The rate of nearsightedness in the US has increased by over 66% in the past 30 years says a study published in the December 2009 issue of Archives of Ophthalmology
A 66% increase in myopia is a huge change over a 30 year period. The new study tried to simulate the testing methods of the original 1972 study on nearsightedness in the US population. The 1971-1972 National Health and Nutrition Examination Survey found that 25% of the US population between the ages of 12 and 54 were nearsighted vs the 1994-2004 National Health and Nutrition Examination Survey’s finding of 41.6%. Increased nearsightedness was noted regardless of age, sex, race or education.
The authors concluded that it would be beneficial to identify behavioral risk factors that cause increased myopia. If risk factors for increasing myopia are identified we may be able to slow the progression.
The big question is “what caused this increased nearsightedness in the US population”? As eye doctors we are often asked what causes nearsightedness and the usual answer is that that we believe nearsightedness is a combination of genetics and environmental influences. In the last 30 years our society has become much more near centric. People spend hours glued to their computer monitors at work and home. Kids spend more time at near now then ever before with computer games, hand held games etc.
Numerous recent studies have shown that orthokeratology contact lenses can greatly slow the progression of nearsightedness
Finding ways to slow or halt the progression of myopia has been a longstanding subject of study in eyecare. The process of using special contact lenses to reshape the front part of a patient’s eye to prevent the progression of nearsightedness and to allow the patient to see without glasses is called orthokeratology. There are a number of different names for orthokeratology, orthoK, corneal molding, corneal reshaping and corneal refractive therapy are some of the most common names.
Almost a year ago the study, Controlling Astigmatism & Nearsightedness in Developing Youth (CANDY) showed that orthokeratology contact lenses reduced the progression of nearsightedness in kids between 9 and 16. The authors of the CANDY study found that the amount myopia in children that did not wear the overnight Corneal Refractive Therapy lenses increased at a rate of .37D per year while those children wearing the lenses progressed at only .03 diopters per year.
Another study, Corneal Reshaping and Myopia Progression published in the British Journal of Ophthalmology, conducted at the Ohio State University College of Optometry found that the eyes of the children wearing overnight orthokeratology lenses increased in length at a markedly slower rate than the studies’ non ortho-K lens wearers.
Lastly, the study Stabilization of Myopia by Accelerated Reshaping Technique (SMART) is in the first of its five years and this past summer released preliminary results showing that again, orthokeratology lenses appear to markedly slowing the progession of nearsightedness in children.
While the rate of nearsightedness in the US population has increased significantly in the last 30 years it is comforting to know that there are safe and effective methods of slowing the progression of myopia. Download a PDF of the study Increased Prevalence of Myopia in the United States Between 1971-1972 and 1999-2004
Image courtesy of Flickr member Foxtongue.