Every year, more and more people make the transition from prescription eyeglasses to contact lenses. Contact lens technology has advanced significantly in the last few decades, and there is a lens design that can fit the needs of virtually everyone. Making the switch from eyeglasses to contact lenses requires a comprehensive eye exam as well as a contact lens exam and fitting.
What is a contact lens exam?
Contact lens exams are different from regular eye exams. A comprehensive eye examination will include visual acuity testing with an eye chart, as well as eye health tests and a refractive error test. If you are making the switch to contact lenses, your doctor will complete the standard eye and vision testing then begin to gather additional information about your lifestyle and preferences when it comes to contact lenses. A contact lens fitting will follow the exam and discussion.
Reasons for contact lens exams
Contact lenses are not one size fits all. If a contact lens is too steep or too curved, it can cause significant eyestrain, discomfort, and damage. That is why it is important for patients to undergo a comprehensive contact lens exam and fitting.
Performing contact lens exams
The goal of a contact lens exam and fitting is to determine the best contact lens style and size to fit your eyes. The contact lens exam includes the following measurements:
Corneal curvature: the curve of the cornea is measured with a keratometer. This measurement dictates the best shape and diameter for your contact lenses. Corneal curvature measurements may be combined with aberrometer measurements to identify higher order visual aberrations.
Eye surface irregularities: The exam may reveal that your eye's surface is irregular due to astigmatism. Patients with astigmatism are given a special type of contact lens known as a toric lens, which is shaped to offset the abnormalities.
Pupil and iris size: Pupil and iris measurements are taken with an instrument called a biomicroscope. These measurements are used to help choose the proper size and orientation of contact lenses.
Tear film testing: Tear film testing is conducted to ensure that your eyes are capable of keeping contact lenses moist with tears. Tear production can be evaluated with a slit-lamp test or with a small paper strip placed under the lower eyelid.
If you are considering contact lenses, schedule an appointment with an experienced optometrist.