An abnormal elongation in the myopic eye may lead to increased vision-threatening complications. Control myopia progression early for better long-term eye health.
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āMy kidās myopia continues to worsen, and he needs a new pair of glasses every year. Would he lose vision?ā A concerned parent asked in a facebook patient support group.
Myopia, also known as nearsightedness, is a condition in which nearby objects appear clear, but distant objects appear blurry. This is due to an eyeball that is longer than normal or a cornea that is too curved. These abnormalities result in an image being focused in front of the retina rather than directly on it. When the photoreceptors in the eye translate the light signals to the brain, they are interpreted as a blurry image, a phenomenon known as myopic defocus.
Even though myopia is an inconvenience that can be easily corrected with eyeglasses, contact lenses, or surgery, high myopia increases the likelihood of severe but uncommon vision-threatening complications, such as myopic macular degeneration (MMD), retina detachment, cataracts, and glaucoma. These complications may lead to legal blindness or vision loss if not timely treated.
High myopia is defined as more than -6 diopters.
Hence, correcting vision for clear sight and controlling myopia to reduce the risks of vision-impairing complications are important goals of myopia management.
Why the elongation of the myopic eye increases the risk of vision-impairing complications?
A recent review studyĀ found that people living with myopia had 100 fold higher risk of MMD, a three-fold higher risk of retina detachment or cataracts, and an almost two-fold increase in the risk of glaucoma. Further, the higher the refractive errors, the higher the chances of these complications.
InĀ another study presented at the Association for Research in Vision and Ophthalmology 2022, researchers found refractive error changes were closely correlated to axial lengths in myopic children. For every millimeter increase, the refractive error increases by 2.04 diopters.
It makes sense. In high myopia, the abnormal elongation of the eyes may overstretch and reduce the thickness of the retina, causing retina cells to die slowly. The strain also leads to the retina becoming more prone to tears or even retinal detachment.Ā
Furthermore, the biomechanical stretch fromĀ the anatomical changes in myopic eyes may induce excessive production of a protein called vascular endothelial growth factor (VEGF), which may lead to abnormal, leaky blood vessel growth ā the onset of myopic macular degeneration.
As for why the risk of glaucoma was increased, medical experts speculated thatĀ the increase in the axial length of the eye led to structural changes to the optic disc, causing damage to the nerve cells in the optic nerve head.Ā Ā
Lastly, two possible explanations exist for why increasing axial length in the eyeball increases the risk of cataracts. Firstly, the elongated eyeball may lead to insufficient nutrient delivery to the back of the lenses, causing them to lose clarity. Secondly, the biomechanical stretch and damage to the retina cells lead to the production of various biochemical by-products, which subsequently cause a cloudy lens.Ā Ā Ā
It is important to note that not everyone with high myopia develops these complications. But we should be aware of the risks and take steps to protect our childās precious vision.
What can I do to reduce the risks of vision-threatening complications?
If your child has been diagnosed with myopia, the myopia control treatment objective is to prevent the condition from worsening, in other words, to stop the abnormal elongation of the eyes.Ā
You can help your child control their myopia through treatments and lifestyle modifications.Ā
- Go out and play: Send your child out of the house to get two (2) hours of daylight daily. Some appropriate activities include playing outside with neighbors, sports, gardening, trail hiking, picnic, or playing in the snow. (Learn more about how daylight helps prevent myopia from worsening.)
- Take breaks:Ā If your child spends a lot of time on near-vision activities, take breaks to give their eyes a rest. Try the 20-20-20 rule recommended by medical society: every 20 minutes, take a 20-second break and look at something 20 feet away. (Note:Ā A recent study suggested that this may not be enough. I am considering 5 min break for every hour of near-vision activities for my son.)
- Wear glasses or contacts as prescribed:Ā If you have been prescribed glasses or contacts, wear them as directed.Ā
- Myopia control treatments: Several well-studied therapies are available to prevent myopia from progressing. Keeping myopia under control could reduce the risk of vision-threatening complications. Each treatment has its benefits and risks; discuss with your doctor what may be the most appropriate for your child. (Learn more about myopia control treatment options)
Key takeaways
Glasses and contact lenses can help correct vision by focusing light on the right spot of the retina. However, the ability to see clearly may not translate to a reduced risk of vision-threatening complications driven by the increased axial eye length.Ā
By tackling the abnormal elongation early, you can help your child maintain good eye health and have clear sight for years to come.
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