© Davis Eye Associates 2014
Made with Xara
While you may be unfamiliar with Ortho-K, it has been around for many
years with research proven results. Summarized below are some of the
many research studies on Orthokeratology.
For additional information, you may access the Orthokeratology
Academy of America, the Ortho-K Newtork, or Myopiaprevention.org.
COOKI (Children's Overnight Orthokeratology Investigation)
Innovations in contact lens materials and designs allow patients to wear contact lenses during
sleep to flatten the cornea and temporarily reduce myopic refractive error and improve unaided
visual acuity. The Children's Overnight Orthokeratology Investigation (COOKI) pilot study, a case
series, was conducted to describe the refractive error and visual changes, as well as the slit lamp
(microscope) observations associated with overnight Orthokeratology in children, over a period of
Conclusions: Overnight cornea-reshaping contact lenses are efficacious for young myopic
patients, and no children experienced a serious adverse event during the study.
C.A.N.D.Y. STUDY (Controlling Astigmatism and Nearsightedness in Developing
Exciting Study published Fall, 2008 in Contact Lens Spectrum.
This study's goal was to compare the change in myopia and astigmatism in patients aged 8 to 18
while wearing Orthokeratology versus no glasses or contact lenses. Protocol: patients used Ortho-
K lenses for various periods ( 7 months to 57 months ) then discontinued use of the lenses for
about a month until their corneas resumed their natural shape. Prescriptions were assessed and
the amount of change in nearsightedness was reviewed and compared to the control group.
Conclusions: "Ortho-K does both significantly reduce and even stop the rate of change of
nearsightedness and astigmatism in developing youth (ages 9-18)." Read the Complete CANDY
LORIC (The Longitudinal Ortho-K Research In Children)
This study looked at several factors. It was to determine whether Orthokeratology can effectively
reduce and control myopia in children. It also compared Orthokeratology treatment with single
vision spectacles. It monitored the growth of axial length and the vitreous chamber depth. It also
monitored corneal curvature and the relationships with changes of refractive errors.
The mean increase in axial length for the Orthokeratology group was 0.14 mm per year compared
with the mean increase in axial length for the spectacle lens wearers of 0.27 mm per year. In the
spectacle wearing group, the eye elongation is faster in those with higher baseline prescriptions.
Orthokeratology would benefit higher baseline prescriptions as eye elongation is slower in these
subjects. Higher myopia showed greater slowing of progression in the Orthokeratology group.
Conclusions: Study subjects found post Orthokeratology unaided vision acceptable in the daytime,
and slowed their vision change 50% compared to spectacle wearers.
Refraction, contrast sensitivity rebound after completion of orthokeratology.
May 1, 2009. Refractive Surgery/Ocular Surgery News, Europe/Asia-Pacific Edition. This study is
the first to show the effects of orthokeratology to be reversible after 1 year of treatment, Takahiro
Hiraoka, MD, PhD, said in an e-mail interview with Ocular Surgery News.
"The most important finding of our study is that the effect of orthokeratology is completely
reversible in light of optical quality of the eye and quality of vision, as well as refraction and visual
acuity," Dr. Hiraoka said.
Conclusions: Orthokeratology proved reversible in a study, with refraction and visual acuity
returning to baseline levels 1 week after the treatment was completed.
Corneal Reshaping and Myopia Progression
May 4, 2009. JJ Walline, LA Jones, LT Sinnott. Journal of Ophthalmology. Anecdotal evidence
indicates that corneal reshaping contact lenses may slow myopia progression in children. The
purpose of this investigation is to determine whether corneal reshaping contact lenses slow eye
growth. Forty subjects were fitted with corneal reshaping contact lenses. All subjects were 8 to 11
years and had between -0.75 D and -4.00 D myopia with <1.00 D astigmatism. Subjects were
age-matched to a soft contact lens wearer from another myopia control study. A-scan ultrasound
was performed at baseline and annually for two years.
Twenty-eight of 40 (70%) subjects wore corneal reshaping contact lenses for two years. The
refractive error and axial length were similar between the two groups at baseline. The corneal
reshaping group had an annual rate of change in axial lengths that was significantly less than the
soft contact lens wearers. Vitreous chamber depth experienced similar changes.
Conclusions: Results confirm previous reports of slowed eye growth following corneal reshaping
contact lens wear.
CLAMP (Contact Lens And Myopia Progression)
This study had several goals. To evaluate the effect of rigid lenses on myopia progression in
children. To determine the mechanism of effect if one exists. To examine the efficacy of rigid
contact lenses for the treatment of myopia in young children. To compare vision and comfort
issues between rigid and soft contact lens wearers.
Although corneal curvature changed, the axial growth was not significantly different between the
groups. The decreased refractive error progression is not accompanied by slowed axial growth.
The corneal curvature changes during corneal reshaping contact lens wear are reversible. The
treatment effect experienced in the CLAMP study may not be permanent. Most of the effect on
refractive error was limited to the first year of the trial. The study did not indicate that rigid gas
permeable lenses should be prescribed primarily for the intent of myopia control.
Conclusions: Rigid gas permeable lenses produce a slower rate of progression of myopia in
children than soft contact lenses.