Importance of Correct Measuring and Fitting of Contact Lens

Contact lens can be able to improve your vision and make you feel great. But having contact lens fitted is far more complex than getting eyeglasses. The prescription you receive at the end of an exam is most likely, a prescription for your glasses only. Precise prescription for your contact lens can only be issued after you undergo several steps that are not incorporated in eye exams.

As the contact lens sit directly on the cornea, it is important that the contact lens is the correct measurement for your eyes.

Contact Lens Fitting

If you are having thoughts of switching to contact lens, if you want your contact lens prescription updated or you are considering wearing color contact lens for cosmetic purposes then it is very essential that you mention this to your next appointment to your ophthalmologist. By doing this, you are sure that there is enough length of time given for your eye doctor to have extra time required to be able to perform special exams and discuss the available options with you. This will not only ensure clear vision but also a correct, proper and comfortable contact lens fitting.

How to choose the appropriate contact lens?

Just like any eye exam, your visual acuity (ability to identify letters at a distance) will be checked one eye at a time using an eye chart. Tests will also be done to check other vision and eye health troubles. After doing this, if your eye doctor has decided that it is safe for you to wear contact lens; he/she will need some additional information to help you choose the right contact lens (e.g. if you have an eye condition which would benefit from silicone hydrogel contact lenses, then this option will also be measured).

Age is very much important too, since people who are 40 years old and above has the tendency of developing presbyopia (causing near vision to get worse due to the loss of flexibility of the natural lenses in your eye) which may influence whether you will need mutlifocal or monovision contact lenses.

All these considerations should be well thought of since your quality of life will most likely be affected by the choices you create.

Cornea Measurement

The application of "one-size fits all" may apply to many things, but certainly not when it comes to contact lens. Your eyes must be measured to ensure the right contact lens for you. This involves special measurements of the curvature of the front surface area of your eye using a device called keratometer. It analyzes light reflections from the cornea and based on that will determine the curvature of your eye and the size of the contact lens which you will need. For people who have hard-to-fit corneas, corneal topography (computerized measurement) can be taken in order to get the accurate shape of the corneal surface.

Extra Measurement and Testing for contact lens fitting

For a good fit, the size of your pupil should be measured. This can be taken by using a ruler or an automated instrument. Also, the diameter of your iris is also needed for proper sizing.

Methods:

1. Tear film evaluation can also be taken. This is done by inserting a small strip of paper under the lower eyelid, closing your eyes for several minutes then the paper is removed. Tear film evaluation is done in order to know your tear reproduction and if you have dry eyes.
2. Usage of fluorescein dye (in eye drops) to know how long tears disperse.

Correct Contact Lens Fitting

Next, biomicroscope can also be applied to the eyes which give an intensively magnified view of the cornea which allows the doctor to see the fit of the trial contact lens and how much they move with each blink. It can also be used to evaluate the health of the cornea and any changes after contact lens wear.

If trail lenses are worn, one must wear it for at least 15 minutes in order for them to settle and the natural tearing to stop. Afterwards, your eye doctor will examine and evaluate your eye and the fit.

Follow-up Exams and Replacement of Contact Lens

After you fit your contact lenses (which likely takes about 2-4 visits to your eye doctor), one must have his/her eyes and contact lens examined once every year. An annual exam by your eye doctor is important to maintain the health of your eyes as well as to avoid any complications.

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