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Eye Tests for Contact Lenses

Contact lenses are a great alternative to wearing glasses. Contact lenses offer a wide range of benefits and advantages over relying solely on glasses for clear vision. Each patient is different, with some patients wearing contact lenses only on weekends, special occasions or just for sports. That is the beauty of contact lens wear, the flexibility it gives each individual patient to decide how to optimise their lifestyle.

If you decide to opt for contact lens wear, it is very important that the lenses fit properly and comfortably and that you understand contact lens safety and hygiene. A contact lens test will include both a comprehensive eye test to check your overall eye health, your general vision prescription and then a contact lens consultation and measurement to determine the proper lens fit and which lens is the right choice for you.

The Importance of a Comprehensive Eye Test

Whether or not you have vision problems, it is important to have your eyes checked regularly to ensure they are healthy and that there are no signs of a developing eye condition. A comprehensive eye test will check the general health of your eyes as well as the quality of your vision. During this test the optometrist will determine your prescription for glasses, however this prescription alone is not sufficient for contact lenses. The optometrist may also check for any eye health issues that could interfere with the comfort and success of contact lens wear.

The Contact Lens Consultation

The contact lens industry is always developing new innovations to make contacts more comfortable, convenient and accessible. Therefore, one of the initial steps in a contact lens consultation is to discuss with your optometrist your lifestyle and range of activities you are involved in that could impact the type of contacts that suit you.

Some of the options to consider are whether you would prefer daily disposables or monthly disposable lenses, as well as soft versus rigid gas permeable (GP) lenses. If you have any particular eye conditions, such as astigmatism or dry eye syndrome, your optometrist might have specific recommendations for the right type or brand for your optimal comfort and vision needs.

Now is the time to tell your optometrist if you would like to consider coloured contact lenses as well. If you are over 40 and experience problems seeing small print, for which you need a specific optical prescription to see close objects, your optometrist may recommend multifocal lenses or a combination of multifocal and monovision lenses to correct your unique vision needs.

Contact Lens Fitting

One size does not fit all when it comes to contact lenses. Your optometrist will need to take specific measurements of your eyes to properly fit your contact lenses. Contact lenses that do not fit correctly could cause discomfort, blurry vision or even damage the eye. Here are some of the measurements your optometrist will take for a contact lens fitting:

Corneal Curvature

In order to assure that the fitting curve of the lens properly fits the curve of your eye, your optometrist will measure the curvature of the cornea or front surface of the eye. The curvature is measured with an instrument called a keratometer, this will determine the appropriate curve for your contact lenses. If you have astigmatism, the curvature of your cornea is not perfectly round and therefore a “toric” lens, which is designed specifically for an eye with astigmatism, could be needed to provide vision and lens fit. In certain cases your optometrist may decide to measure your cornea in greater detail with a 3D mapping of the corneal surface called corneal topography.

Pupil or Iris Size

Your optometrist may measure the size of your pupil or your iris (the coloured area of your eye) with an instrument called a biomicroscope or slit lamp or manually with a ruler or card. This measurement is especially important if you are considering specialised lenses such as Gas Permeable (GP) contacts.

Tear Film Evaluation

One of the most common problems affecting contact lens wear is dry eyes. If the lenses are not kept adequately hydrated and moist, they will become distorted, uncomfortable and your eyes will feel dry, irritated and itchy. Particularly if you have dry eye syndrome, your optometrist will want to make sure that you have a sufficient tear film to keep the lenses moist and comfortable, otherwise, contact lenses may not be a suitable vision option.

A tear film evaluation is performed by the optometrist by putting a drop of liquid fluorescein dye on your eye and then viewing your tears with a slit lamp or by placing a special strip of paper under the lid to absorb the tears to see how much moisture is produced. If your tear film is weak, your optometrist may recommend certain types of eye drops or contact lenses that are more successful in maintaining moisture.

Contact Lens Trial and Prescription

After deciding which pair of lenses could work with your eyes, the optometrist may have you try on a pair of lenses to confirm the fit and comfort before finalising and ordering your lenses. The optometrist or their staff will insert the lenses and keep them in for 15-20 minutes before the optometrist examines the fit, positioning, movement and your vision. If, after the fitting, the lenses appear to be a good fit, your optometrist can order the lenses for you. Your optometrist, or their staff, will also provide care and hygiene instructions including how to insert and remove your lenses, how long to wear them and how to store and clean them, if relevant.

Follow-up

Your optometrist may request that you schedule a follow-up appointment to check that your contact lenses are fitting properly and that your eyes are adjusting properly. Follow up consultations are are also vital to ensure your long term eye health and that the there are no affects on your eye health from your contact lenses, If you are experiencing discomfort or dryness in your eyes you should visit your optometrist as soon as possible as they may decide to try a different lens design, brand, a different contact lens disinfecting solution or to try an adjustment in your wearing schedule.