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The Contact Lens Institute of San Antonio


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Myopia Control 

Melanie Frogozo OD


eprint before published in Contact Lens Spectrum 2017

Myopia is the most common eye disorder in the world. It is estimated that 4.8 billion people (49.8% of the world’s population) will be myopic by 2050 (1). Developed Asian countries are particularly affected. For example, in Singapore and Taiwan up to 84% of school aged children are myopic (2). In contrast, but still of concern, about 50% of adults in the United States and Europe are myopic. High myopia is a leading cause of blindness and is associated with comorbidities such as retinal detachment, macular choroidal degeneration, premature cataract, and glaucoma (3). Pediatric onset is most troublesome since this leaves more time for progression to higher myopia. Preventing children from developing high myopia and its associated visual impairments is, therefore, crucial.


Either preventing the onset of, or limiting the progression of myopia is considered myopia control. Effective approaches for limiting the progression include antimuscarinic agents such as atropine, orthokeratology, and soft dual focus contact lenses (4). Nevertheless, all myopia control strategies are off-label. Myopia control with contact lenses is accomplished by providing a myopic blur cue to the retina, which is assumed to act as a retinal cue to slow myopic eye growth (4). This article concentrates on contact lens interventions for pediatric myopia control.


Orthokeratology

Orthokeratology uses gas permeable lenses worn overnight to temporarily reshape the cornea to correct for refractive error during waking hours (Figure 1). Myopic orthokeratology shifts the cornea from its normal prolate aspheric shape towards an oblate asphere (5) (Figure 2). When reshaped the central apex is flatter than the midperipheral cornea creating the needed distance correction and also the peripheral defocus cue. On average, orthokeratology slows myopic progression by about 50% (4).


Soft Dual Focus Lenses

Soft dual focus contact lenses come in both center distance and center near designs. Most commercially available molded soft dual focus lenses are center near designs, however, there are more myopia control studies using center distance dual focus lenses. On average, soft dual focus contact lenses slow myopic progression by about 50% (4).


Other Contact Lens Options
Gas permeable lenses effectively correct high amounts of myopia and astigmatism. Dual Focus gas permeable lenses are, therefore, better suited for myopia control in children with high amounts of refractive error who are difficult to correct with orthokeratology or soft dual focus lenses (6). Many corneal and scleral gas permeable lenses are commercially available in dual focus designs. Hybrid lenses also are available with dual focus parameters.
Summary


Myopia is a disease whose prevalence is increasing worldwide. High myopia is best prevented and myopia control offers a solution. Early intervention is best and contact lens based interventions aim to create a peripheral defocus retinal cue that slows myopic progression. Management may involve orthokeratology or dual focus contact lenses including soft or gas permeable varieties as the situation warrants.



References
1. Holden et al. Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmology 2016; 123(5)1036-1042.
2. Wu PC, Huang HM. Epidemiology of Myopia. Aisa Pac J Ophthalmol 2016; 386-393.
3. Cho BJ, Shin JY, Yu HG. Complications of Pathologic Myopia. Eye & Contact 2016;42:9-
4. Walline JJ. Myopia Control. Eye & Contact Lens. 2016;42:3-8.
5. Rinehart J. “Orthokeratology” in Manual of Contact Lens Prescribing and Fitting Third
Edition, Hom MM and Bruce AS. Elsevier St Louis, MO 2006: 637-686.
6. Liu M. “MYOPIA CONTROL CLINIC AT UC BERKELEY EYE CENTER.” Vision By Design 2017
Annual Meeting. The American Academy of Orhtokeratology and Myopia Control.



Figure 1. Orthokeratology gas permeable lens on eye. On average, orthokeratology slows myopic progression by 43%













 
Figure 2. Orthokeratology lenses flatten the central apex and steepen the midperipheral cornea thus creating the needed distance correction and also the peripheral retinal defocus cue for myopia control.