Myopia, popularly known as nearsightedness, is a refractive error that results in the inability to view distant things. According to studies, more than 40 percent of people in the United States have myopia.
Myopia usually appears in children aged between 6 and 14 years. It might worsen during adolescence although it normally improves between the ages of 20 and 40 years. In rare cases, a severe form of nearsightedness known as degenerative myopia can lead to deteriorating distant vision in adulthood.
The power of an eye is measured in diopters where myopia is denoted with a minus power of an eye.
Myopia is of two types:
- Low myopia: -0.50 to -3.0
- High myopia: -6.0 and greater
What causes myopia?
During the normal development of the eye, all the components develop simultaneously so that the light is focused precisely on the retina, resulting in sharp vision. Myopia develops when the normal development of the eyeball is disrupted or altered.
Myopic eyes are either elongated in form, stretching longer than they should, or have overly curved cornea. It affects where light is focused within the eye. Instead of focusing directly on the retina at the rear of the eye, light from distant objects focuses in front of the retina, making distant things look hazy.
Is high myopia dangerous?
High myopia, also known as severe myopia, occurs when the degree of refractive error is more than six diopters. An excessive increase in the size of the eye causes it. High myopia not only necessitates the use of glasses with a high prescription but also increases the risk of other potentially dangerous disorders.
The retina thins and weakens as the eye length increases, increasing the risk of hemorrhage, retinal lesions, or even retinal detachment. Moreover, the degeneration of the gelatinous liquid that fills the eye (vitreous body) can cause floaters.
In extreme cases of myopia, the macula, the most essential region of the retina, may gradually degrade, resulting in a progressive and permanent loss of vision. High myopia may also increase the risk of glaucoma and the development of early cataracts.
When does myopia onset occur?
Myopia usually develops in infants and children but can also develop in adults.
- Myopia in infants and young children
- Myopia advances rapidly in young children because their eyes grow faster.
- Young children with myopia may require a stronger prescription and are more likely to develop other eye issues in the future.
- Myopia in newborns and toddlers can be difficult to detect because they do not realize or cannot verbalize the condition.
- Childhood-onset myopia
- It is usually caused by the eyeball growing too fast or continuing to expand after the age of 10 to 12 years, usually when eye growth should stop.
- The rate of nearsightedness has risen among children in recent years owing to the excessive use of portable technology and decreased time spent outdoors.
- Adult-onset myopia
- It is typically caused by strained or tired muscles required for focusing the eyes up close.
- This may be due to an increase in work that necessitates a close view or focus, such as university studies or working with displays.
- It could also be due to inadequately corrected vision, such as not wearing glasses when necessary or using the incorrect prescription.
What are the risk factors for myopia?
Extensive studies are still being conducted to determine the exact cause of myopia. However, it may be caused by the following:
- Lifestyle factors, such as spending more time focusing on objects that are close to the eyes, for example:
- Playing with gadgets
- Watching TV by sitting close to it
- Diseases, such as diabetes
- Many genes may be linked to the development of myopia and no clear pattern of inheritance is known.
- The risk of developing is high if an immediate family member is affected.
- A mutation in a single gene can cause high myopia, and it exhibits a clear pattern of inheritance.
- It can either be autosomal dominant (a gene from one parent is enough to cause the condition) or autosomal recessive (genes from both parents are necessary to cause the disease).
- Autosomal recessive is an X-linked disorder with mutations on the X-chromosomes and is most common among men.
- Men are more often affected by X-linked disorders than women.
What are the symptoms of myopia?
Myopia symptoms differ from person to person. Nearsightedness often begins around adolescence and worsens over time until the eye is completely developed.
You may spot myopia in young children by checking for particular indications, such as:
- Difficulty reading or seeing distant objects clearly (they may sit close to the TV or request to sit toward the front of the class to see better)
- Straining or squinting the eyes to see better
- Complaining of recurrent headaches and often massaging their eyes for relief
If you suspect you or a loved one has myopia, an eye exam will confirm if you are shortsighted, and you will be prescribed contact lenses or glasses to help correct your vision.
How is myopia diagnosed?
People with myopia have difficulty seeing the whiteboard, movie screen, television set, or other distant things. Your optometrist conducts an eye examination and subjects you to various tests to determine if you need a prescription for myopia.
The diagnostic tests optometrists use to diagnose myopia include:
- Refraction test: You are asked to read a chart placed at a particular distance and mirrors are placed in front of your eyes to make your vision clear.
- Dilater pupillary exam: Pupils are dilated with special drugs and the retina is checked for diseases.
- Slit lamp examination: A bright light is used to check for retina, corneal injuries, dry eyes, cataracts, and glaucoma.
- Visual field test: Determines your peripheral vision.
- Visual acuity test: Is done to test the clarity of near and far vision.
- Retinal tomography: An imaging test to determine the condition of the retina.
- Corneal tomography: An imaging test that determines corneal curvature.
- Ultrasound: Ultrasound waves are used to detect hemorrhages, tumors, or cataracts in the eye.
- Fluorescein angiogram: A dye is injected into the body, and blood circulation in the eye is checked to detect diseases such as retinal detachment, diabetic retinopathy, and macular degeneration.
How is myopia treated?
Myopia therapy aims to compensate for your eyes' inability to focus on distant things and, in youngsters, halt myopia's growth.
Monitoring for potential side effects of myopia, such as glaucoma, cataracts, retinal tears and detachments, and damage to central retinal regions, is also part of myopia management.
- Glasses and contact lenses
- An optometrist can prescribe you glasses and contact lenses with a choice of prescriptions that cover a range of distances and can accommodate variances in vision between your eyes.
- However, they cannot stop the eye from becoming longer or fix the abnormal corneal curvature that causes poor vision.
- It is a technique that involves wearing stiff cornea-shaping contact lenses at night.
- These contact lenses can restructure the cornea while in use.
- The cornea momentarily retains its new shape even after removing the lenses, allowing you to see correctly without lenses.
- Wearing contact lenses at night allows you to enjoy clear vision throughout the day without needing glasses.
- Refractive surgery
- This surgery eliminates the need for spectacles or contact lenses.
- Your cornea can be reshaped with laser refractive surgery to erase your nearsightedness prescription.
- If laser surgery is not an option, implantable contact lens surgery is a safe, quick, and effective procedure for permanently correcting vision.
- Children should not get refractive surgery because their eyes are still growing and their prescription is changing.
- Phakic intraocular lenses
- These lenses are placed into the eye to replace the natural lens.
- They do not take the place of the natural lens.
- They require no maintenance because they reside permanently inside the eye.
- These lenses are intended for extreme shortsightedness where other treatment approaches may be ineffective.
- This therapy is not appropriate for everyone, especially those with known glaucoma.
Myopia Testing (Nearsightedness): https://myvision.org/myopia/testing
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