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What Are Orthokeratology Lenses And Who Is A Candidate?

Ortho what? Unless you are already using ortho-k lenses, there's a good chance you have never heard of them, so let's take a look at what they are first. 

Orthokeratology, which is often shortened to "ortho-k", is a non-surgical treatment, delivered in the form of special contact lenses, that temporarily corrects the shape of the cornea, the transparent layer that covers your eyes. These lenses, worn overnight, gradually improve your vision. Ortho-k lenses, also known as corneal refractive treatment and overnight vision correction, can be used to correct:

  • Myopia (nearsightedness)
  • Hyperopia (farsightedness)
  • Astigmatism (which can cause blurry vision at any distance)

Ortho-k lenses are most suitable for people with prescriptions ranging from -6 to +3 and mild astigmatism (a maximum of -1.75 diopters) who are already used to wearing contact lenses. Ortho-k lenses can likewise be used by some people who currently wear bifocal glasses or progressive lenses. 

Those people who are unable to wear lenses normally are unlikely to be good candidates for ortho-k lenses, although it should be noted that the fact that they are worn at night means you are less likely to suffer from irritated eyes when wearing ortho-k lenses compared to other types of lenses.

Overnight vision correction lenses can, likewise, be suitable for the correction of myopia in children. Not only do ortho-k lenses slow the progression of myopia, the fact that these lenses are worn at night might prevent injuries in active and athletic children. 

How Are Ortho-K Lenses Worn?

Once you have been approved for orthokeratology lenses, these lenses will be especially designed for you.

Ortho-k lenses are worn exclusively at night. During the initial treatment phase, which lasts between one and four weeks, patients will go through an intensive period of wearing their overnight vision correction lenses every night, and while their eyes are adjusting, they will still require normal lenses during the day. 


Once this phase comes to an end, ortho-k lens users will be able to see well during the daytime without any vision correction. 


Some users have to wear their ortho-k lenses every night to achieve clear vision, while others can maintain their vision correction by wearing their ortho-k lenses every second night or even less frequently, in consultation with their eye care professionals. 

Are Ortho-K Lenses Safe?

Wearing lenses only at night sounds wonderful, but are ortho-k lenses safe?

It is important to note that the use all types of contact lenses is associated with an increased risk of eye infections, including frightening acanthamoeba infections that can lead to blindness. Taking lens care seriously is, therefore, crucial for anyone who uses them. 

One study demonstrated that the bacterial population seen in ortho-k lens wearers differed from that of soft contact lens users. Currently, over 100 case reports in which overnight vision correction lens wearers developed infectious keratitis are described in the medical literature. As not enough data is available to adequately asses the safety of ortho-k lenses, however, it is clear that further study is still required

This does not mean that individual patients should not choose ortho-k lenses for vision correction, as they have some clear benefits ordinary lenses do not offer. The pros and cons of overnight vision correction lenses need to be weighed in consultation with your eye care professional. 

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