Prevalence of myopia in the United States has increased to about 40 percent over the last 30 years.1 In East Asia, prevalence is about 75 percent and in some countries as high as 90 percent.2,3 Eyecare practitioners are diagnosing myopia at younger ages than we have seen in the past.4,5 Incidence of high myopia (>5.00 D) is increasing and carries with it risk for vision-threatening problems such as myopic macular degeneration, retinal detachment, glaucoma, and cataracts.6,7
Why are we seeing higher incidence of myopia, higher degrees of myopia, and earlier age of diagnosis? Research into the answers to these questions has come up with a variety of influences, but because the changes have been observed over such a short time (25 to 30 years) genetics cannot be the only factor.
Contributing risk factors identified for myopia development and myopia progression include:
• Family history8
• Time spent outdoors9,10
• Time spent on near work11,12
• Age of onset13
• Refractive status at specific age13
• Binocular vision status16
Table 1 shows these risk factors and details of their implications.
Efforts to control the progression of myopia have been studied in the past. But recent awareness of the seriousness of myopia and the number of patients affected has spawned a volume of studies on the various methods we have to slow myopic progression that are detailed below. They include environmental, optical (multifocal contact lenses, orthokeratology [ortho-k] contact lenses), and pharmaceutical.
Before prescribing myopia control techniques for your patients, keep in mind two important points. First, although the published data shows variable amount of control for each method, no single method is best for all patients. It is a custom and ongoing process that requires careful follow-up. Second, none of these methods currently have FDA approval for the indication of myopia control. As such, when prescribing these methods of myopia control, you are prescribing them for an off-label indication.
The accepted theory of optical control of myopia progression is based on creating myopic defocus on the retina peripheral to the macula.17,18 This is best accomplished using multifocal contact lenses or ortho-k.