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Home » Contact Lens Fitting Q&A with Dr. Drake

Contact Lens Fitting Q&A with Dr. Drake

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 comprehensive wellness exam, which potentially includes a prescription for glasses, entails examining the health of the entire eye. This may include dilating the eyes. It also includes evaluating the behavior in which the eyes focus and work in concert together. An exam for contact lens wearers or new wearers of contacts includes all of the above, plus an evaluation of the way the contact lens centers and moves on the eye and how it affects or has potential to affect the health of the eyes, and of course, the ability to grant its wearer the best possible vision. A contact lens exam often includes one or more follow-up appointments made for contact lens wearers to ensure the contact lens doesn’t cause any eye health problems that may develop over time. The contact lens prescription will then be finalized.

 

Q: What can be expected during a contact lens fitting?
A: A contact lens fitting entails evaluating the lenses on the eye for the best health and vision. A measurement of the corneas’ curvatures is done which may include a corneal mapping; a biomicroscope is used to evaluate the anterior surface eye health and the lens performance while on the eye. The final prescription ultimately needs to be finalized. Regularly, the contact lens prescription will vary from the same person’s eyeglass prescription; the difference is due to the contact lens sitting directly on the eyes, while glasses sit a distance from the eyes.

 

Q: What are contact lens measurements? How are they determined? Does it change if a patient has astigmatism?
A: Contact lens measurements are the diameter and base curve of the lenses. Soft lenses also are made of different materials, thicknesses, water content, base curves, diameters and oxygen permeability. The curvature of the cornea and the patient’s eye health determines the initial lens trial fit. Changes are made depending on how the lenses perform on the eye. Specialty lenses such as rigid gas permeable lenses and scleral lenses have many more parameters which include special curvatures and diameters. A contact lens prescription for astigmatism may be recommended depending on the patient’s amount of astigmatism and if it is due to the eye having corneal or lens astigmatism, or both. If needed, contact lenses with astigmatism correction are more sophisticated because they add a second prescription (the astigmatism) at a certain axis and are usually weighted to align correctly on the eye.

 

Q: What kind of instruments and tests can I expect to see during a contact lens exam?
A: In addition to the instruments used in a comprehensive eye health examination, a keratometer will be used which measures the curvature of the cornea. A mapping instrument will also be used to see what areas of the cornea are more and less elevated. Finally, a slit lamp biomicroscope will be used to determine how the lenses move and center on the eye, and how the eye reacts with the lenses on.

 

Q: What are trial lenses?
A: Trial lenses are sample lenses doctors typically carry in the office to assist in determining the right contact lens for the eyes. Because not every prescription in every lens is stocked in practices, some trials lenses may have to be ordered.

 

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: Sometimes one visit will allow the doctor and patient to determine the right lens. Many other times it takes trying different lenses and some passage of time, depending on the eyes and prescription. It may take longer periods for certain eyes, depending on how the eyes react, the comfort and vision and the type of lens needed to be fit.

 

Q: Why does a contact lens exam cost more than an eyeglass eye exam?
A: The cost differential is attributed to the additional tests, professional expertise, type of lenses needed to be determined and extra visits.

 

Q: What are some advantages and disadvantages of contact lenses?
A: Advantages: Better natural and peripheral vision, the ability to wear non-prescription sunglasses, no fogging of glasses.
Disadvantages: Care, discomfort for drier eyes, increased risk of infections and inflammation, etc.

 

Q: How does an eye doctor determine which contact lens brand to recommend to a patient?
A: This depends on the history and needs of the patient.
Q: Whether to use daily contacts or reusable?
A: Daily disposables are the healthiest disposable lens due to having a fresh, clean lens every day. When possible, we recommend those over other disposables. Daily or single use disposables are usually recommended for people with allergies.

 

Q: Are contact lenses for everyone?
A: Not everyone can wear contacts. Sometimes this is prevented due to the prescription amount, dry eyes, different anatomy, eye diseases or other factors.

 

Q: Are there special contact lenses for dry eye? Astigmatism?
A: There are some materials and contact lens solutions that may work better for dry eyes. There are special contacts for astigmatism. There are also special contact lenses for keratoconus, post-surgical corneas, odd shaped pupils, light sensitivity and other issues.