Orthokeratology (ortho-k or orthok) is the process of wearing a custom designed molding contact lens only while sleeping. The lens is removed each morning and the result is good vision all day with no contacts or glasses. As a side benefit the procedure also slows down the progression of myopia in most studies.

Russell Lowe, Laura Downie. (2011) Corneal Reshaping Inhibits Myopia Progression (CRIMP)(Slide Presentation) Lecture at SRC 2011 May 2011

MyopiaPrevention.org comment: This is the only online information I can find currently (June 2011) on the CRIMP study. It apparently is a slide presentation given at the Southern Regional Congress and Trade Expo in Melbourne, Australia in May 2011.

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.) No axial length measurements were taken. It is difficult to evaluate the results from just the slides, but that can not be a criticism as they were not intended to stand alone. We will just have to wait for a published document.

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%.

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

MyopiaPrevention.org comment: Formerly a poster presentation listed here: Presentation ARVO 2010 Program:2195 Poster:A294 (ABSTRACT) . 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.

Peter E. Wilcox, David P. Bartels.(2010) Orthokeratology for Controlling Myopia: Clinical Experiences. (FULL TEXT) Contact Lens Spectrum May 2010 39-42

MyopiaPrevention.org comment: An anecdotal case report study for five patients showing a progression rate of .03 diopters per year for children fit with ortho-k lenses. They outline their CANDY plan (Controlling Astigmatism and Nearsightedness in Developing Youth.)

H.A. Swarbrick, A. Alharbi, K. Watt, E. Lum..(2010) Overnight Orthokeratology Lens Wear Slows Axial Eye Growth in Myopic Children. (ABSTRACT) Presentation ARVO 2010 Program:1721 Poster:A178

MyopiaPrevention.org comment: A poster presentation. 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.

E. Okada, K. Kimbara, K. Iyanaga, N. Tabei, T. Hidaka, M. Nagasaki, T. Yokoyama, H. Kamezawa, N. Mizuki.(2010) Longitudinal Analysis of Orthokeratology Outcome for Myopia Correction in Comparison With Other Lenses and Spectacles (ABSTRACT) Presentation ARVO 2010 Program:1528 Poster:D819

MyopiaPrevention.org comment: A poster presentation. Orthokeratology patients under 18 did not increase in refractive power over the five years of the study compared with progression rates of soft, hard and spectacle lenses, but the data presented in the abstract does not allow determination of subject parameters such as age or refractive state and the drop out rate is not clear.

Queirós A, González-Méijome JM, Jorge J, Villa-Collar C, Gutiérrez AR.(2010) Peripheral refraction in myopic patients after orthokeratology. (ABSTRACT) Optom Vis Sci. 2010 May;87(5):323-9.

MyopiaPrevention.org comment: Peripheral refractions were studied for 28 eyes that had ortho-k. Ortho-K created myopic reduction for the central retina and a myopic shift beyond 25 degrees. Between 30 and 35 degrees the amount of myopia induced almost exactly matches the amount of myopic reduction centrally. This proves that corneal peripheral steepening seen in topography after ortho-k is transferred optically to the retina.

Queirós, Antonio; González-Méijome, Jose Manuel; Villa-Collar, Cesar; Gutiérrez, Angel Ramon; Jorge, Jorge (2010) Local Steepening in Peripheral Corneal Curvature After Corneal Refractive Therapy and LASIK. (ABSTRACT) Optometry & Vision Science: Post Author Corrections, 8 April 2010 [cited 2010 Apr 15]

MyopiaPrevention.org comment: LASIK and Ortho-K have similar corneal shapes with ortho-k having an area of corneal steeping 1mm smaller and higher mid peripheral steeping than LASIK, perhaps creating a greater peripheral myopic focus, which may "have implications" for myopia control.

Queirós, António; González-Méijome, José Manuel; Jorge, Jorge; Villa-Collar, César; Gutiérrez, Angel R.(2010) Peripheral Refraction in Myopic Patients After Orthokeratology. (ABSTRACT) Optometry & Vision Science. Post Author Corrections, 1 April 2010 doi: 10.1097/OPX.0b013e3181d951f7 [cited 11 April 2010]

MyopiaPrevention.org comment: Changes in the peripheral refraction after orthokeratology were essentially unchanged at 25 degrees peripheral to centration but at 30 and 35 degrees, a myopic shift was highly correlated (1:1) with the amount of central (axial) treatment. It would appear that the circular treatment zones molded onto the cornea create a myopic focus shift starting at about 30 degrees.

Cary M. Herzberg (2010) An Update on Orthokeratology. Contact Lens Spectrum (FULL TEXT) March 2010

MyopiaPrevention.org comment: This is a summary of where orthokeratology technology stands today by the president of the Orthokeratology Academy of America.

Joseph Ruskiewicz.(2009) Ortho-K: An Answer for Myopia Control. (FULL TEXT) Review of Optometry Vol. No: 146:03 Issue: 3/15/2009

MyopiaPrevention.org comment: Quoting: "Myopia is a costly, life-long problem. But, orthokeratology can help control myopia and prevent further progression." This is not a review or research article, but rather a narrative about the advantages of ortho-k with a couple of case reports.

Jacinto Santodomingo-Rubido, César Villa-Collar, Bernard Gilmartin and Ramón Gutiérrez-Ortega. (2009) Myopia Control with Orthokeratology Contact Lenses in Spain (MCOS): Study Design and General Baseline Characteristics. (FULL TEXT) J Optom 2009;2:215-222

MyopiaPrevention.org comment: Baseline data for a prospective study comparing the axial length growth of myopic white European children and their spectacle wearing counterparts. The control group was well matched. It also will collect any adverse event data. Expected completion date: 2013.

S. Barry Eiden, Robert L. Davis, Edward S. Bennett, and Julie O. DeKinder. (2009) The SMART Study: Background, Rationale, and Baseline Results (FULL TEXT) Contact Lens Spectrum October 2009

MyopiaPrevention.org comment: This is the preliminary set-up report for the SMART (Stabilization of Myopia through Accelerated Reshaping Technologies) trial. First year results have not been published as of 4/1/2010. This study uses a "wash-out" period each year where the ortho-k molding lenses are removed until the cornea stabilizes, then wearing is resumed. Preliminary results show that myopia is reduced significantly in the ortho-k group but both the control and treatment group had an essentially equal changes in vitreous chamber depth (an increase) and axial length (no change).

Josh Lotoczky, Bruce Morgan.(2009) Myopia Control With the Euclid Emerald Contact Lens and Overnight Orthokeratology. (ABSTRACT) Optometry Volume 80, Issue 6, Pages 291-292 (June 2009) Poster 12

MyopiaPrevention.org comment: A case study report. Nine children aged 10-16 at the time of the start of the study had ortho-k lenses for 4 years at which time there was a three week wash-out period of no wear. The total progression averaged a .05 Diopter increase in myopia, essentially no change.

Walline JJ, Jones LA, Sinnott LT. (2009) Corneal reshaping and myopia progression. (ABSTRACT) Br J Ophthalmol. 93(9): 1181-5

MyopiaPrevention.org comment: 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.

Bob Kronemyer. (2007) Research encouraging for controlling myopia by reshaping the eye’s front surface. (FULL TEXT) Primary Care Optometry News 7/1/2007

MyopiaPrevention.org comment: This is an online news article from 2007 that is hesitant to claim myopia control by ortho-k until further studies are completed.

Watt KG, Swarbrick HA.(2007) Trends in microbial keratitis associated with orthokeratology. (ABSTRACT) Eye Contact Lens.2007 Nov;33(6 Pt 2):373-7; discussion 382.

MyopiaPrevention.org comment: Over half of the reported cases in the literature of infections related to orthokeratology occurred in the year 2001 and that year all cases were from East Asia during a time when the practice was generally unregulated. The higher incidence of microbes found in tap water confirm the need for proper instruction in lens care and handling.

Peripheral Refraction in Orthokeratology Patients. (FULL TEXT) Optometry and Vision Science September 2006 - Volume 83 - Issue 9 - pp 641-648

MyopiaPrevention.org comment: 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.

Swarbrick HA.(2006) Orthokeratology review and update. (FULL TEXT) Clin Exp Optom2006 May;89(3):124-43.

MyopiaPrevention.org comment: A review as of 2006 of the efficacy of ortho-k, mechanisms and safety. While studies have indicated benefits in slowing myopic progression, the author would "argue strongly for a more rigorously controlled, prospective, randomized and masked clinical study to confirm these promising findings."

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

MyopiaPrevention.org comment: 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. The control group was actually from a different study matched for age, gender and baseline refraction, not the best study design.

Walline JJ, Holden BA, Bullimore MA, Rah MJ, Asbell PA, Barr JT, Caroline PJ, Cavanagh HD, Despotidis N, Desmond F, Koffler BH, Reeder K, Swarbrick HA, Wohl LG. (2005) The current state of corneal reshaping. (ABSTRACT) Eye Contact Lens. 2005 Sep;31(5):209-14.

MyopiaPrevention.org comment: Among other comments, they state that "claims about the progress of myopia being controlled with corneal reshaping contact lenses should not be made until further studies are published in peer-reviewed literature."

Jeffrey J. Walline, Marjorie J. Rah, Lisa A. Jones. (2004) The Children's Overnight Orthokeratology Investigation (COOKI) Pilot Study (FULL TEXT) Optom Vis Sci. 2004 Jun;81(6):407-13

MyopiaPrevention.org comment: Twenty nine 8-11 year old children were enrolled in the study to wear over-night orthokeratology lenses. Twenty four completed the study over 6 months with good vision and no serious problems. Of the 5 that did not complete the study, only one dropped due to dissatisfaction with the process.

Reim TR, Lund M, Wu R (2003) Orthokeratology and adolescent myopia control. (ABSTRACT) ) Contact Lens Spectrum 2003; 18(3)

MyopiaPrevention.org comment: One of the first attempts to begin studying the relationship of ortho-k to myopia control. Although the effect was detectable, it was not considered proof enough to claim a reduction in rate of progression.