Myopia: Types, Causes & Symptoms

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According to an estimate by the American Optometric Association, about 30% of the population in the United States is affected by myopiaChildren, particularly of school-going age, mostly face this problem, when they have to focus on writing on the board. They complain of blurred vision or difficulty to see things that are at a distance and their studies can suffer or they can develop headaches.

What is Myopia?

Myopia is the scientific name given to nearsightedness. Nearsightedness is the condition where a person is not able to see objects clearly that are far away. It is considered as a refractive type of error in the eye. The focus of distant objects falls in front of the retina, rather than on the surface of the retina, resulting in the inability to clearly see things that are beyond a certain distance.

Research shows that under normal conditions, it is more difficult to focus on objects that are closer than it is to focus on objects that are far away. This stress causes the eye to elongate gradually to allow for the eye to adjust itself to focus on objects that are near. This process will eventually make the eyes incapable of seeing things which lie at a distance. Scientifically, this process is called a ciliary muscle spasm, a condition in which the eye becomes elongated to accommodate for focusing on objects that are close.

Some ophthalmologists argue that myopia can be the root cause of permanent damage to the eye causing blindness in the long run. That being said, even in the short run, it can cause trouble.

Myopia

Types

The most common types of myopia include the following.

  • Simple myopia: It is one of the most common types. In this condition, the eye becomes elongated.
  • Nocturnal myopia: Also called night myopia, it is a condition in which a person’s eyes experience difficulty in seeing in low light conditions. However, their daytime vision can be normal. It commonly occurs because of pupil dilation and aberrations, thereby resulting in the myopic condition.
  • Pseudomyopia: This is another type of myopia associated with an excessively close focus on work. This is mostly seen in young people. A growing problem is happening with handheld video games, since children are spending more and more time focusing on those games that are very close, resulting in an increase in this condition.
  • Degenerative myopia: As the name suggests, degenerative myopia becomes worse over time and is regarded as one of the predominant causes of blindness. It is also known as pathological myopia and can result in retinal detachment and glaucoma.
  • Induced myopia: It occurs due to exposure to medications, high levels of glucose in the body, or nuclear sclerosis. Usually, it can be reversed. However, if the exposure is continuous and happens for a long time, it can result in the condition becoming permanent.

Symptoms

The symptoms of this disorder include:

  • Regular headaches
  • Light sensitivity at nighttime
  • Eye strain because of the pressure exerted while trying to focus
  • Strained focus leads to a squint in the eyes

Causes

Some of the major causes of myopia are:

  • Close up work: Working on something at a very close range to the eyes is one of the major factors for an increased myopia risk. In other words, people who constantly focus on things close to them can lose the ability to see things at a distance. This was proven in a controlled experiment conducted in Alaska, United States. In Alaska, there were hardly any cases of this problem before the introduction of a compulsory education system. 10 years after the initiation of the education system, there were reportedly 75% of myopic cases in children.
  • Low light conditions: Working in the dark or in low light conditions is also one of the causes of myopia. Due to the lack of optimum light, the eyes have to exert pressure trying to focus on objects, especially reading. This extra effort can translate into myopia.
  • Long-term use of corrective lenses: Research indicates that myopic conditions can be aggravated by the use of corrective (minus) lenses for a long period of time.
  • Diabetes: Type II diabetes is also a contributing factor for such eye diseases. In diabetes, an excess amount of sugar in the blood hampers the flow of blood. In this case, the blood flows slowly through optical nerves. In other words, objects appear blurry to diabetics, forcing them to exert their eyes to focus even more.
  • Hereditary factors: According to a study, heredity is also one of the important factors that contribute to myopia.
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