The Business of Contact Lenses
Myopia Is a Disease, People!
BY CLARKE D. NEWMAN, OD, FAAO
The future of successful contact lens practice will have to include methods for controlling the progression of myopia. Why do I say this? Well, according to research presented at this year’s Global Specialty Lens Symposium and the British Contact Lens Association’s meeting, the myopia epidemic is one of the great epidemics in the world today.
Further, the recent evidence base proffers an explanation for myopia progression and support for the control of that progression with contact lenses and medications. Both of these treatment modalities, as well as the diagnostic process to diagnose malignant myopia, are well within an eyecare practitioner’s grasp.
Statistics Show Increases
Let’s look at some numbers. Myopia is increasing at an alarming rate; the incidence of myopia has increased to 42% in the United States and to 35% in Europe (Morgan et al, 2012). In Asia, the increase in myopia is especially alarming. In much of Asia, with South Korea leading the way, the incidence is around 85% (Morgan et al, 2012).
Also, the magnitude of myopia is increasing, and that increase is not benign. There is an increase in myopic retinal degeneration that has real-world morbidity that results in vision loss. Drobe (2013) shows that the odds ratio of myopic macular degeneration increases 10-fold when the level of myopia is greater than 4.00D. This myopic maculopathy is not as rare as you might think. According to Ian Flitcroft (2012), myopic maculopathy is the fourth leading cause of blindness—ahead of diabetic retinopathy in the United Kingdom. Further, he reports a much higher rate of retinal detachment in significantly myopic patients.
Of the top causes of vision loss, myopic maculopathy is the only one without a therapeutic standard care. However, there are a few therapeutic strategies for myopia progression.
Managing Myopia Progression
What does the evidence base suggest about the etiology of myopia progression? Smith (2011) proffers that there is a peripheral defocus that occurs with foveal focus in these patients. So, correcting the peripheral focus could possibly make a dent. However, according to Flitcroft (2012), a 1.00D reduction in myopia above 6.00D translates to a one-third reduction in myopic maculopathy.
There is an imperative for the reduction of myopia progression and magnitude. First, we must diagnose the condition. How can you predict progression? According to Gwiazda et al (2004), the answer lies in having myopic parents, having a low accommodative convergence to accommodation (AC/A) ratio, and having eso deviations. Also, Rose et al (2008) report that kids who spend 90 minutes outdoors each day had significantly less myopia compared to those who spent less time or no time outdoors. So, we have to ask the question, “How much time does your kid spend outdoors?”
Further, treatment options include contact lens correction and medical therapy. We have seen much in the literature lately discussing the use of orthokeratology and multifocal—particularly center-distance aspherical—designs as a treatment for myopia progression; in light of Smith’s work, this tends to make sense. By creating optics that correct peripheral, as well as central, focus, the research shows that these treatment modalities result in a reduction of axial length.
Finally, there is a significant body of evidence suggesting that M1 and M4 cholinergic antagonists, such as atropine and pirenzepine, are the best therapies for myopia progression.
We need to incorporate these treatments into our practices and promote them to families. CLS
For references, please visit www.clspectrum.com/references and click on document #237.
Dr. Newman has been in private practice in Dallas since 1986 specializing in vision rehabilitation through contact lenses as well as corneal disease management, optometric medicine, and refractive surgery. He is a Diplomate in the AAO and a consultant to B+L, AMO, and Alden Optical. Contact him at email@example.com.