An Overview of Myopia (Nearsightedness)

Written by Taylor Le and Edited by Josephine Chan

If you find yourself squinting when trying to read text from a distance or needing to get closer to someone to recognize who they are, you may likely have myopia. Myopia, more commonly known as nearsightedness, is a condition in which individuals cannot clearly see objects at a distance. 

Among children and young adults, myopia is the most common refractive error and occurs when the eye does not diverge and converge light properly to produce a clear image. In the case of myopia, the eye is elongated, resulting in a blurry image [1]. As a result, the focal point, where incoming light converges to produce an image, is located in front of the retina for individuals with  myopia. However, proper vision requires the focal point to be directly on the retina, where light converges on specialized photoreceptor cells that can then properly transmit signals to the brain. Myopia is a result of the light being focused too early, causing it to diverge instead of converge upon reaching the retina. 

As a means of correcting for myopia, prescription eyeglasses with concave lenses are commonly worn, as the curvature of its lens diverts and shifts the focal point back directly on the retina [2]. A 2016 meta-analysis of myopia by the American Academy of Ophthalmology indicated that in 2000, 22.9% of the global population had myopia. By 2010, the estimated number of individuals with myopia had increased to 28.3%. Similarly, the study projected that the proportion would increase to 34.0% in 2020 and ultimately to 49.8% of the global population by 2050 [3]. If similar trends continue to persist, myopia may eventually become a worldwide pandemic.

Individuals with severe myopia may have a higher risk of developing other eye-related diseases, such as macular degeneration, retinal detachment, cataracts, and glaucoma, resulting in worsening eye health and potential permanent vision loss [4] [5]. Eye development and growth proceeds rapidly and is highly prone to change during younger ages and puberty, but stagnates and remains relatively constant in one’s early 20s [6]. As a result, past and ongoing research on myopia mitigation is extremely prevalent, particularly in younger children. A 2015 study found that children who were exposed to an additional 40 minutes of outdoor activity during school were correlated with a significant decrease in the number of new myopia cases over the course of three years in comparison to those who were not exposed to the additional 40 minutes [7]. Besides additional outdoor activity, another method to potentially reduce the risk of developing myopia involves the use of Atropine eye drops, specialized eye drops that reduce eye elongation, in .05%, .025%, and .01% concentrations. A 2019 study analyzing the effects of Atropine drops suggested that a higher concentration was correlated with reduction of further myopia progression [8].

Although the meta-analysis presented predicts an increasingly prevalent proportion of new myopia cases in the future, it is imperative to consider that, while past data may indicate certain trends, they may not be entirely accurate and representative of the future if changes are implemented. Additionally, there may be other confounding factors involved in myopia progression, such as genetic and environmental influence, both of which have yet to be thoroughly examined. Regardless, the dramatic increase in myopia patients between 2000 and 2010 is concerning, depicting the necessity of more awareness and research on the mitigation and prevention of the condition.

References

1. “Myopia (nearsightedness).” American Optometric Association. www.aoa.org/healthy-eyes/eye-and-vision-conditions/myopia?sso=y#:~:text=Myopia%20occurs%20if%20the%20eyeball,30%25%20of%20the%20U.S.%20population. Accessed 23 Jan. 2021
2. “Nearsightedness and its Correction.” The Physics Classroom. www.physicsclassroom.com/class/refrn/Lesson-6/Nearsightedness-and-its-Correction. Accessed 23 Jan. 2021.
3. Holden, B. A., Fricke, T. R., Wilson, D. A., Jong, M., Naidoo, K. S., Sankaridurg, P., Wong, T. Y., Naduvilath, T. J., Resnikoff, S. (2016). Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmology, 123:1036–1042.
4. Fredrick, D.R. (2002). Myopia. BMJ : British Medical Journal, 324:1195–1199.
5. “Myopic Macular Degeneration.” (2015). Macular Disease Foundation Australia. www.mdfoundation.com.au/content/myopic-macular-degeneration. Accessed 23 Jan. 2021.
6. “Do Your Eyes Grow as You Age?” WebMD. www.webmd.com/eye-health/eyes-grow. Accessed 23 Jan 2021
7. He, M., Xiang, F., Zeng, Y., Mai, J., Chen, Q., Zhang, J., Smith, W., Rose, K., Morgan, I. G. (2015). Effect of Time Spent Outdoors at School on the Development of Myopia Among Children in China: A Randomized Clinical Trial. JAMA, 314:1142–1148.
8. Yam, J. C., Jiang, Y., Tang, S. M., Law, A., Chan, J. J., Wong, E., Ko, S. T., Young, A. L., Tham, C. C., Chen, L. J., Pang, C. P. (2019). Low-Concentration Atropine for Myopia Progression (LAMP) Study: A Randomized, Double-Blinded, Placebo-Controlled Trial of 0.05%, 0.025%, and 0.01% Atropine Eye Drops in Myopia Control. Ophthalmology, 126:113–124.