What causes dry eyes? It is estimated that approximately 10 million people in the United States suffer from dry eyes. They can be caused by aging, by problems with your tear ducts or eyelids, and even by some medications. What might surprise you, though, is that the leading cause of dry eyes is contact lenses. Scientific consideration of the contact lens, though, makes it clear why that would be the case. Consider the following facts:
- Contact lenses are manufactured of polymeric materials.
- Soft contacts are made from hydrophilic plastics that contain anywhere from 30 to 75 percent water. Contrary to what you might think, this does not help keep eyes hydrated- in fact, the more water a soft lens contains, the more prone it is to dehydration. As the moisture leaves the contact lens, it reacts by pulling water from the eye itself, causing the wearer to have the symptoms of dry eyes. This dehydration often occurs because of environmental factors, like exposure to smoke or heat.
- Rigid gas permeable lenses, by contrast, do not contain any water at all. The polymer in these lenses is “hydrophobic”, and actually repels water, making them less compatible with the tear film of the eye.
- Contact lenses can chafe the surface of the eye. The outer layer of the cornea, the epithelium, has microscopic hairlike structures, and years of contact lens use can actually slough off these delicate cells, resulting in poor tear film stability. Rigid gas permeable lenses are more likely to cause this problem than soft lenses, but it can be an issue with both types of contact lens.
Dry eyes can often be minimized or eliminated by changing lens materials and/or water content of the soft contact lenses. There are several dry eye contact lenses on the market, and they can really expand the length of time contact lenses can comfortably be worn. There are also artificial tears and eye drops, though these only provide temporary relief. A more permanent solution is surgery to alleviate the dry eye condition, through the modification of the tear drainage system.
Of course, another option is to eliminate the need for contact lenses entirely, through LASIK. If you suffer from dry eyes, the best idea is to contact your ophthalmologist to discuss your options and decide on the best course of action.