Myopia - The Mystery
-Dr.Pavan K. Verkicharla, BS Opt. Ph.D
Published on 23rd March 2019
Let me start this with a disclaimer that this article is based on “my perspective” on myopia.
The title says it all. It is still “unclear” why myopia occurs, when it occurs, how it occurs, who are at risk of developing or having progressive high myopia. Does that mean, we ignore it or take action to fight it?
As Optometrists, we are the most responsible individuals of the eye care profession for the management of myopia.
Did you know?
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The prevalence of myopia worldwide has increased drastically in the last couple of decades
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Approximately (5 billion) half the world’s population is expected to have myopia by 2050
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Myopia has a multi-factorial etiology with a lot of associated “X" (unknown) factors
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Both environmental and genetic factors have been associated with the onset and progression of myopia
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We need to think of refraction in the periphery (off-axis refraction) as a relative hyperopic defocus in the peripheral part of the eye poses a high risk of myopia development and progression
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Myopia presents healthcare services with a considerable public health burden
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Myopia increases the risk of vision-threatening conditions such as chorioretinal degenerations and retinal detachment with increasing degree of myopia (few myopia lesions are noted even in mild and moderate degree of myopia too)
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It is promising to know that there are anti-myopia strategies to counteract myopia and its progression
Being an Optometrist, what are we supposed to do?
The answer is simple and straight forward. We need to “manage” myopia, instead of just correcting it.
In spite of knowing all the above points, we just tend to give single vision spectacles or contact lens and see them off from our clinics. Note that in a few occasions, we tend under-correct which is reported as a bad choice based on a couple of research studies.
Here are a few options and its efficacy based on multiple publications. I am quoting the network meta-analysis article by Huang et al. that shows the effectiveness of different interventions to slow down the progression of myopia in children.
Under-correction with spectacles or contact lens - Very Bad. It actually aggravates for axial elongation.
Full correction spectacles - No use. In such cases, anti-myopic strategies would be helpful when you see someone who is progressing by >0.75 D per year.
Bi-focal Spectacles - Okay good
Anti-myopia Spectacles - Okay good
Multi-focal or bi-focal peripheral defocus lenses - Very good
Orthokeratology - Very Good - Keep in mind to do regular monitoring to ensure that there are no ocular complications due to overnight wear of lens
Atropine 0.01% - Very good – Keep in mind that is pharmacological management and need to be prescribed by an Ophthalmologist. Kindly refer to a good pediatric ophthalmologist
Atropine 1% - Very good - But keep in mind about the pupillary dilation, glare, arrested accommodation, and other side effects
Time outdoors - This strategy is known to work great only when the child has not developed myopia yet – Preventive strategy only.
Note: Increasing time in the outdoors is of no use if the child has already developed myopia. There is strong evidence coming out already to say that time outdoors cannot help in controlling or arresting the progression of myopia. Now, why being outdoors doesn’t control myopia progression is still not clear. It is possible that the myopic eye might perceive blur/defocus signals a bit different than that of an emmetropic eye.
Common question: Now that we say time outdoors is good for either preventing myopia or delaying the onset of myopia, does that mean that prolonged reading has no role in myopia development?
The recent evidence from animal and human studies indicates associations between outdoor time and myopia. However, the interaction of the role of light and near work in altering the ocular properties during myopia development is still not clear. I strongly believe that there is much more than just the light itself and that is the reason in most of the research publications you see statements like “There are a number of possible mechanisms by which time outdoors could protect against the development of myopia with the hypothesis mostly related to dopamine release in the retina, uniform dioptric visual field, exposure to specific spectrum of light such as blue, vitamin-D and the last but not the least, relaxed accommodation (not doing near work or reading).” So point to note is that one of the explanations for outdoors being protective for myopia (either preventing myopia or delaying the onset of myopia) is “hey – you are outdoors and which means you are not reading or writing or not performing prolonged near activity”. Keep in mind that myopia has multi-factorial etiology, therefore, it is not wise to completely write off the role of near work on myopia development and needs further research for drawing meaningful conclusions in this space.
To conclude, managing myopia or myopia progression is beyond prescribing singe vision lenses. There are multiple options to control myopia progression. It should be emphasized that the anti-myopia strategy the child should get to counteract myopia progression should be decided on a case to case basis considering various "X"-factors, but not just based on just the routinely performed on-axis refraction.
Keep in mind the 4 M's of Myopia Mantra:
Multi-factorial nature of myopia causation
Measure the 'X' factors i.e. estimate/quantify the possible myopic risk factors
Monitor the refractive error (progression) closely (3-6 monthly to see the changes) +
Manage with appropriate anti-myopia strategy (see the list of options above)
Details on how these anti-myopia strategies work and guidelines for myopia management will be published in part 2 of this article.
“Nearly 1 billion myopes at risk of myopia‐related sight‐threatening conditions by 2050 – time to act now” – Holden et al. 2015
Dr. Pavan Kumar Verkicharla is a Scientist at the L V Prasad Eye Institute (LVPEI) researching both basic and applied aspects of myopia mainly investigating epidemiology, pathogenesis/causation of myopia/pathologic myopia and anti-myopia strategies. Pavan holds a Bachelor’s degree in Optometry from LVPEI's Bausch & Lomb School of Optometry (BITS). His doctoral research at the Queensland University of Technology-Australia and the post-doctoral research at the Singapore Eye Research Institute-Singapore led to the development and validation of novel devices/techniques to improve our understanding about myopia risk factors (quantification of retinal shape and wearable light tracker to increase the outdoor time for myopia control). As a young researcher, Pavan invests his time understanding the pathophysiology of myopia and aim to develop a cost-effective anti-myopia strategy that can be used worldwide. He recently secured two research grants from the Government of India: “Inspire Faculty Award” from the Department of Science and Technology; and Early Career Research Award from the Science and Engineering Board.
Pavan loves playing cricket, mentoring students and driving on the roads of Hyderabad. Besides all, he is the current working president of ALO.
Key References:
1. Myopia Special Issue, Investigative Ophthalmology & Visual Science, 60, 3, M1-M19 (2019)
2. Huang J, Wen D, Wang Q, et al. Efficacy Comparison of 16 Interventions for Myopia Control in Children: A Network Meta-analysis. Ophthalmology
123, 697-708, (2016).
3. Dolgin E. The myopia boom. Nature. Mar 19 2015;519(7543):276-278.
4. Holden BA, Jong M, Davis S, Wilson D, Fricke T, Resnikoff S. Nearly 1 billion myopes at risk of myopia‐related sight‐threatening conditions by 2050– time to act now. Clin Exp Optom. 2015;98(6):491-493.