Myopia

The eyes are the sense organs of sight in our body. Each eye is a spherical-ball like structure and is referred to as the eyeball. The ability of the eye to see the object equally clear from various distances is called the power of accommodation. However, this power of accommodation can get defective at times. Like some times the eye is not able to see distant objects for eg. Highway signs clearly while sometimes it is not able to see near objects clearly. Here we are going to learn about the defect of the eye where distant vision is blurred while near vision is clear. Such a condition or abnormality of the eye is known as myopia. Let's study this defect of the eye (myopia)in detail.

What Is Myopia?

Myopia is an eye defect or common abnormality of the eye in which the near vision is clear while distant vision is blurred. This condition is known as myopia also it is called near or short-sightedness.

Retina is that part of the eye which provides a surface for image formation. In myopia what happens is light rays entering the eyes converge too soon and are brought to focus before reaching the retina hence the image cannot be formed on the retina.

Causes Of  Myopia

This eye defect called myopia can be caused basically due to the defected eye structure.

Structure of the eye causing myopia can have two defects:. 

• The eye lens becomes too convex or curved 

• Depth of the eyeball is too much i.e. eyeball lengthened from front to back. When the length of the eyeball is too long as compared to the focusing power of the lens of the eye and cornea. Because of this, the light rays focus at a point in front of the retina and not on the retina itself.

Because of the above mentioned defects in the eye structure, the light that enters our eye doesn't focus correctly. Hence, images are formed in front of the retina which is the light-sensitive part of our eye instead of being formed directly on the retina which causes blurred vision.

Myopia is also referred to as the refractive error.

In the above diagram, we can see that due to the eye lens being too convex or curved the image formation that should happen on the retina is happening in front of the retina. Thus, causing blurred vision of distant objects known as myopia.

Types of myopia:

• Simple Myopia - In this, the eye of a person is almost healthy, wearing glasses or contact lenses of suitable power can easily correct the defect and can correct the issue of a person's eye vision.

• High Myopia - High myopia is a severe form of myopia. When a person is diagnosed with myopia at a young age then with the growing age this defect becomes worse. High myopia increases the chances of development of other eye problems such as cataract, glaucoma etc.

• Pathological Myopia - This condition is also called degenerative myopia. It can also cause blindness and cannot be cured by lenses or glasses.

Myopia Correction

Myopia isn't a very complex disability. It can be corrected easily by wearing concave lenses. Concave lenses cause parallel rays of light to diverge before they converge and focus on the retina. 

Let's understand it more easily through a diagram:

Whenever asked what lens is used in myopia or what lens is used to correct myopia the answer should be the concave lens.

Now we will talk about the symptoms and also the treatment of this eye defect known as myopia.

Myopia Symptoms And Treatment

Symptoms of Myopia:

• If a person is myopic he or she will not be able to see the road signs and distant objects clearly but the nearer object will be visible to him/her clearly.

• Feeling of fatigue while playing sports or driving is also a symptom of myopia.

• When there is a need to close eyelids partially to see clearly or there is a need to squint is also a symptom of myopia.

• Eyestrain is caused due to myopia

• Headache is another symptom of myopia

• squinting and frowning.

• complications as a result of eyestrain.

Treatment of Myopia 

After a person is diagnosed with myopia he can have the following ways to treat this eye defect.

• Glasses and Contact Lenses - Most common treatment options for myopia is the usage of glasses and contact lenses with suitable power. The eye power for a myopic person is in negative numbers.

The custom lenses fit into frames and are worn as specs while the contact lenses are discs that sit on the surface of eyes.

• Orthokeratology - Orthokeratology is using overnight rigid contact lenses to reshape the cornea. It really works with the aid of pulling down the significant cornea, thinning the central corneal epithelium, thickening the mid-peripheral cornea, and producing a myopic shift in peripheral vision. This quickly reduces or eliminates refractive errors and decreases the want to put on contact lenses or spectacles in the daylight hours. Researchers observed that orthokeratology is as effective as atropine in delaying myopic progression.

Orthokeratology is a nonsurgical method for the treatment of myopia. This can be helpful in the treatment of a mild form of myopia. This treatment involves wearing a series of rigid contact lenses to reshape the cornea.

• Surgery - There are two types of surgery which can treat myopia. First one is laser surgery and the other surgery involves placing of the corrective lens inside the eye.