Extending the life of your contact lenses is kind of like driving a car at 250 km per hour.  For a while, if everything goes smoothly, there is no indication of trouble.  However, if something starts to go wrong, it can go wrong in a major way very quickly. 

Some complications that can occur are:

• Allergic Reaction – protein build-up on the lens can cause discomfort, itchiness, dry eyes and intolerance to contact lens wear.
• Conjunctivitis – accumulated protein attracts bacteria which can easily lead to conjunctivitis.  Symptoms include redness, burning, itching, tearing, light sensitivity, blurred vision and mucous discharge.
• Corneal Edema (swelling) – Extended contact lens wear decreases the oxygen supply to the cornea and can cause increased fluid in the cornea. It can cause blurred vision and halos around lights.
• Neovascularization – The cornea normally doesn’t have any blood vessels. When it is deprived of oxygen (by over wearing contact lenses), the body responds by growing new blood vessels, hoping to increase oxygen to the cornea. This abnormal blood vessel growth can interfere with vision. The new vessels are also weak and can hemorrhage and cause blindness.
• Corneal Abrasion/Corneal Ulcer – Again, due to the lack of oxygen, the surface cells on the cornea become weak and easily damaged.  Corneal abrasions or corneal ulcers can form causing very serious infection and complications that can lead to blindness.

These complications can be caused both by wearing a contact lens too long in a day (or overnight) or by not replacing your lenses according to your optometrist's recommendations.  Either way, the eye is subject to less oxygen and more irritation and bacterial growth.  The blurred vision, pain, light sensitivity and potential scarring can be greatly reduced or eliminated by responsible contact lens wear.  If any of these symptoms occur, remove your contact lenses immediately and get checked by your optometrist.

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