The above photos demonstrate blood vessels growing in to the cornea on a patient who wears their contact lenses every waking hour. You can see the redness also around the cornea/conjunctiva margin. These blood vessels grow because of decreased oxygen getting to the cornea. The body tries to compensate by growing blood vessels.
Unfortunately increased blood vessels to the cornea result in increased risk of future immune responses (episodes of redness, pain, inflammation, swelling, light sensitivity, and decreased vision) and also indicate an increased risk for severe corneal infection. These can result in corneal ulcers where the bacteria actually eat away at the cornea. These ulcers are treated aggressively to prevent loss of the eye or loss of vision . They result in permanent scars that, if located centrally, sometimes require a corneal transplant.
I refit this patient in to a lens that breathes about 5 times more oxygen than the standard contact lens. Even so, it is recommended that patients give their eyes a rest from their contact lenses a few hours in the evening and maybe a day or two during the week when possible. LASIK is actually less risky than continuing to wear the same lens the same amount of time.
It is tempting for contact lens patients to overwear their contact lenses either to save money or because of convenience. There are many people who get away with it without insult. However, when serious problems occur, it is almost invariably in those patients who overwear their contact lenses. Either they wear them from the time they get up to the time they go to bed every day, or they sleep in them on a regular basis, or they don’t replace them when they’re supposed to, or they don’t replace their case when they should . Rarely do these individuals have a good pair of glasses that they like.