Orthokeratology (OK), AKA Corneal Reshaping (CR)
Non-Surgical Vision Correction
Aaron Lee Nina Hernandez
FOX TV Tampa Bay, FL
Orthokeratology (OK), is a non-invasive, non-surgical procedure that is safe, effective, completely reversible and indefinitely "tunable," as vision changes. A specially designed hyper-oxygen permeable contact lens is used to gently reshape the front surface of the eye (the cornea) to correct myopia (nearsightedness) and mild astigmatism. OK has been called "braces for the eyes." Compared to LASIK surgery, there is no cutting of the corneal cap, no severing of the corneal nerves that are critically needed to maintain normal corneal physiology, and no lasing away of corneal tissue that thins and weakens the corneal structure.
The concept of OK has been around for many years and has evolved into an exact science. Recent technological advances in lens designs, materials and manufacturing have immensely improved the effectiveness and hence the popularity of the procedure. The procedure now allows the patient to wear the lenses overnight only, and remove them in the morning. This may correct their vision for up to several days without needing contact lenses or glasses at all! Initially, it can take as little as one to three days to correct a patient's vision and the ongoing wearing maintenance schedule may be as little as every other night.
Are You a Candidate?
There are limitations to OK, so not everyone can benefit from the procedure. Good candidates are those who have a nearsighted spectacle prescription of up to -4.00 diopters with up to -1.50 diopters of astigmatism. There are many documented cases that have been successful with much higher amounts of nearsightedness. Once we perform a full comprehensive exam, we can let you know if you are a candidate.
Myopic Progression Control [pdf] - adopted from a paper by Richard L. Anderson, O.D.
One of the most
exciting areas of research in Orthokeratology (Ortho-K), AKA, Corneal Reshaping
(CR), has to do with the control of myopic progression.
At the present time it appears very likely that CR can essentially stop the progression of myopia in the young, emerging myope. Finally we may have something that actually works. The jury is still out but the research continues and each new study is pointing in the same direction: The use of CR lens molding on the young myope is the best alternative for preventing the progression of myopia.
It's better than Rigid Gas Permeable lenses (RGPs), it's better than bifocals, it's better than progressive lenses, atropinizing drugs, vision therapy (VT) and it's better than under-correcting the myopia.
It is my belief that nearly every emerging myope should be given the opportunity to have CR. It allows the stabilization at low levels of myopia and the wearing time of the molds can often be reduced. They don't have to progress over three years from -.75 to -1.75 before you step in with a better alternative. You don't have to watch the average of -.37D per year progression. Keep them at a low level and they will most likely never desire any other type of correction, including Lasik.
Why does OK control myopia?
It turns out that myopia development appears to be controlled by the focus of the peripheral retina. At the recent Orthokeratology Academy of America meeting, there was a fair amount of discussion, continued from last year, about myopia control based on research by Earl Smith, O.D. of the College of Optometry, Houston. His research is with monkeys but the results have been found in many different species. The eye has a process called emmetropization that continually tries to zero-out refractive errors that is mediated primarily by the peripheral retina to a much greater degree than the central retina. The eyeball grows longer (axially) during maturation, which causes the myopia, and stops growing when the peripheral retina comes into focus.
peripheral hyperopia existing separate and distinct from "regular" or central (foveal)
focus, or what Dr. Smith calls hyperopic peripheral defocus. If you have good
central acuity, you still might have a peripheral defocus. If your peripheral
retina is hyperopic, in effect that image is behind the peripheral retina, then
the signal within the retina is to keep growing, and the central retina moves
further out (grows) from zero error (plano) to myopic if measured centrally,
like we all do measure it. If your peripheral retina is not hyperopic, in
effect the peripheral image is on retina and the retinal signal is to stop or
slow growth. The key to control the growth is curvature or shape “shell”of the
visual field - move the peripheral retina where it needs to be; for progressive
myopes, curve it inward (with more plus) in the periphery.
There appears to be an age limit of about 8 to actually reverse the process in humans. Older than that is mostly to slow or stop it from getting worse. Standard spectacle lenses with their "corrected curves" move the peripheral image in the direction that encourages myopic progression. CR corneas due to their peripheral reshaping, move the image in the direction that discourages axial growth. CR leaves the peripheral retina myopic outside the central 10 degrees or so. Instruments are being designed to allow peripheral refractions - in effect auto refractors that can measure off-axis rays. Such instruments have the promise of allowing us to accurately predict individual myopic risk.
The whole story won't be in for a long time. If you have absorbed what I have said above, you might say, "Just under-correct the kids: they'll have relatively less peripheral retinal hyperopia.” The problem is that the only two real studies that looked at this were stopped when it became evident that undercorrecting myopes made them worse compared to controls that were fully corrected.
The following studies have been done
with humans and OK.
LORIC (Long Term Ortho-K Research In Children) Pauline Cho showed that axial length increase was 50% in Ortho-K patients compared to the control group in glasses. Although Ortho-K slowed myopia, the effect couldn't be predicted for individuals.
Current Eye Research, 30:71–80, 2005
Copyright © Taylor & Francis Inc. ISSN: 0271-3863 print / 1460-2202 online http://www.exceleyecare.com/pages/5/The%20Longitudinal%20Orthokeratology%20Research%20in%20Children%20(LORIC)%20in%20Hong%20Kong.pdf
(Contact Lens And Myopia Progression) Jeff Walline studied 59 RGP eyes versus 57
soft lens eyes. There was no difference in axial length growth. RGPs flattened
the cornea .5D, while soft lenses steepened it .5D. RGPs slowed progression but
only a small amount.
Walline JJ, Jones LA, Mutti DO, and Zanik K: A Randomized Trial of the Effect of Rigid Contact Lenses on Myopia Progression. Arch Ophthalmol 122: 1760-1766, 2004
COMET (Correction of Myopia Evaluation Trial) Progressive Addition Lenses slowed myopic progression by .13D over five years, an effect considered negligible.
Gwiazda J, Hyman L, Hussein M, Everett D, Norton TT, Kurtz D, Leske MC, Manny R, Marsh-Tootle W, Scheiman M, and the COMET Group: A randomized clinical trial of progressive addition lenses versus single vision lenses on the progression of myopia in children. IOVS 44: 1492-1500, 2003.
(Corneal Reshaping and Yearly Observation of Nearsightedness) An update to the
Jeff Walline. CR slows axial growth over the study length of two years. Not yet published. Walline, Jeffrey J., Slowing Myopia Progression with Lenses, Contact Lens Spectrum, June 2007 2
(Children's Overnight Orthokeratology Investigation) essentially
proved that CR works overnight for children in the
8-11 year old group.
Invest Ophthalmol Vis Sci 2003;44: http://www.dreamlens.at/The_Childrens_Overnight.pdf
SMART (Stabilization of Myopia
through Accelerated Reshaping Technologies) A five year study where after each
year of wear the patient is allowed to normalize without wearing their molding
lenses after which they start wearing their lenses again. Preliminary results
show stability after one year.
The EyeVis Eye and Vision Research Institute.
CANDY (Controlling Astigmatism and Nearsightedness in Developing Youth) showed myopic progression of -.37D per year in normally corrected myopes and -.03D per year in CR patients. Patients were allowed to normalize at various times during their CR wear. The study graph below summarizes the data.
David Bartels, Peter Wilcox
The last two studies (SMART and CANDY) are attempting to answer the question of whether the stabilization is just a temporary phenomena that would disappear on cessation of lens wear. It appears that the CR effect is such that patients regress back to their starting point of CR wear, not partially regress or even progress to where they might have been if not wearing CR lenses.
The studies are not definitive. It will be a long time before such data is recognized as clinical fact. But, the overwhelming evidence at this time is that CR is a very good alternative for young myopes and the only real effective procedure we have of suspending the progress of myopia.
1. Goss DA, Grosvenor T. Rates of childhood myopia progression with bifocals as a function of near point phoria: consistency of three studies. Optom Vis Sci. 1990. 67: 637-40.
2. Fulk GW, Cyert LA, Parker DE. A randomized trial of the effect of single-vision vs. bifocal lenses on myopia progression in children with esophoria. Optom Vis Sci 2000, 77: 395-401.
3. Saw SM, Zhang MZ, Hong RZ, Fu ZF, Pang MH, Tan DT. Near-work activity, nightlights in the Singapore-China study. Arch Ophthalmol. 2002; 120:620-627.
4. Mutti DO, Mitchell GL, Moeschberger ML, Jones LA, Zadnik K. Parental myopia, near work, school achievement, and children’s refractive error. Invest Ophthalmol Vis Sci. 2002; 43:3633-3640.
5. Braun CI, Freidlin V, Sperduto RD, Milton RC, Strahlman ER. The progression of myopia in school age children: data from the Columbia Medical Plan. Ophthalmic Epidemiol. 1996; 3:13-21.
6. Hyman L, Gwiazda J, Hussein M, Norton TT, WangY, Marsh-Tootle W, Everett MA. Relationship of age, sex, and ethnicity with myopia progression and axial elongation in the Correction of Myopia Evaluation Trial. Arch Ophthalmol. 2005; 123:977-987.
7. Lee JJ, Fang PC, Yang IH, et al. Prevention of myopia progression with 0.05% atropine solution. J Ocul Pharmacol Ther 2006 Feb; 22(1):41-6.
8. Leung JT, Brown B, Progression of myopia in Hong Kong Chinese schoolchildren is slowed by wearing progressive lenses. Optom Vis Sci. 1999, 76:346-54.
9. Walline JJ, Jones LA, Mutti DO, Zadnik K. A Randomized trial of the effects of rigid contact lenses on myopia progression. Arch Ophthalmol 2004 Dec; 122(12):1760-6.
10. Katz J, Schein OD, Levy B, et al. A randomized trial of rigid gas permeable contact lenses to reduce progression of children’s myopia. Am J Ophthalmol 2003 Jul;136(1):82-90.
11. Smith EL. Mechanisms of myopia.
12. Jensen H. Myopia progression in young
school children and intraocular pressure.
Documenta Ophthalmologica 1992Sept;82(3) 249-255.
13. Park DJ, Congdon NG. Evidence for an “epidemic” of myopia. Ann Acad Med Singapore 2004 Jan; 33(1):21-6.
At SVC, we use state-of-the-art instruments and computers to take several measurements to calculate the precise design of CR lens you need. First, we perform a complete examination to determine your spectacle prescriptions, to assess the health of your eyes, and to determine if you are a good candidate for CR. Assuming you are a candidate, we proceed by using a Keratron Corneal Topographer (see picture at right), which measures tens of thousands of data points to map the topographic curvature of the cornea for a baseline starting point.
We also take a second set of corneal readings using an Auto-Keratometer which takes the curvature measurement using infrared light. This digital curvature data, as well as your spectacle prescription, are then input into a software program written by Dr. Berke which analyzes the data, and designs the optimum, one eye-one-lens contact lens. The information can then be directly uploaded to the lathe which produces your tailor-made lenses. If you have never worn contact lenses before, we will train you to insert, remove, and care for the lenses. We will start you on a wearing schedule based on your specific correction and then schedule you for regular follow-ups to assess your vision improvement with and without lenses. Once we have achieved our goal in correcting your vision, we will determine an appropriate wearing schedule which will maintain that desired vision. For example, depending on your initial prescription, you may only be required to wear your lenses through the night to maintain your vision throughout the day. Or, you may be able to maintain your corrected vision for days without wearing lenses.
Cost varies from $1250 to $2500 for both eyes depending on the case degree and complexity, number of follow-ups and the number of lenses required. We will inform you of exactly what your individual cost will be after your comprehensive exam.
Schedule an Appointment
If you are interested in this procedure and would like a free consultation with Dr. Berke, please call our office at 714-979-2021.