What's Contact Lens Intolerance?

"Why do my contact lenses sting in my eyes when I put them in? They've been fine for years but in the last few days, when I put them in my eyes begin to really burn and get all bloodshot and watery!"
- Laura H.

Dear Laura,

It sounds like you may have developed Contact Lens Intolerance (CLI). CLI sufferers typically cannot apply a lens to their eye without feeling pain, stinging, or tearing up. Though you used to wear contact lenses all day, you now hesitate to use them even for the occasional social event.

CLI is a catch-all description of this eye condition where you simply cannot apply a lens to your eyes without pain. If you've been wearing contacts for years and are just now experiencing CLI, chances are you may have had a pre-existing dry eye condition exacerbated by contact lens use. "Individuals who become intolerant were probably borderline dry eye individuals who...as their tear volume decreased...became intolerant [to contacts], " says optometrist Edward S. Bennett, of the University of Missouri-St. Louis College of Optometry.

Another cause of Contact Lens Intolerance can be due to contact lens abuse. CLI from this doesn't happen quickly, but rather over the course of years usually. When patients first notice they are starting to develop a contact lens problem, they notice their contact lenses are starting to film up and feel dry at the very end of the day. Then, over the course of years, the patient starts to notice their contacts no longer feel comfortable mid afternoon and then gradually (over time) the comfort diminishes to the point that contact lens wear becomes intolerable.

What is Contact Lens Abuse?
Protein builds up on all contacts from the first time you put the lenses on your eyes. Even though a person cleans their lenses carefully every day after removal, protein penetrates the lens matrix. That protein is not just on the surface of the lens but inside the lens as well. At about 15 days out, the protein starts to denature (break down) and toxins are released. (If you have ever smelled a rotten egg or rotting meat, you are smelling denatured protein.) At that point the patient may notice that the lens no longer feels new, but patients often think it is not that troublesome.

The older the lens gets, the more protein denatures, the more toxins are released and the less comfortable the lenses become. Those toxins cause an inflammatory response of the eye, which in turn causes a change in tear chemistry, over time. When a person is young, the inflammatory response is fairly small and the eye recovers quickly, but as a patient persists in this type of abuse to their eyes, eventually the eyeballs revolt. The inflammatory response starts to make contact lens wear uncomfortable and it starts to affect the clarity of vision through the contacts.

The EVO ICL (EVO)
A potential option for people with Contact Lens Intolerance is the EVO ICL. CLI sufferers usually have dry eyes which may be exacerbated with procedures that require corneal reshaping like LASIK. Instead of needing to laser away eye tissue, the EVO ICL is a biocompatible, advanced lens placed inside the eye for vision correction. Additionally, the lens provides UV protection and can be removed if necessary.