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Orthokeratology, also called ortho-k, is a method of correcting vision […]

By Published On: 9 July 20123.2 min read

Orthokeratology, also called ortho-k, is a method of correcting vision problems which involves the use of specially designed rigid gas permeable (RGP) contact lenses. The lenses are designed to alter the shape of the cornea or the transparent front part of the eye. They are worn nightly or every other night and are removed in the morning. Clear vision will be observed throughout the day without using eye glasses or contact lenses.  Orthokeratology reduces or corrects low levels of shortsightedness and astigmatism.

How safe is ortho-k?

Here are some safety considerations you should know before going for orthokeratology:


Vertical and lateral centrations of the RGP lenses are essential in orthokeratology. If there is no proper centration, the visual acuity will not be optimal because the treatment zone will not be centered on the pupil and optical axis of the eye.

To ensure proper centration, see you eye doctor within several hours from waking up on the morning after your first overnight use of the lens. He will observe the fit of the lens, its movement, your visual acuity and corneal topography.

Adherence or Binding

Adherence of the lenses is a possibility in orthokeratology because of the use of a large diameter shaping lens overnight. To avoid binding, you should do the following:

•    Before you sleep, put several drops of the recommended wetting or rewetting solution in each eye.

•    Once you wake up, put several more drops of the solution in each eye. In the alternative, you may opt not to remove the lenses immediately upon waking up. The installation of drops coupled with a few minutes of blinking will likely cause the adhered lens to move spontaneously.

•    Ask your optometrist for instructions on how to determine if your lens is bound and how to loosen it manually.

•    If your lenses do not move freely after 30 minutes from performing the above-mentioned steps, contact your optometrist immediately.

Corneal Staining

Ortho-k may not be advisable if you produce insufficient amount of tears or if the tears you produce are not of good quality. Otherwise, you may be at risk of corneal staining. If you are suffering from the above-mentioned conditions, you should discuss your options with your optometrist.

Dimple Veiling

Dimple veiling is the fluorescein staining of indentations in the epithelium caused by air bubbles between the cornea and the RGP lens.

This happens when the base curve, depth of the reverse or the reservoir curve is too steep.

It is not a serious problem but should be corrected as it likely that the fitting relationship of the contact lens to the eye is not ideal.

The indentations have been shown over the years to not cause any short or long term health issues and tend to resolve very quickly if the lenses are discontinued or if lenses are refitted more accurately.

What can be an issue is if the dimple veiling occurs over the pupil where the vision comes from.  Luckily in orthokeratology this is very rarely an issue as the contact lens typically is fairly close to the cornea in this area.

Other Complications

Here are some other eye complications that may occur when you go for orthokeratology. These are often associated with lack of patient education and/or failure to comply with proper wearing and caring instructions.

•    Irritation or infection.
•    Corneal edema.
•    Extreme discomfort.
•    Redness.
•    Tearing.
•    Discharge.
•    Corneal abrasion.
•    Distortion of vision.
•    Corneal scarring.
•    Decreased vision.
•    Corneal ulcer.
•    Iritis.
•    Neovascularization.

Should you experience any of the above, remove your lenses and contact your optometrist immediately. Never reinsert your orthokeratology lenses while the symptoms exist and without your doctor’s go signal.

At The Eye Practice we have been performing Orthokeratology procedures since 1995.  Our skills have developed with the technology.

If you are interested in ortho k, or are already doing the procedure and are having trouble, call us on (02) 9290 1899 or book online.


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