Definition and Overview

Also referred to as Ortho-K, Orthokeratology is a nonsurgical procedure that uses gas permeable (GP) special lenses to gently reshape the corneas to treat different types of refractive errors (failure of the eyes to focus properly).

This is often confused with CRT (cornea reshaping therapy), which has the same principle as ortho-K. However, there are major differences. First, CRT is a patented method (Paragon), and only those who have been trained in the procedure and technology can perform CRT. Meanwhile, any doctor can offer other ortho-K-designed lenses.

CRT is also considered as the more advanced version of ortho-K, which has been around for more than 40 years. The lenses are FDA-approved and are more comfortable and safer to wear at night. They can also treat more severe cases of myopia and astigmatism than other ortho-K products.

Either way, ortho-K procedures use GP (gas permeable lenses), which are considered as better options than soft lenses. These types of lenses allow more oxygen to get into the eyes so they don’t easily develop an infection. The design also allows for a more comfortable wear. Unlike soft lenses, they are very durable.

Who Needs It and Expected Results

Gas permeable lenses are recommended for people who have refractive errors, especially myopia (with or without any degree of astigmatism). They are also ideal for children who have progressive myopia. Young adults also respond well to the treatment.

Patients who are adamant about undergoing refractive error surgeries such as LASIK are also great candidates for the procedure.

Many factors can affect the outcome of the procedure. While some people can already see clearly just days after the treatment, others need a few more. There are also times when the procedure does not work at all especially if the corneas are already too rigid, which means they are very difficult to reshape using only the contact lenses.

Orthokeratology has a higher success rate on moderate to severe myopia and astigmatism. However, the results are mixed when it comes to treating other refractive errors like presbyopia (blurry near vision due to old age) and hyperopia (farsightedness). Expectedly, those with only moderate or even less myopia respond a lot faster than the others.

The majority of users wear the specially designed GP lenses at night and corrective lenses during the day. As the condition improves, they may eventually get rid of the corrective lenses.

In the end, ortho-K provides more freedom to users, as they become less dependent on contact lenses and prescription glasses.

How Does the Procedure Work?

To understand how ortho-K helps, it’s best to know how the eyes work. The eyes are often compared to a camera since they’re responsible for producing images. To produce an image, however, light passes through the cornea, a very thin layer on the surface of the eye. It bends or refracts the light so it passes through the pupil. Around the pupil is the iris, which regulates the amount of light that goes in. From the pupil, light travels to the lens, which further bends the light, then to the retina, wherein the image appears inverted. Located at the back of the eye, the retina contains thousands of nerve cells, which deliver the signals to the brain, which then interprets the image. The shape of the cornea, therefore, can determine whether the image will appear distorted.

To create the necessary lens to correct the shape of the cornea (or flatten it), the optometrist will perform a series of tests. Usually, only those who have an otherwise healthy or good condition of the retina and other areas surrounding the eyes may be allowed to undergo the procedure.

If you are a possible candidate, the next test involves an instrument called topographer, which maps out every detail of the cornea. All your eye details from the tests including the eye topography will then be sent to the lab, which will develop the molds.

On your next appointment, the molds will be fitted. You will also be taught how to wear and maintain the lenses. You may also be requested to come back the next day to determine the initial effects of the lenses, when they are worn overnight. Remapping and refitting may also be carried out. All throughout the treatment, your progress and the health of the cornea will be monitored.

Possible Risks and Complications

Compared to surgery, ortho-K has fewer risks. GP lenses are also so much better than other types of corrective lenses. Nevertheless, some people complain of irritation, redness, inflammation, and infection, which usually occur when the lenses are not properly maintained.


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