Causes Of Redness and Irritation With Contact Lenses

By Scott Burge, OD

Maryland Eye Associates

. http://marylandeyeassociates.com

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Causes Of Redness and Irritation With Contact Lenses

Many people wear contact lenses instead of eyeglasses for a natural appearance and because of the misconception that they do not look good in glasses. If contact lenses are the preferred modality, then having red, irritated eyes while wearing them can be problematic and disappointing. The causes of redness and irritation while wearing contacts are typically issues of lens fit, lens material, solution toxicity and overwear/wearer abuse.

Contact lens fit is a function of having the ideal relationship between corneal curvature and the “base curve” of the lens. Corneas are not “one size fits all.” A base curve that is too flat (loose) can result in excessive lens movement, lens decentering as well as lens edge curling or “fluting.” The combination of these results in improper corneal wetting from the natural tear film during and between blinks. A base curve that is too steep (tight) can result in lens adherence which in turn blocks tear exchange under the lens, reduces oxygen supply to the cornea and leaves the wearer with an imprint of the peripheral lens curve on the conjunctiva after the lens is removed.

Material issues are a function of the lens “plastic” and it's oxygen permeability or “breathability.” Wearing the most breathable material sounds like a straightforward and obvious choice. However, on some eyes, the most breathable material may not “wet” well. It can also be highly prone to deposit build up. The result from this is a “dry eye” while wearing lenses. Although there are plenty of natural tears present, a less than ideal material for the specific patient will result in lens dehydration leading to lens adherence and subsequent irritation.

Most newer design lenses today have a silicone material component referred to as “silicone hydrogel.” One material type does not work for all wearers. Newer is not always better. Some wearers are better off in an older non-silicone plastic, which has a corresponding lower oxygen permeability rating.

Contact lens solution toxicity is a well-recognized problem. While it is easy to understand that chemicals in contact lens solutions can be a source of irritation, sorting through the various products available for lens wearers can be confusing. With the exception of daily disposable lenses, which require no supplementary solutions, all reusable lenses require some form of “disinfecting” solution, commonly referred to as “multipurpose” solution. Multipurpose solutions have a combination of anti-bacterial and cleaning ingredients, all of which end up on the eye.

While formulated to be compatible with the eye, for wearers who are sensitive, multipurpose solutions result in a “textbook” allergic/toxic appearance of conjunctival infection. The eye is red, typically in a circular pattern adjacent to and around the cornea. The degree of redness will be mild to severe depending on how long the offending solution has been in use. With repeated exposure, the allergic/toxic response becomes worse.

Additionally, lenses that have been in use for weeks or months increasingly absorb the chemicals they are soaked in, which in turn compounds the source of irritation. The wearer needs to change solution and start with a new pair of lenses. For some, it is necessary to change solution category from multipurpose to hydrogen peroxide with saline rinse.

Overwear and wearer abuse includes failure to replace lenses as directed. As lens material ages, it dehydrates and the fit of the lens becomes “tighter.” Lenses in use for too long do not wet well because of surface deposits and protein film. Sleeping with lenses intended for daily wear only compounds all of these problems.