Russell Lowe, Laura Downie. (2011) Corneal Reshaping Inhibits Myopia Progression (CRIMP)
The CRIMP study, a retrospective study of 32 orthok patients and 32 controls wearing spectacles. Although the presentation states that the groups were well matched, it is not possible to determine that given the data. The OK group averaged a year older, averaging 12.9 years. This would appear to be a poor design as the older patients would more likely already be slowing down their progression. 16% of eyes were washed out (allowed to regress without lens wear). It is stated that the controls progressed .29 diopters/yr and the OK group progressed .04 diopters (an 86% slowing.).
T. Kakita, T. Hiraoka, T. Oshika.(2011) Influence of Overnight Orthokeratology on Axial Length Elongation in Childhood Myopia. (ABSTRACT) Investigative Ophthalmology & Visual Science January 2011 (Published online before print) doi: 10.1167/iovs.10-5485
A prospective study of 210 eyes over two years with spectacle wearing students as controls matched for age, refractive error, gender, visual acuity and axial length. Over the two year study, the Ortho-K group’s axial length grew by .39mm and the control group by .61, a 36% reduction in myopic progression as measured by axial length.
Pauline Cho. (2011) Controlling the Progression of Myopia Using Contact Lenses. (ROMIO) Menicon
MyopiaPrevention.org comment: Not a journal article, but the only reference I can find so far for the ROMIO trial results. (You can see the trial parameters in the Clinical Trials section of this site.) After 6 months of a two year study, the ROMIO students wearing Ortho-K lenses had an axial length growth of .15mm vs .24 mm in the control group wearing spectacles, a reduction of 37%.
Peter E. Wilcox, David P. Bartels.(2010) Orthokeratology for Controlling Myopia: Clinical Experiences. Contact Lens Spectrum May 2010 39-42
Case report study for five patients showing a progression rate of .03 diopters per year for children fit with ortho-k lenses.
H.A. Swarbrick, A. Alharbi, K. Watt, E. Lum..(2010) Overnight Orthokeratology Lens Wear Slows Axial Eye Growth in Myopic Children.
Fourteen myopic children were fitted with ortho-k lenses in one eye and and daily wear lenses in the other eye. Lenses were worn for six months followed by a two week period of no lens wear and then lens-eye combinations were reversed and the lenses worn for six more months. For each eye when wearing the ortho-k lenses there were no significant change in axial lengths. Thus ortho-k is shown to stop myopia over a short term.
Walline JJ, Jones LA, Sinnott LT. (2009) Corneal reshaping and myopia progression. (ABSTRACT) Br J Ophthalmol. 93(9): 1181-5
This is the report of the CRAYON study (Corneal Reshaping And Yearly Observation of Nearsightedness). Ortho-K lenses slowed axial length and vitreous chamber depth (both indicators of slowing of myopia progression) compared to soft contact lens wear for 28 subjects over 2 years. Eye growth was slowed by a reported 55%, the vitreous chamber depth somewhat less percentage-wise.
Peripheral Refraction in Orthokeratology Patients. Optometry and Vision Science September 2006 – Volume 83 – Issue 9 – pp 641-648
Orthokeratology corrects the central 20 degrees of vision but very little beyond 60 degrees (30 degrees either side). The article concludes that if relative peripheral myopia limits myopic progression, then orthokeratology is an excellent option
Cho P, Cheung SW, Edwards M. (2005) The longitudinal orthokeratology research in children (LORIC) in Hong Kong: a pilot study on refractive changes and myopic control. (ABSTRACT) Curr Eye Res. 30(1): 71-80
Thirty five students fitted with ortho-k lenses for two years showed that axial length (a measure of myopic progression) was reduced by half in the ortho-k group as compared to the control group although the variations were very high.