The question of whether to wear contact lenses to an eye exam depends on the appointment’s two distinct goals: determining the correct vision prescription and assessing eye health. A comprehensive eye exam measures visual acuity for glasses, while a contact lens examination evaluates how the lenses interact with your eyes. The best approach is usually to arrive wearing your lenses so the doctor can observe the fit first. However, you must be prepared to remove them later for the core measurements.
Why Your Eyes Need to Be Bare
The determination of your precise vision correction, known as refraction, requires your eyes to be in their most natural state. Contact lenses, even soft ones, can temporarily reshape the cornea, which is the clear, dome-shaped front surface of the eye. This slight alteration in corneal curvature can interfere with the accurate reading of your refractive error. Wearing lenses can also affect the stability of the tear film, which is the thin layer of fluid covering the eye. An unstable or altered tear film can distort the measurements taken by instruments like the corneal topographer and the autorefractor, leading to a prescription that is not entirely correct.
To ensure accurate measurements, you must remove your contacts before the main testing begins. For soft lenses, eye care professionals typically recommend removing them at least two hours before the appointment. Patients who wear rigid gas-permeable lenses (RGPs) may need to stop wearing them for a few days or even weeks, as RGPs exert more pressure and cause more significant corneal changes. This removal time allows the cornea to recover its natural curvature and the tear film to stabilize. A precise glasses prescription is a fundamental measurement because the contact lens prescription is derived from this baseline.
Assessing Contact Lens Fit and Wear
The second stage of the contact lens evaluation focuses on the physical relationship between the lens and the eye’s surface. This requires the lenses to be in place so the doctor can observe their performance. The optometrist uses a specialized microscope called a slit lamp to examine the eye and the lens under high magnification.
The doctor assesses the lens movement, looking for proper “lag” or slide on the eye with each blink, which is necessary for tear exchange beneath the lens. Insufficient movement can lead to oxygen deprivation, while excessive movement can cause discomfort and blurry vision. The slit lamp also allows for a detailed inspection of the cornea and conjunctiva for any signs of irritation, inflammation, or corneal staining caused by the lens.
The eye care professional evaluates the lens coverage, ensuring the lens fully covers the cornea and that the edges do not press too tightly or stand too far off the eye’s surface. They may use a special dye, fluorescein, to highlight the tear film and check for any areas of damage on the cornea that the lens might be causing. Observing the lens while it is being worn is the only way to ensure the fit is safe and comfortable for long-term use.
Practical Steps Before the Appointment
To ensure a smooth visit, you must bring a contact lens case and fresh solution with you to store your lenses after the initial assessment. Having your current eyeglasses available is also important so you can wear them comfortably after removing your contacts and during any dilation procedures. Bring your current contact lens boxes or prescription information, including the brand name, base curve, and diameter of your lenses. Be prepared to discuss your typical wearing schedule and any concerns about comfort, dryness, or vision quality with your current lenses.