They should have sent a poet

January 25, 2011 10:55 AM

One contact decaying faster than the other. Why?

I have astigmatism in both eyes; left is 160 versus right at 10.
Of course you're not an eye doctor, but mine couldn't explain this situation. It seems that my left contact will deteriorate in condition and slide around much more than my right, meaning I have to replace the left 2-3x more often than the right.

Can the astigmatism figures explain this? Any experience in this matter appreciated.

posted by MangyCarface to Health & Fitness (10 answers total)

Do you have a habit (perhaps unconscious) of rubbing your left eye?
posted by charmcityblues at 11:07 AM on January 25, 2011

I have slight astigmatism in both eyes, but they are both about the same. I found that one brand of contacts has worked better than another, and there have been times when I have worn one brand in my left eye and a different brand in my right because I couldn't afford the more expensive brand for both eyes.

Have you tried a different brand of contacts? How often are you supposed to replace them? How often are you actually replacing each contact?
posted by rhapsodie at 11:17 AM on January 25, 2011

Best answer: Wouldn't your left contact be subject to more mechanical stress just because it's toric? Those lenses need to stay in the same orientation in your eye in order to correct astigmatism, and are typically thicker at the bottom, so that blinking displaces them to the right position just because of the weight. Wiki on toric lenses:

If one eye has astigmatism and the other does not, the patient may be told to use a spherical lens in one eye and a toric lens in the other. Toric lenses are made from the same materials as regular contact lenses but have a few extra characteristics:

* They correct for both spherical and cylindrical aberration.
* They may have a specific 'top' and 'bottom', as they are not symmetrical around their centre and must not be rotated. Lenses must be designed to maintain their orientation regardless of eye movement. Often lenses are thicker at the bottom and this thicker zone is pushed down by the upper eyelid during blinking to allow the lens to rotate into the correct position (with this thicker zone at the 6 o'clock position on the eye). Toric lenses are usually marked with tiny striations to assist their fitting.

Your right eyes is ten degrees off, and your left eye is 160 degrees off, so there just may be more compensatory rotation happening when you're blinking, and more wear and tear from that alone. Is your left eye also more strongly astigmatic when you look at the diopters value in your prescription? The left contact may be much more thick at one end than the other contact, and this could also stress it.
posted by maudlin at 11:25 AM on January 25, 2011

I have astigmatism in both eyes, but my left contact lens has always needed to be replaced much more often than the right, to the point where I always order at least an extra box of the left each time. I've always assumed that it's got something to do with how I take them out and put them in - the difference in angles or hands or something.
posted by something something at 12:05 PM on January 25, 2011

Data point: up until this week, I wore a toric lens in my right eye and a regular spherical lens in my left (I now have dumped the toric because the extra cost and fuss wasn't worth it for pretty mild astigmatism), but it was my right lens that wore out somewhat faster. I typically was running about a 5 lens disparity on two boxes of 30.
posted by maudlin at 12:15 PM on January 25, 2011

this is interesting bc i too have one contact lens (my right one) that i have to replace more often than the other, so i am curious if anyone has an answer as to why.
posted by violetk at 1:12 PM on January 25, 2011

Back when I wore non-disposable contacts, I started having one that would curl up after a few months and lose its shape. My doctor said is was due to that eye producing more protein than the other. I switched to disposable and didn't have the issue again, so I never followed up on how accurate that might be, but perhaps that could be a possibility?
posted by bizzyb at 1:50 PM on January 25, 2011

Which contact do you take out first? My right contact wears out quicker than my left. My doctor says it is because I take out my right one first, and invariably my fingers are slightly more dirty handling the right one than the left. By the time I get to the left one, the miniscule leftover dirt missed in the hand-washing has transferred to the right contact, but not the left. I alternate taking the left and right one out first, and that has helped.
posted by typewriter at 1:59 PM on January 25, 2011

I just went to my eye doctor last week with this same question, and didn't really get a very satisfying answer. My left eye has a very slight astigmatism, but it's so slight that for now both eye has the same prescription. So, all of my contacts are the same, regardless of which eye they go into.

She said that typically the contact degrades or gets gummed up because the eye is producing protein, but that there was no real reason for one eye to be more active than the other. I usually try to take mine out (both) as soon as I experience any blurring in my left eye and use only Clear Care solution (I had a LOT more trouble before using that brand).

So, no real great advice for you, but my eye doctor seemed to think it was a harmless mystery.
posted by DuckGirl at 3:33 PM on January 25, 2011

Response by poster: Thanks everyone for weighing in! It seems, based on personal accounts and maudlin's provided information, that this is indeed just the result of additional stress based on the toric lenses' positioning. I suppose we'll just have to buy more for one than the other.
posted by MangyCarface at 5:21 PM on January 25, 2011