What exactly is myopia?
Nearsightedness (myopia) is a refractive defect that causes fuzzy distance vision. It is the leading cause of vision impairment in those under the age of 40. Myopia normally develops in childhood, but it can deteriorate until early adulthood. This is known as myopia progression.
By the age of 15, over half of children with progressive myopia have a stable prescription. Approximately three-quarters stabilize by the age of 18, and nearly all stable by the age of 24. Myopia, on the other hand, can quickly proceed to extreme myopia if not managed. In adulthood, high myopia can cause sight-threatening issues.
The number of persons suffering from myopia is increasing at an alarming rate. In the year 2000, approximately 25% of the world's population was myopic. According to research, about half of the world's population will be nearsighted by 2050.
What causes myopia?
Myopia (nearsightedness) occurs when the eye focuses on light rays in front of the retina rather than on it. This causes distant objects to appear fuzzy.
Several distinct aspects play a role in appropriately focusing light onto the retina:
- The distance between the front and back of the eye.
- The corneal and lens shapes
- The position of the lens and the cornea within the eye in relation to one another.
Myopia can be caused by minor differences in any of these factors.
Children's eyes grow and develop swiftly during their initial years of life. During this time, the shape of the cornea and lens, as well as the length of the eye, are in balance, resulting in sharp vision.
This is known as emmetropization. Emmetropia occurs when there is no refractive defect in the eyes.
The majority of youngsters are born with farsightedness (hyperopia). This is due to the fact that the eyes are still abnormally short from front to back at birth.
The emmetropization process continues until the youngster is about 6 to 8 years old. Most children have modest hyperopia at this period, with only a tiny fraction having myopia.
The development and evolution of myopia
In some circumstances, the procedure is repeated. When this happens, the eyes go from emmetropia to myopia. The eyeball may get overly long, or the corneal or lens curvature may become too steep. The lens may shift too close to the cornea in rare situations.
Early infancy is frequently the greatest period of myopia growth. Several variables influence the development and progression of myopia at this age, including:
- Spending time outside
- Activities around the workplace (like reading and digital screen time)
A person is three times more likely to be nearsighted if one of their parents is nearsighted. If both parents are nearsighted, they may be at a six-fold increased risk.
Myopia is frequently classified into two types based on its cause: '
- Axial myopia occurs when the eyeball is abnormally long from front to back (the axial length). It is the most prevalent cause of myopia, particularly in children.
- If the cornea or lens is overly curved, it might cause refractive myopia. It can also happen if the lens is too close to the cornea, however this is uncommon.
Some people can have both axial and refractive myopia.
Symptoms of myopia
People with myopia have trouble seeing distant objects well, such as traffic signs. They typically have stronger vision when performing close tasks such as reading and computer use. Therefore, myopia is also known as nearsightedness.
Other myopia symptoms include:
- Moving closer to objects to see them clearly or squinting the eyes
- Having difficulties with activities that necessitate strong distant vision, such as driving or participating in sports
- Strain on the eyes
If you notice any of these symptoms while wearing your glasses or contact lenses, make an appointment with your optometrist. You could require a stronger prescription.
Management of myopia
Myopia management encompasses all areas of eye care that a person with myopia may require. Its goal is to correct impaired vision, regulate myopia progression, and reduce the risk of problems associated with excessive myopia.
Management of myopia entails:
- Diagnosis and early detection
- Correcting and controlling myopia in a timely manner
- At-home procedures such as the 20-20-20 rule and screen time restriction
Detection and diagnosis of myopia
Early myopia detection and treatments are critical in decreasing myopia progression. However, many children who are nearsighted do not show visible symptoms and do not complain of them. If their eyesight has always been fuzzy at a distance, they may not notice that someone else's is crisper.
This is only one of the reasons why childhood eye exams are so crucial, even if you haven't detected any signs of myopia or other vision difficulties. The following is the suggested timetable for eye checkups for all children:
- At 6 months, the child has his or her first eye test.
- Another child between the ages of three and five
- Another in their first few years of primary school
- Throughout the academic year
Children who have a history of myopia risk or who already have myopia may require more frequent eye exams.
If you or your child requires corrective lenses, the eye doctor will advise you on the strength of the correction required. Myopia prescriptions are denoted by a minus sign (-) followed by a number. A greater number suggests a higher degree of myopia.
Low myopia is defined as -0.50 to -5.75, whereas high myopia is defined as -6.00 or more. High myopia is a matter for concern because it can result in major consequences. High myopia complications include the following:
- Posterior subcapsular cataracts
- Macular degeneration that is myopic
- Detachment of the retina
If you are at risk for high myopia, your eye doctor will address this with you. During your exam, they will also look for issues connected to high myopia.
Correction of myopia
Myopia can be treated optically or surgically. Prescription eyeglasses or contact lenses are examples of optical approaches. Refractive surgery is one of the surgical procedures.
Some people with nearsightedness must always wear their glasses or contact lenses. Others may only wear them when performing specific tasks, such as driving or looking at a chalkboard.
Following your eye exam, your eye doctor will discuss the precise amount of correction you require. They will also advise you on how frequently you should wear your corrective lenses.
Refractive surgery can significantly reduce or eliminate the need for glasses or contact lenses. It is, however, not a corrective option until a person's myopia prescription has stabilized. The following are some of the more prevalent refractive procedures:
Nearsighted people are growing increasingly. As a result, there is a great deal of interest in discovering techniques to reduce myopia progression in children. It is especially critical because extreme myopia might result in major vision issues.
Myopia is typically treated with single-vision glasses and contact lenses as the first line of defence. These regular lenses, however, are ineffective at controlling myopia progression.
According to new research, using properly constructed multifocal lenses can reduce the progression of myopia. There is evidence that these multifocal lenses help slow axial eye elongation. In other words, they have the ability to slow the rate at which the eye becomes longer.
Effective myopia control treatments for adolescents with increasing myopia include:
Myopia control glasses - Certain bifocal, progressive (PAL), and other specifically constructed eyeglass lenses can help to decrease the growth of myopia.
Contact lenses for myopia control - Both soft multifocal contact lenses and orthokeratology have shown success in decreasing myopia progression. Presbyopia patients were the first to benefit from multifocal soft contact lenses. Newer types of these lenses are being utilized to control myopia, with positive results. Orthokeratology, commonly known as corneal reshaping therapy, is a type of corneal reshaping therapy. Overnight, special rigid gas permeable (RGP) contact lenses are worn to temporarily restructure the cornea. This allows for clear eyesight during the day without the use of glasses or contact lenses. Orthokeratology has been shown in studies to be useful in slowing the progression of myopia.
Atropine eye drops - For a long time, eye doctors have used atropine eye drops to help treat myopia. However, a high quantity of atropine in the drops causes adverse effects such as light sensitivity and headaches. Low-dose atropine eye drops, fortunately, can also reduce the progression of myopia in youngsters. The smaller dose can reduce progression at the same rate as the higher dose while causing far fewer negative effects. Some children, however, do not respond well to atropine drops.
Factors of lifestyle - According to research, spending at least 90 minutes per day outside minimizes the chance of getting myopia. Parents should also encourage their children to take frequent pauses while reading or watching television outside of school. The precise association between near work and myopia is unknown. However, some research indicates that continuous close labour may be a risk factor for the development and progression of myopia. Holding books, screens, and other near work too close to the eyes may also play a role.
Myopia control techniques can be employed singly or in tandem. Your eye doctor will be able to advise you on which approaches will have the most impact on myopia progression.
Prepared by Optometrist Muhamad Aurangzeb Khan, O.D BOptom (Hons), Management & Science University.
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