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In today’s article, we will be introducing a new topic called Myopia, a common refractive error affecting vision.
Have you ever noticed that you could see the text on your phone screen clearly but were unable to see the writing on the blackboard at school? This difference in clarity indicates that you might have myopia (nearsightedness).
Myopia affects the way the eye focuses light. Myopic people can easily see things that are close to them, while things in the distance appear blurry. Knowing the causes and mechanisms of myopia may help understand better how vision works.
How Does Normal Vision Work?
To understand myopia, we must first understand how the eye focuses light.
Light goes through the eye’s cornea (a transparent curved surface in front of the eye), then it goes through the pupil and the lens, where it reaches a light-sensitive layer known as the retina at the back of the eye.
The cornea, along with the lens, works on bending light through a process called refraction, where light rays get bent as they pass through a medium. In proper vision, these formations work in unison to ensure that the light focuses on the retina properly.
The retina then converts the light into electrical impulses, which pass through the optic nerve and reach the back of the brain. The brain interprets these impulses into images.
The location where light is focused is especially important. If light does not focus on the retina correctly, the resulting image can appear blurry.
What is Myopia?
Myopia refers to a refractive disorder where people are able to see clearly things that are nearby but not those that are far away. It’s caused by the light that enters the eye being concentrated in front of the retina instead of reaching it directly. This can happen for many reasons.
In myopic people, the eye is often longer than normal from front to back. In other cases, the cornea is sometimes curved too steeply, and it causes the eye to bend incoming light too much.
A good analogy is to think of the retina as a screen where images are being formed. In a healthy eye, the image is focused right on the screen. In a patient with myopia, the image is formed somewhat in front of the screen and is not as clear.
That’s why people with myopia can read the text in a book without a problem but may have difficulty reading a billboard on the street.
What are the Symptoms of Myopia?
The primary symptom of myopia is having problems with vision at far distances. An individual suffering from myopia can struggle to see objects that are far, but they can see on things close to them without much difficulty.
For a student, this can be especially noticeable. A student might be capable of reading from their notebook, however, it will be difficult for them to read notes on the board.
Apart from that, there are some additional symptoms of this condition which include:
- Frequent squinting when looking at things from long distances.
- Occurrence of headaches due to eyesight problems.
- Experiencing eyestrain.
- Incapacity to see properly when driving, especially at night.
- A need to watch TV from a closer distance than normal.
Children and teenagers may not always recognize that their distance vision is blurry. If their vision has gradually changed, they may assume that what they see is normal.
What Causes Myopia?
Myopia is caused by the eye’s focusing system causing light to converge in front of the retina.
One major factor is the distance between the eyeball’s front and back that may account for this problem. Longer eyes mean that light rays converging ahead of the retina.
Additionally, the cornea shape has some influence too. When the cornea is curved too much, it causes excess bending of light rays.
Also, genetics plays a very important role. If a child has one or more myopic parents, there is a greater likelihood they will also develop myopia. However, genetics alone is not enough to explain myopia development, since environmental and behavioural factors also play a role, particularly during childhood.
Why is Myopia Becoming More Common?
The rise of myopia around the world among young people is becoming more common nowadays. A worldwide study indicates that 22.9% of the population was diagnosed with myopia in the year 2000, and it is predicted to jump up to around 49.8% by 2050. In other words, almost half of the world may face this problem.
This increase is likely related to a range of genetic and environmental causes. For instance, a lot of close work, such as reading, studying, or being on a digital device, is linked to myopia, whereas a lack of outdoor time could also mean increased risk. However, this should not be understood as saying that reading or using a phone causes myopia. Scientists are still researching this interrelationship, but it appears that spending more time outside is especially beneficial to children by decreasing their risk of developing myopia.
How is Myopia Diagnosed?
Myopia is diagnosed during an eye checkup. The optometrist can find out how well the patient sees from various distances as well as evaluate the refractive error of the eye.
One of the most crucial components of an eye checkup is a refraction test. As a part of this test, multiple lenses are placed in front of the patient’s eyes so that they may identify which lens eyes can see through most clearly.
Generally, a myopia prescription will feature a number that shows a reduction in the correction necessary. The scale of correction also depends on how strong the myopia is.
For instance, the numbers in a prescription may be −1.00 or −3.00. The bigger the negative number in this case, the stronger the required correction.
Eye examination provides information not only on a person’s eyesight but also about the state of their eyes in general.
How is Myopia Corrected?
Myopia can usually be corrected effectively. The goal of correction is to move the focal point of incoming light onto the retina.
Eyeglasses
Eyeglasses are the easiest and most common method of correcting this vision issue. Myopia lenses are concave and have a negative power.
These lenses change the way incoming light is bent before it enters the eye. This allows the eye to focus the light more accurately onto the retina.
Contact lenses
As an alternative, myopia can also be treated by the use of contact lenses. Contact lenses are applied to the eye directly and are able to change the way in which light enters the eye.
Refractive Surgery
Another option available in adult life is the procedure of refractive surgery, for instance, LASIK or PRK . These techniques change the shape of the cornea and help focus the light correctly.
Refractive surgery is generally considered for adults whose eyes have reached a stable prescription. It is not simply another type of glasses and is not appropriate for everyone.
Can Myopia Get Worse?
Myopia can vary as the eye grows, especially during the childhood and teenage years.
For some individuals, the degree of their myopia remains fairly mild and stable. But for others, their prescription becomes increasingly stronger as the eye continues to grow.
This is why it is especially important to have eye care examinations done consistently during childhood and teenage years.
Changes in the prescription help the eye experts to know how the vision is evolving through monitoring its development and the associated eye diseases. Higher levels of myopia can also lead to a higher risk of some eye problems later in life, since a longer eyeball means extra pressure on certain structures of the eye.
Can Myopia be Prevented or Slowed?
Some cases of myopia are impossible to prevent due to genetic factors. However, there are several methods suggested by eye specialists to lower the chances of developing myopia in children and to also slow the progression of the problem.
One of the most frequently recommended methods is spending more time outdoors. Time spent outdoors has been proved beneficial for healthy eye development.
Children suffering from myopia that is getting worse may be suggested some specific control methods. There are many myopia control methods, including special contact lenses, eyeglasses, and prescribed medication as listed previously. Unlike ordinary glasses, these are not only intended for better vision, bu these tools are designed with the purpose of slowing down the development of myopia.
Every person is unique, and the right choice depends on the specific characteristics of the patient.
Conclusion
Overall, Nearsightedness or Myopia is a condition characterised by the blurring of distant objects due to the light rays not being focused properly on the retina.
There are a number of reasons such as length of the eyeball, shape of the cornea, genetic and environmental influences that can lead to Myopia. Myopia is mostly common at childhood or adolescence when the eyeball is developing.
Myopia is fairly easy to fix by simply wearing glasses or contact lenses. For adults, surgery may also work depending on their intensity of Myopia.
The most important thing you should keep in mind is that blurry vision in distance is not normal. Vision can change or progress over time and is especially prominent during adolescence. The best way to maintain your eye health is through scheduling regular examinations.
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References
- American Academy of Ophthalmology. (n.d.). Myopia. https://www.aao.org/eye-health/diseases/what-is-myopia
- American Optometric Association. (n.d.). Myopia. https://www.aoa.org/healthy-eyes/eye-and-vision-conditions/myopia
- Cleveland Clinic. (n.d.). Nearsightedness (myopia): What it is, causes & treatment. https://my.clevelandclinic.org/health/diseases/8579-nearsightedness-myopia
- 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(5), 1036–1042. https://pubmed.ncbi.nlm.nih.gov/26875007/
- Mayo Clinic. (n.d.). Nearsightedness. https://www.mayoclinic.org/diseases-conditions/nearsightedness/symptoms-causes/syc-20375556
- National Eye Institute. (n.d.). Nearsightedness. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/nearsightedness-myopia
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