Ortho-k (short for orthokeratology) is a means to gently reshape the front surface
(cornea) of the eye to give clear comfortable vision.
Ortho-k is also known as “CRT”, “Overnight Lenses”, “Dream Lenses”, “Corneal
Reshaping”, or “Vision Shaping”.
It is a non-surgical procedure using customized eye retainers at night that are removed
in the morning to give clear corrected vision all day without the use of contacts or
Patients have to wear the retainers each night, and because the procedure is
temporary, it is safer for children.
When a patient removes the retainers, the eye slowly returns to its former shape and
vision, usually taking several days to return to pre-ﬁtting parameters.
Ortho-k is to eye retainers as Orthodontics is to teeth retainer
Recall that most orthodontic patients wear the plastic teeth retainers after the dentists
remove the braces. The retainers keep the teeth straight, but if the patients stop
wearing them or wear them less, the teeth will shift.
3. Why think about ortho-k?
Myopia is fast becoming an epidemic. In the U.S., 42% of people ages 12-54 are
myopic. There are methods to slow or prevent the progression of myopia, but they work
best when the patient is younger.
Ortho-k has been shown to slow myopic progression the most out of all the methods in
controlled clinical trials. The trials have reported slowing myopia 55 to 100%. Other
case studies show high rates of prevention.
4. Who should consider ortho-k?
Best patients are approximately 10 years old, due to maturity and responsibility and
hygeine,who have shown progression in myopia within the past 2 years.
If both parents have myopia, risk for progression is greater.
Candidates usually ﬁnd glasses a nuisance as well. With glasses, there are constant
RX and thus lens changes, expenses with sports goggles and swim goggles for team
sports or P.E. classes, breakage or damage from Play, Recess or P.E., and fogging in
the rain or cold!
The idea of wearing no correction during the day also allows for freedom during Play,
Recess, and Sports.
5. What do ortho-k retainers look and feel like?
They look and feel like large Rigid Gas Permeable (RGP) lenses, approximately the
size of the colored part of the eye (iris).
6. Are there side effects?
Bad- As with contact lens patients, there is potential for infection.
There was an increase in infection with ortho-k retainers 15 years ago in Asia, at a time
when ﬁtting of the retainers were unregulated. Most infections were due to poor
compliance or poor training by practitioners in lens care.
Good- There are no lenses of any sort worn during the day when vision is clear!