Home » Contact Lens Fitting Q&A with Dr. John Stewart

Contact Lens Fitting Q&A with Dr. John Stewart

Q. What is the difference between an eye exam geared towards wearers of glasses and an eye exam geared towards wearers of contact lens?

A. A contact lens exam requires special considerations as compared to a glasses exam. Additional measurements of the cornea are critical for a good fitting relationship between the cornea and the contact lenses. If the contact lens fits too tightly, the cornea can develop abrasions on its surface. The cornea’s nerves can become inflamed and great discomfort will result. If the contact lens fits too loose, the contact can fall off of the eye. An individual needs to be able to insert and remove the contact lenses without causing injury to the cornea or the contact lens. Our Practice provides additional training for patients who have trouble handling their contacts. Each and every time a contact is removed, it must be cleaned and disinfected before it is reinserted or a corneal infection can result by bacteria or fungus. We provide training and review with the proper procedures to clean and disinfect contacts.

Q. What can be expected during a contact lens fitting?

A. A patient can expect to have a different experience when having a contact lens fitting. In addition to the eyeglass exam, questions will be asked to determine which contact lens will work best for them. Will they want to leave the lenses in their eyes overnight or will they remove them every day? Will they wear them only occasionally or will they be for everyday use? Do they want a contact lens that they throw away every day or do they want a contact lens that they have to clean and disinfect? If the patient is over age 40 and has a compromised ability to see up close, how will they see up close with their contact lenses? Will they wear readers over their distant contacts, or will they wear multifocal contacts, or will they wear monovision?

Q. What are contact lens measurements? How is that determined? Does it change if a patient has astigmatism?

A. The contact lens measurements are called the parameters. The measurement comes from the refraction and keratometry. A good refraction is required to give a contact lens wearer the best vision both day and night. Astigmatism can be significant enough to require astigmatism correction in contacts. Another name for astigmatism contacts is called torics which is short for toricity. The relationship between the refraction and keratometry is determined by the optometrist to choose a spherical contact or a toric contact. The keratometry helps determine astigmatism and the vaulting of the contact. The shape of the cornea and the shape of the contact must match and be close to a parallel relation for the contact to provide good comfort and vision without harming the cornea.

Q. What kind of instruments and tests can I expect to see during a contact lens exam?

A. We will begin the tests of a contact lens exam by using an autorefractor and phoropter to determine your best corrected visual acuity. Along with your updated prescription, we will measure the shape of your cornea with an autokeratometer. The shape of your cornea will determine the vaulting of the contact. We then use biomicroscopy to analyze the fitting relationship of the contact on your eye.

Q. What are trial lenses? How can an eye doctor best determine the right contact lens prescription?

A. Trial lenses are a great way to find out if the contact that you will be wearing is right for you. After we have completed measuring your new prescription and determining the shape of your cornea, and we will have information from you regarding how you want to wear and care for your contacts, we will sample you a pair of contacts that we call trials. They are for you to try before you purchase your contact lens prescription.

Q. Will I know right away if the contact lenses fit or is that something that can only be felt with the passage of time?

A. You will know right away or within the next few days whether your contacts fit and provide good vision. We will check your new contacts that are on your eyes in our office for vision and comfort using our electronic charts and biomicroscopy. You will see and feel for yourself how you like your new contacts when you leave our office and experience your new vision.

Q. Why does a contact lens exam cost more than an eyeglass eye exam?

A. A contact lens exam costs more than a glasses exam because more considerations and time are involved. When we have a corrective lens for your vision on your eye, we have to take into account the prescription change from the spectacle plane to the surface of the cornea. If we use the same prescription as the glasses the vision can be either too strong or too weak resulting in blurred vision and migraine headaches. The fitting relationship of the contact and your cornea must be taken into account or the lens may be either too tight or too loose resulting in complications of pathology and blurred vision. Ensuring proper insertion and removal of the contact is imperative for the patient, otherwise, basic insertion and removal can cause great injury and harm to their eyes. It is also important for the a patient to know how to perform proper cleaning and disinfection lest a contact lens infection can develop

Q. What are some advantages and disadvantages of contact lenses?

A. There are many advantages for wearing contacts. An important study from The Ohio State School of Optometry of school-age patients improved their self-esteem. Contacts are good for sports and recreation. A patient’s side or peripheral vision is improved that helps them with their reaction time. When contacts are worn, regular sunglasses can be worn over contacts for various activities instead of expensive prescription sunglasses. Eye color can be changed with contacts. Contacts can improve a person’s appearance. Of course, there are potential disadvantages to wearing contacts. Contacts are classified as a class 2 ophthalmic medical device by the FDA. Contacts can cause great harm if worn and cared for improperly resulting in infection and, in rare and extreme cases, even blindness.

Q. How does an eye doctor determine which contact lens brand to recommend to a patient? Whether to use daily contacts or reusable?

A. The Eye Doctor determines the contact lens brand that’s best for the patient during the contact lens fitting. After measuring the patient’s vision, contact lens materials and parameters are considered to provide the patient their contact lens prescription. Matching the patient to the right contact will greatly determine success. Whether the patient will wear contacts on occasion or every day can make the difference between choosing a daily wear contact or a monthly wear contact. If a patient travels frequently, choosing a daily wear contact is very convenient. There is no cleaning required with daily wear contacts. They are considered single use. Every day the patient has a great experience wearing a daily contact because it is brand new. There is no cleaning required because they get thrown away at the end of the day. Monthly replacement contacts require cleaning and disinfection each and every time they are removed. The cost of the solutions and the patient’s time added to the cost of the monthly contacts are not much less than the cost of the daily contacts.

Q. Are contact lenses for everyone?

A. If a patient is motivated to wear contacts, there is a contact that they can wear. Patients in their youth or adult age who have myopia, hyperopia, astigmatism, presbyopia, or any combination can wear contacts. A patient may want to have better vision than glasses when they play sports and recreation. They may want to change their appearance and not be seen wearing glasses. They may want to be able to wear regular sunglasses. They may want to see better up close without having to wear bifocal glasses. They may want to prefer contacts because they have sinus pressure and wearing glasses bothers them.

Q. Are there special contact lenses for dry eye? Astigmatism? Insert other eye problem?

A. Patients who have dry eyes, astigmatism, and presbyopia present special challenges for wearing contacts. Eye drops are available over the counter without prescription and at the pharmacy with a prescription that can help improve dry eyes, however, the new contact lenses now have moisture in them. It’s not so important to add drops to improve contact lens comfort. Dry eye patients can now wear contacts for a good long day without having to put drops in their eyes. Astigmatism contacts can greatly improve distant and night time vision. Blurred vision results when astigmatism is only corrected with regular spherical contacts. Presbyopia occurs starting around age 40 and increases up to age 50. Up close vision becomes blurred and becomes clear when held at arm’s length. Multifocal contacts work better than bifocal glasses because near vision is improved in all directions of gaze. With bifocal glasses, the up-close vision is only improved in downgaze.