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Posted on 04-25-2016

A comment that I hear on a daily basis as an eye doctor is, “I can keep wearing my contacts for several months before they start to feel bad!” A comment that I hear on a daily basis as an eye doctor is, “I can keep wearing my contacts for several months before they start to feel bad!” I love that many of my patients are so honest with me because it gives me the opportunity to teach them about why they should never stretch their contact lenses. So why are some contact lenses daily, bi-weekly or monthly replacement and, more importantly, why is it critically important to change them regularly? I’m glad you asked!


Contact lenses sit on the part of the eye called the cornea. The cornea is the clearest tissue found in nature because light has to be able to pass through it to get to the brain, which is vitally important to creating sight. Just like you would rather not look through a pair of smudgy glasses or a dirty windshield, your corneas need to stay crystal clear to give you great vision. One of the reasons the cornea is so clear is because they don’t contain blood vessels. Instead, oxygen, water, and nutrients are supplied to the cornea through the air and the tears. When ANY contact lens is placed on the eye for any amount of time, the cornea receives dramatically lower amounts of these nutrients. Because of this it is important that your eye doctors carefully manage the use of contacts on a yearly basis.

The amount of time that you can wear your lenses before tossing them out has nothing to do with the comfort of the lens. In fact, your contacts should remain comfortable the entire time if you wear them properly. Contacts have pores built in that allow an ‘acceptable’ amount of oxygen and nutrients to pass through to the cornea during it’s recommended wear-time. The amount of nutrients that are allowed to pass through depend on the way the lenses fit the eye, the material the lens is made of, the amount of prescription in the lens, and wearing/disposal schedule of that particular contact lens. I evaluate and decide most of these factors for the patient however, the responsibility to follow your schedule is up to you, the patient. 


    The issue is those pores get clogged with sweat, dust, debris, makeup, etc; this will not only decrease the cornea’s ability to breathe, but also provides a great place for bacteria to call home! The wear time is decided after years of research and with the help of the FDA to determine how long these lenses can be worn safely. All contacts permit less oxygen to reach the eye in comparison to not wearing contacts at all but this is not a problem as long as (in the case of a monthly lens) the lenses are worn for 30 days or less and the patient regularly sees their optometrist. After 30 days, the amount of oxygen that reaches the cornea is lower than the cornea needs to stay clear and healthy. 

Wearing a contact lens too long may cause mild cosmetic issues, like red eyes, as well as dryness and irritation. Nevertheless, more serious problems tend to develop in time, such as bacterial infections and painful ulcers (holes in the cornea). When there is a lack of oxygen, inflammatory cells called “subepithelial infiltrates” begin to appear in the layers of the cornea, interrupting the sensitive corneal nerves. These are highly uncomfortable and can lead to more serious issues. Overwear can lead to a serious inflammation inside the eye called uveitis. A very common long term effect of corneal ‘suffocation’ is when the brain sends a signal to the eye that causes the development of blood vessel in the cornea which are permanent and sight threatening. When we start to see these vessels grow to a certain point, we will tearfully have to discontinue prescribing contacts for you and you are no longer a candidate for the LASIK surgery that you have been saving up for.

All of these problems are avoidable! By wearing your contacts lenses for the prescribed schedule, the risk of getting these issues are pretty low. It is also important to have your eyes evaluated at least once a year by your optometrist so that we can treat any impending problems accordingly. It’s our job to ensure that your eyes aren’t showing any signs of being “angry” with the lenses or corneal suffocation. Think of your contacts as a pair of muddy, moldy socks and mark your calendar or set an alarm for when it is time to replace them. Don’t think of it as a waste because you had to throw them away before they were uncomfortable. It is more of a waste to put a lifetime of great healthy vision at risk for a dirty piece of plastic. Like I always say: you can buy a million replacement contacts, but you only have two eyes. Take care of them because they cannot be replaced!

Please feel free to send an email if you have any questions or concerns.

Nytarsha Thomas, O.D.


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