Pediatric and Teen CL Care
Orthokeratology Possibilities for Children
BY MELANIE FROGOZO, OD, FAAO
Orthokeratology (OK) is a nonsurgical procedure using GP contact lenses to temporarily reduce refractive error. There are also designs that correct for hyperopia as well as for regular astigmatism. Since a patient’s refractive error does not have to be stable, OK is a good choice for correction in children (Rhinehart, 2006). This article describes how OK may slow myopia progression and discusses how it benefits the pediatric population.
A regular cornea has a prolate shape in which it is steeper centrally and flattens toward the periphery. Myopic OK utilizes corneal GP lenses to flatten the central cornea to a more spherical shape. Or, in cases in which higher myopia is corrected, OK changes the cornea to a reverse oblate configuration.
Currently, large-diameter (>10mm) reverse geometry corneal GP lenses are used for OK. This design aids in lens centration and stability by having a steeper peripheral curve in comparison to the adjacent base curve. Figure 1 shows a typical fluorescein pattern of an OK lens in which there is touch at the central optic zone, pooling in the area of the steeper reverse curve, and alignment in the periphery.
Figure 1. A typical orthokeratology fluorescein pattern.
COURTESY OF BRIDGETTE YEOH, OD.
Generally, lenses are fitted flatter than K in the amount of myopic correction needed. For example, if a patient has 2.00D of myopia and his flat K is 43.00D, the base curve needed to correct for this amount of myopia is 41.00D.
Benefits of OK
Because GP lenses are available in high-Dk materials, most patients who undergo OK wear their lenses overnight. Therefore, one benefit of OK use for children is decreased dependence on corrective lenses during the day. This makes OK an especially good option for children who are active in sports and extracurricular activities. Additionally, OK is an alternative for patients who, due to dryness or allergies, are contact lens-intolerant during the day.
The most interesting benefit of OK for children is the possibility of slowing the progression of myopia. Parents who are myopic are usually concerned that their children will also reach the same degree of myopia. In addition, high myopia is associated with sight-threatening complications, including retinal disease, glaucoma, and cataracts.
There is now an increasing amount of evidence showing that OK slows the progression of myopia and thus reduces its associated complications (Walline, 2015). Myopic children who wear OK lenses have a decreased rate of axial length growth in comparison to children wearing single-vision spectacles (Charm and Cho, 2013; Cho and Cheung, 2012).
For children who either prefer not to or who cannot wear corrective lenses during the day, OK can reduce or eliminate the need for vision correction. While the patients may focus on the cosmetic benefits, the true power of OK is its ability to limit myopia progression in children. This makes OK particularly important for children at risk for developing high myopia. CLS
For references, please visit www.clspectrum.com/references and click on document #243.
Dr. Frogozo specializes in adult and pediatric specialty contact lenses. She is the director of the Contact Lens Institute of San Antonio and the owner of Alamo Eye Care in San Antonio, Texas. She also was a consultant to CooperVision. You can contact her at firstname.lastname@example.org.