EyeWitness

Spring 2017

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CLSA EyeWitness Spring 2017 23 tion: are there potential situations where we could be fitting contact lens- es in pediatric populations? I. Kids and Myopia Progression There is a growing body of literature that supports the clinical decision to utilize contact lenses in slowing the progression of myopia. However, it is important to keep in mind there is no current FDA ap- proval for this specific indication, either using contact lenses or any other type of treatment regimen. Multiple studies con- clude that when compared to a control group that is being corrected for their myopia rather than being treated for it, treatment groups exhibit a lower amount of refractive change over given time pe- riods (Table 2). Most these studies have surfaced in the last decade and are timely as the prevalence of myopia is reportedly on the rise around the world. Attempts to slow the progression of myopia have been clinically tested with atropine, re- duction of near work activity, bifocal and progressive addition spectacle lenses, orthokeratology, multifocal soft contact lenses, increased time outdoors, and even dietary changes. Although studies show that atropine therapy can nearly halt the progression of myopia in its 1% formula- tion, the negative side effects on children are not worth the refractive advantages, in this author's opinion. Contact lenses are an alternative to maintain the refractive error to a minimum while avoiding unwanted, potentially dangerous outcomes on a child's health. The mechanism of ex- actly how any of the above-mentioned treatment modalities function to alter the progression of myopia is not fully understood. Work carried out on ani- mal models points to inhibitory signals to axial elongation in the presence of peripheral myopic defocus 7 , a phenom- enon that can be accomplished with optics found in specific types of contact lenses. In other words, contact lens re- lated treatment of myopia progression should serve to increase the power of the eye in such a way to induce myopic blur beyond the fovea. Orthokeratolo- gy, or corneal reshaping lenses, and soft multifocal lenses serve as viable sourc- es of myopia treatment by allowing for mid-peripheral optics at the corneal plane to induce peripheral myopic de- focus at the retinal plane. a. Overnight Orthokeratology The use of gas permeable contact lens- es to temporarily alter the structure of the corneal surface is a widely accepted yet minimally practiced form of myo- pia correction and control. Anecdotal reports began to surface around the mid 1900's that PMMA lenses were ca- pable of controlling the progression of myopia, but it was not until 2005 when the first large scale study gave credibility to the claim that orthokeratology could reduce myopia progression. Its appeal to patients comes in the nighttime appli- cation of a contact lens which may allow wearers to enjoy being lens free wear during waking hours. For practitioners who have yet to carry out a successful orthokeratology fit, they may be apprehensive to suggest its beneficial impact to parents of my- opic children. Orthokeratology today includes reverse geometry lens designs in stable, high Dk lens materials. Over- night wear removes the discomfort typ- ically experienced with a corneal gas permeable lens modality. Contact lens professionals are required to be trained and certified by the corresponding laboratory before using orthokeratol- ogy in practice. Regardless of the de- sign, whether it consists of 3, 4, or more curves, they each generally consist of a specific width containing the base curve, a reverse curve, an alignment curve, and a peripheral zone that creates an appro- priate amount of edge lift off the corneal surface. Fitting of each design will vary slightly and the certification process will guide practitioners through the neces- sary steps to obtain proficiency in a spe- cific design. The survey mentioned earlier car- ried out by Efron et. al. over the 2005- 2009 time period revealed that out of all fits in the pediatric population un- der the age of 18 years old, orthoker- atology fitting accounted for 28% of the contact lenses prescribed. If this particular survey was repeated today, this percentage would likely be much higher as the interest in orthokeratolo- gy has grown. Ideal pediatric patients include those who present with myo- pia that is outside their age-accepted norms; those who show a clinically significant increase in cycloplegic-re- fractive error from one eye exam to the next; or those who although present with an age-expected amount of myo- pia, have one or more parents who is/ are highly myopic. All treatment options should be Authors Cho et al Walline et al Santodomingo- Rubido et al Cho et al Walline et al Aller et al Year of Publication 2005 2009 2009 2012 2013 2016 Study LORIC CRAYON MCOS ROMIO Multifocal contact lens myopia control CONTROL Type of CLs Worn by Treatment Group Orthokeratology Soft Multifocal Table 2: Studies that have shown the ability of contact lens use to decrease the progression of myopia in children.

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