What is Ortho-K?
Orthokeratology, or Ortho-K, is a non-surgical procedure to reduce or correct nearsightedness (myopia) in both adults and children using custom made contact lenses. Similar to using a dental retainer to realign teeth, these lenses are worn during sleeping hours. In the morning, they are removed to provide clear functional vision without glasses or contact lenses during the day.
These custom made contact lenses are worn overnight to gently shape the cornea so that it keeps its new shape throughout the next day. Once the new shape is well established, which may take several months, many patients can reduce how often the lenses are worn and still maintain clear functional vision.
The benefits of Orthokeratology will fade if lens wear is completely stopped. Orthokeratology is predictable, reversible and adjustable over time. It provides clear comfortable vision, free from the distractions people often experience with contact lenses or glasses such as: dryness, irritation from wind, dust, allergies, raindrops on glasses, etc.
To benefit from Orthokeratology, several visits to the clinic will be necessary.
First, a picture of the cornea is taken to map out its unique curves. This scan takes a few minutes and provides crucial details needed to design your custom lenses, it also tells us whether or not the patient is likely to benefit from the procedure.
The rigid gas permeable contact lenses are then ordered from the laboratory and ready to be fit. Instructions on lens insertion, removal and care for the lenses are provided at that visit.
After 1 or 2 nights of wear, we measure the improvement in vision and to check the corneal health at our clinic. Occasionally the trial lenses may be too flat or too curved and not give the expected outcome. These results tell us what changes need to be made to the lens design before repeating the fitting process.
If the trial succeeds as expected, we can proceed with the treatment. If it is unlikely that Ortho-K will work for you, a consultation with Dr. Kuang will help determine which other form of myopia control will be the most suitable.
Orthokeratology is currently the best prescription lens device to slow the progression of nearsightedness.
Who can benefit?
Children or young adults may benefit from myopia control if they fit one or more of the following criteria:
- Family history of nearsightedness (parents or siblings with a prescription of greater than -6 D)
- Nearsightedness started before the age of 10
- Nearsightedness is progressing at -1 D/year or more
Ortho-K started in the 1960’s when people noticed seeing clearly even after removing their contact lenses. More recently technological advances made precise digital corneal mapping, measurements and the fabrication of oxygen permeable polymers possible, allowing safe overnight wear of contact lenses.
According to the Canadian Association of Optometrists, myopia currently affects 30-40% of the Canadian population. In some Asian populations, the prevalence is as high as 70-90%2. By 2050, 50% of the world is projected to have myopia, 10% will have high myopia.1
Mild myopia usually poses no ocular health concerns but moderate (-3.25 D to -6.00 D) to high myopia (greater than -6.00 D) does. In progressive high myopia, the eyeball grows longer from front to back, causing the retinal tissue to thin. The elongation of the eyeball is associated with retinal thinning and tears, which may lead to retinal detachments.
Myopia is also correlated with myopic macular degeneration, glaucoma and the early formation of cataracts3. This is concerning since myopia is becoming more and more prevalent.
For some other options on slowing down the progression of nearsightedness, see the table18 below:
|Vision correction||Slowed myopia progression by…||Duration of study||Additional information|
|MyoVisionTM single vision lenses||0-30 %4||12 months||30% less progression seen with children aged 6-12 with parental history of myopia.|
|Multifocal soft contact lenses||29-50 %5-6||12-48 months|
|Orthokeratology||32-100 %7-14||12-60 months|
|Atropine eye drops (normally enlarges the pupil and prevents the eye from being able to focus)||30-77 %15-17||24-36 months||0.01% Atropine showed 64% effect without usual side effect of sensitivity to glare and need for constant reading glasses.|
- Holden BA, Fricke TR, Wilson DA, Jong M, et al. Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmology 2015;123(5):1036-42.
- Fredrick DR. Myopia. British Medical Journal 2002;324(7347):1195–1199.
- Heiting, Gary. Why Myopia Progression Is a Concern. February 2016.
- Sankaridurg P, Donovan L, Varnas S, et al. Spectacle lenses designed to reduce progression of myopia: 12 month results. Optom Vis Sci 2010;87:631-41.
- Walline JJ, Greiner KL, McVey ME, Jones-Jordan LA. Multifocal contact lens myopia control. Optom Vis Sci 2013;90:1207-14.
- Anstice NS, Phillips JR. Effect of Dual-Focus Soft Contact Lens Wear On Axial Myopia Progression in Children. Ophthalmol 2011;118:1152-61.
- Cho P, Cheung SW, Edwards M. The Longitudinal Orthokeratology Research in Children (LORIC) in Hong Kong: A pilot Study on Refractive Changes and Myopic Control. Current Eye Res 2005;30:71-80.
- Walline JJ, Jones LA, Sinnott LT. Corneal reshaping and myopia progression. Br J Ophthalmol 2009;93:1181-5.
- Swarbrick HA, Alharbi A, Watt K, Lum E. Overnight Orthokeratology Lens Wear Slows Axial Eye Growth in Myopia Children. Invest Ophthalmol Vis Sci 2010;51:1721
- Kakita T, Hiraoka T, Oshika T. Influence of overnight orthokeratology on axial elongation in childhood myopia. Invest Ophthalmol Vis Sci 2011;52:2170-4
- Charm J, Cho P. High myopia-martial reduction ortho-K: A 2-year randomized study. Optom Vis Sci 2013;90:503-9.
- Hiraoka T, Kakita T, Okamoto F, Takahashi H, Oshika T. Long-term effect of overnight orthokeratology in childhood hopia. Invest Ophtalmol Vis Sci 2012:311
- Santodomingo-Rubido J, Villa-Collar C, Gilmartin B, Gutierrez-Ortega R. Myopia control with orthokeratology contact lenses in Spain: refractive and biometric changes. Invest Ophthalmol Vis Sci 2012;53:5060-5.
- Sun Y, Xu F, Zhang T, et al. Orthokeratology to Control Myopia Progression: A Meta-Analysis. Al-Ghoul KJ, ed. PLoS ONE. 2015;10(4):e0124535. doi:10.1371/journal.pone.0124535.
- Chua WH, Balakrishnan V, Chan YH, et al. Atropine for the treatment of childhood myopia. Ophthalmology 2006;113:2285-91.
- Tong L, Huang XL, Koh ALT, Zhang X, Tan DTH, Chua W-H. Atropine for the Treatment of Childhood Myopia: Effect on Myopia Progression after Cessation of Atropine. Ophthalmology 2009; 116:572-9.
- Chia A, Chua W-H, Cheung Y-B, et al. Atropine for the Treatment of Childhood Myopia: Safety and Efficacy of 0.5%, 0.1%, and 0.01% Doses (Atropine for the Treatment of Myopia 2). Ophthalmology 2012;119:347-54.
- Gifford, Kate. Myopia Profile. N.p., 05 Feb. 2016. Web. 20 June 2016.