Contact lenses are an option for people who need a prescription for better vision but do not want to rely on eyeglasses every day. However, contact lenses require more than the prescription for correcting vision. The eye doctor must also measure the shape of the eye in order to prescribe the proper fit of lenses. A person should know the effects of wearing the wrong contact lenses to help her watch for signs that she may have the wrong prescription.
One of the most common effects of wearing the wrong contact lens prescription is blurry vision. Since contacts are meant to improve vision, the wrong prescription will typically cause impairment in a person’s vision, says the U.S. Food and Drug Administration. In some cases, a person with poor vision may notice a slight improvement in vision, even with the incorrect prescription. However, vision will not be clear. Wearing the incorrect vision prescription will not cause vision to worsen, but a person may experience eye strain and headaches as an effect of the wrong prescription.
The front of the eye, called the cornea, may have a slightly different shape for many people. Wearing the wrong prescription contact lens may feel uncomfortable, reports “The Merck Manual for Healthcare Professionals.” Also, the ill-fitting lens may move around on the eye, possibly scratching the eye’s surface. If the lens fits too tightly over the cornea, the cornea may not receive nourishment from the tears in the eye. The tears provide a film that coats the eye’s surface. This helps to keep the eye comfortable and vision clear. A tight-fitting lens may lessen or eliminate the amount of tears under the lens, causing irritation and blurry vision. Extended use may eventually lead to a corneal infection.
Corneal ulcers may also result from wearing an incorrect prescription, says the U.S. Food and Drug Administration. A corneal ulcer is an infection of the cornea, and will typically cause severe eye pain, tearing and light sensitivity. If a person experiences these symptoms, she should stop wearing the contact lenses and seek an evaluation from an eye doctor. The doctor may prescribe one or more eye drops to treat the infection. However, if a person does not seek treatment, she may experience permanent scarring of the cornea, and this will likely result in vision changes.