Contact lenses have many benefits, including the ability to engage in physical activity without worrying about eyeglass frame or lens damage, and a more fashionable appearance to the face. There are many contact lens wearers in the United States that are able to wear them for many years without trouble. There are some conditions, however, that can arise after several years of contact lens use. Most of these conditions relate to oxygen deprivation or hygiene issues, both of which are preventable by responsible use and proper lens maintenance.
Corneal Ulcers
According to HealthScout, corneal ulcers are a potentially blinding condition that can result from contact lens use, affecting 12,000 people each year in the United States. It occurs more commonly in contact lens wearers who leave them in for an extended period of time. In addition to prolonged wear times, factors that contribute to corneal ulcers in contact lens wearers include poor cleaning habits, lack of hygiene, and dry eye syndrome.
Reduced Oxygen Intake
The article "Effects of long-tem extended contact lens wear on the human cornea" by Holden, Sweeny, et. al in "Investigative Opthamology & Visual Science" reports several adverse effects from long-term contact lens use. Patients they observed wore contacts for an average of five years, and results show they suffered from a nearly 15 percent reduction in oxygen uptake by the cornea. Oxygen is necessary for the proper functioning of the eye. Fortunately, after approximately one month of discontinuing contact lens use, the oxygen uptake of the eye recovered. The study recommends the use of thinner lenses that are more frequently removed and replaced.
Neovascularization
Neovascularization refers to the formation of new blood vessels in the eye due to chronic corneal hypoxia (oxygen deprivation). In his paper entitled "Contact Lens Complications & Management," Kelechi Mezu-Nuabue, O.D., says some wearers of contacts may have chronically low oxygen levels, so the eye compensates by forming new blood vessels to deliver the needed oxygen and nutrients. This condition can be treated by switching to a different lens, such as rigid gas permeable (RGP) contacts, or by wearing the contacts for less time.
