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The Myopia Epidemic

Derek B. Hennig, OD

We’ve all heard the term myopia at some point in our lives… okay so maybe we haven’t. What is myopia? Myopia is the medical term for an eye that is larger than average (think of comparing the size of a golf ball to a tennis ball), thus creating a scenario where light is not focused properly on the retina. This, of course, leads to blurred vision in a pattern that is commonly known as “nearsightedness.” The biggest problem with myopia, however, is often not related to blurred vision. That can be corrected with glasses, contact lenses, or surgical procedures in most cases. The problem with myopia is that because the eye is larger than normal, the risk for developing several sight-threatening eye diseases is much higher than an eye of normal size. As technology advances each year, optometrists and ophthalmologists worldwide are seeing a drastic increase in the number of children developing myopia. Thinking long-term, this could have a major impact of the prevalence of many eye diseases as this population ages.

The Trend

In 2010, nearly two billion people had been diagnosed with myopia worldwide, or about 28% of the world’s population, according to a study completed by the Brien Holden Vision Institute. In North America, the current number shows that 30-35% of the population is myopic. It is predicted that myopia will affect around five billion people by 2050, or about 50% of the world’s population. Based on what we know about the eye health risks in myopia, that means around one billion people in 2050 will be at significant risk of vision impairment and blindness. That’s a BIG number!

The Cause

Many past and present studies have and continue to look into what is causing the dramatic rise in myopia that we have seen over the past three decades. Though the answer is not definitive, we know that the rate of change over those decades is too fast to be attributed to genetics alone. But genetics do play a role; a child with one myopic parent is three times more likely to develop myopia, and a child with two myopic parents is six times more likely to develop myopia. Other theories revolve around the amount of time spent in natural sunlight and on near tasks, such as reading, tablets, phones, etc. Children that spend more time outdoors are less likely to develop myopia, and children that spend more time with their eyes focused at near are more likely to develop it. As the number of children with access to smart phones, tablets, video games and more increases, it is expected that the myopia epidemic will continue to worsen.

The Risks

Though there are numerous eye health conditions associated with myopia, the four most prevalent are listed below.

Myopic Macular Degeneration: a condition where the portion of the retina responsible for clear, crisp, straight ahead vision deteriorates, leading to debilitating blind spots in one’s vision.

Retinal Detachment: an ocular emergency where the retina detaches from its normal position on the back of the eye. Without treatment this can cause permanent vision loss and/or blindness.

Glaucoma: a disease of the optic nerve that progressively reduces peripheral vision. Due to its lack of symptoms early on, this is often referred to as a “silent” cause of blindness.

Cataracts: a condition where the crystalline lens in the eye becomes opaque, blurring one’s vision and causing problematic glare. Treatment involves surgical removal of the cataract.

Current Treatment Options

There are several treatment options that can be used to slow or delay the progression of myopia over time. Unfortunately, none of the treatments will completely stop progression. But by reducing the rate of progression, we can lower one’s risk of developing one of the many eye health conditions associated with higher levels of myopia. Here are the current treatment options:

Orthokeratology (average rate of reduction 41%)

  • Similar to wearing braces, orthokeratology (ortho-k for short) involves wearing a special type of contact lens overnight while sleeping. The lens gently and temporarily reshapes the outer surface of the eye to change the way light focuses on the retina. Upon wakening, the patient removes the lens and will likely not need any glasses or contact lenses during the day in order to see. In addition to correcting vision, by changing the way light focuses on the retina, we can slow down growth of the eye and myopia progression.

Soft Multi-focal Contact Lenses (average rate of reduction 40%)

  • Wearing a specific type of multi-focal contact lens can also change the way that light focuses on the retina and slow down myopia progression. This type of lens is worn from the time of waking to bedtime.

Spectacle Lenses (average rate of reduction 20%)

  • Certain types of spectacle lenses can be used to reduce myopia progression, though they are the least effective method of them all. For patients who are not good candidates for the other options, 20% is still better than nothing!

Atropine Eye Drops (average rate of reduction 50%)

  • Diluted to 0.01%, these eye drops are dosed once daily at bedtime. The mechanism of action is not well understood at this time, but studies report good results in reducing myopia progression. This is often reserved for cases unresponsive to the above treatments in an attempt to avoid the long-term use of a pharmaceutical agent in children. It does have a good safety profile, but some children do experience side effects, such as mild pupil dilation, poor near vision, and light sensitivity.

Next Steps

If your child hasn’t had a comprehensive eye examination by an optometrist or ophthalmologist in the past year, it’s time to check in! Current standards recommend that the first eye exam for children occur between six and twelve months of age. Exam two should occur around age three, and exam three prior to kindergarten. Please remember that these are general guidelines, and it is recommended that you take the advice of your eye health professional when scheduling your child’s next visit.

 

Resources

 

  1. Aller, T. A. and C. Wildsoet (2006). “Results of a one-year prospective clinical trial (CONTROL) of       the use of bifocal soft contact lenses to control myopia progression.” Ophthal Physiol Opt 26(6).
  2. Bakaraju, R., P. Xu, X. Chen, M. Ma, S. Song, M. Jong, W. Li, S. Resnikoff and B. A. Holden (2015). Extended depth-of-focus contact lenses can slow the rate of progression of myopia. Association for research in Vision and Ophthalmology. Denver.
  3. Berntsen, D. A., L. T. Sinnott, D. O. Mutti and K. Zadnik (2012). “A randomized trial using progressive addition lenses to evaluate theories of myopia progression in children with a high lag of accommodation.” Invest Ophthalmol Vis Sci 53(2): 640-649.
  4. Chia, A., Q. S. Lu and D. Tan (2016). “Five-Year Clinical Trial on Atropine for the Treatment of Myopia 2: Myopia Control with Atropine 0.01% Eyedrops.” Ophthalmology 123(2): 391-399.
  5. Flitcroft, D. I. (2012). “The complex interactions of retinal, optical and environmental factors in myopia aetiology.” Prog Retin Eye Res 31(6): 622-660.
  6. Hiraoka, T., T. Kakita, F. Okamoto, H. Takahashi and T. Oshika (2012). “Long-term effect of overnight orthokeratology on axial length elongation in childhood myopia: a 5-year follow-up study.” Invest Ophthalmol Vis Sci 53(7): 3913-3919.
  7. PARSSINEN, O., KAUPPINEN, M. & VILJANEN, A. 2014. The progression of myopia from its onset at age 8-12 to adulthood and the influence of heredity and external factors on myopic progression. A 23-year follow-up study. Acta Ophthalmol, 92. 730-9.