once you let go,
there is no looking back.

An interesting anecdote for hard contact lens wearers:

I was told years ago that my vision is too bad for soft lenses, and have been wearing hard contacts since I was in high school. Hard lenses are not available in extended-wear varieties (a concept I'm not comfortable with to begin with, even in soft lenses), so I never left my contact lenses in my eyes for extended periods of time on purpose, and only rarely wound up, by accident, falling asleep with them in (everybody does this from time to time). I would, however, wear them for 16+ hours every day because I can't see without them and I hate, hate, hate, wearing glasses.

Every optometrist warned me to take my lenses out every night. It's not good to leave contact lenses in your eyes for days at a time if they're not designed for it.

What nobody told me was that I should be getting them replaced every year.

When I was wearing glasses, I had gotten used to my vision getting worse on a yearly basis. I would need a new prescription every time I went to see the eye doctor. When I got my first pair of contact lenses, things seemed to level out and my vision stabilized. So I didn't go see the optometrist as often anymore, usually only if I lost or broke a lens and needed a new pair.

This means that for the last four years I had been wearing the same pair of hard contact lenses. Apparently, this was not good for my eyes.

According to my new optometrist, over long periods of time, the chemicals and other biological nastiness of your eyeball will warp and deform hard contact lenses. Continuing to place them in your eyes will then warp and deform your corneas. The process was so slow that I didn't even notice until it was well under way, when I started feeling like something was in my eye from time to time but couldn't find it or couldn't wash it out. Fortunately for me, it turns out this is only temporary, and although it can take up to a year for the eye to pop back into shape, it will eventually do so.

As a side note, a friend of mine got some new contact lenses recently that were supposed to do this on purpose. The theory is that, for a person with a weak prescription, sleeping with hard contact lenses specially shaped to deform your eye in the right way, carefully measured and monitored by the optometrist, will improve your vision. It takes several days for the reshaping to take place, and if you stop, over the course of a couple of weeks your eye will return to its normal shape. The process was too uncomfortable for him, though (not everyone is good with hard contact lenses, and I would imagine even fewer would be good with intentionally malformed ones), and eventually decided to just wear his glasses.

The good news was that contact lens technology had advanced since I was in high school and they now make soft lenses in my prescription. The bad news was that over the course of last year, I had to get several different pairs of contact lenses (thank goodness for my vision plan through work) because my eyes were reshaping themselves and a pair would only fit correctly for a while. The first pair lasted a couple of weeks, the second a month, the third a couple of months, and the fourth about six months. This brings me to January, 2008, and I have a doctor's appointment tomorrow to get what I believe will be my final pair of contact lenses.

Wait a minute, your final pair? Haven't you learned anything from all this? You need to go back next year and get a fresh, new pair.

Not necessarily, because I'm sick and tired of all of this already. The doctor said I'll need to wait one year after my eyes have reshaped, and once we're certain everything is back to their normal conditions, I'm going to get laser eye surgery and correct my vision once and for all.

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