MODEL RELEASED. Eye examination. Image 11 of 15. Ophthalmologist selecting contact lenses for a patient to try, following an eye examination. Contact lenses are an alternative to glasses. They are placed over the cornea of the eye, where they alter the path of light to correct defective vision. They can be worn daily or monthly and can be disposable, depending on the make. An eye examination not only identifies sight deterioration, it can also reveal underlying health problems such as high blood pressure or diabetes. A healthy individual should have an eye test every two years. See M450/267-281 for an eye examination.