What Is Myopia?

Overview

Myopia, also known as nearsightedness, is a prevalent visual condition often identified in individuals under the age of 20. It primarily impacts the ability to see distant objects clearly, while near objects can still be seen with relative ease. For example, tasks like reading grocery store aisle markers or identifying road signs from a distance become challenging.
There are two main types of myopia: high myopia and degenerative myopia. High myopia is an uncommon type of severe nearsightedness that is usually inherited. It occurs when a child's eyeballs grow longer than they should or when the cornea is excessively curved. High myopia is typically defined as having a refractive error greater than -6. It can progressively worsen over time and will normally stabilize between the ages of 20 and 30. 

Degenerative myopia, on the other hand, is a relatively rare but severe form of myopia that usually starts in early childhood. It causes damage to the retina and is one of the leading causes of legal blindness.¹

Causes of myopia

The aetiology of myopia, or nearsightedness, is still not fully understood, but experts believe it to be a combination of genetic and environmental factors. Normally,  when one or both parents have myopia, their children are more likely to develop the condition. The interplay between inherited predisposition and lifestyle choices can contribute to its onset. For instance, engaging in extensive close-up work such as reading or using computers for prolonged periods may increase the likelihood of developing myopia.²

Signs and symptoms of myopia

If you have myopia, you may experience some of the following symptoms:

• Distant objects appear blurry or unclear
• Headaches
• Eye strain
• Squinting
• Fatigue while driving, playing sports, or looking at things far away

In children, there are additional signs of myopia to watch out for:

•  Poor academic performance
•  Reduced attention span
•  Holding objects close to the face

Management and treatment for myopia

The primary objective in addressing myopia is to enhance vision by ensuring that light focuses properly on the retina. This can be achieved through the use of corrective lenses or refractive surgery. It is also important to regularly monitor for potential complications associated with myopia, such as glaucoma, cataracts, and retinal detachment.

There are two main types of prescription lenses: eyeglasses and contact lenses. Prescription lenses work by compensating for the curvature of the cornea or the elongation of the eye. 

Refractive surgery, such as LASIK, is another option to reduce dependence on glasses or contact lenses. During LASIK surgery, a laser is used to reshape the cornea, resulting in better vision. Normally, light is precisely refracted onto the retina at the back of the eye, but with myopia, hyperopia, or astigmatism, the light is incorrectly bent, resulting in blurred vision. Reshaping the cornea can correct this refractive error.

Another surgical procedure, Small Incision Lenticule Extraction (SMILE), involves cutting a small disk-shaped piece of the cornea without creating a flap or removing the epithelium. This lenticular is then removed through a small incision in the cornea.

However, it's important to note that surgical treatments are not suitable for everyone with myopia. Surgery is typically recommended when myopia progression has stabilized. 

In addition to these treatment approaches, there are ongoing efforts to develop more effective methods to slow down or halt the progression of myopia, especially in children and adolescents. Some of the promising therapies include the following: 

Atropine

Atropine, a medication that inhibits muscarinic receptors, has been studied extensively for its potential to control myopia progression. It is commonly used to dilate the pupil during eye examinations. Low doses of atropine eye drops may help slow down the progression of myopia.³

Orthokeratology

This therapy involves wearing rigid contact lenses only at night to temporarily reshape the cornea. The lenses are not worn during the day. 

Lifestyle changes

Spending more time outdoors during childhood, adolescence, and early adulthood may reduce the risk of developing myopia.

Diagnosis of myopia

Myopia can be diagnosed through standard eye exams conducted by an eye care provider. While commonly detected in childhood, it can also manifest in adults due to visual stress or diabetes.

For adults, the eye care provider will evaluate the focusing ability of your eyes and determine the need for corrective lenses. The evaluation begins with a visual acuity test, where you'll be asked to read letters on an eye chart. A retinoscope and phoropter may also be used.

Children's eyes are examined during routine visits to the paediatrician. Ideally, the first eye exam should be done before the age of 1. If no obvious eye problems are detected, it is advisable to schedule another eye exam before starting kindergarten. Since myopia tends to run in families, early testing is especially important if there are any family members with vision issues. If any vision problems are noticed by you or your paediatrician, your child may be referred to an optometrist or pediatric ophthalmologist. During a child's eye examination, the eye care provider will physically examine the child's eyes and check for a regular light reflex.

Risk factors

Ethnicity is one of the risk factors associated with myopia progression, with higher prevalence and incidence rates observed among Asian populations compared to European Caucasians. Studies have shown that Singapore has reported an annual myopic progression rate of approximately -0.80 diopters (the unit used to measure eyeglasses prescriptions) whereas European Caucasians exhibit rates closer to -0.50 diopters per year.^4,5

Age is a significant determinant of incident myopia, with less hyperopic refraction at a younger age being a strong predictor. The highest risk for myopia progression lies in individuals with myopic refraction of at least -1.25 diopters during the transition period around 6 to 7 years of age. This group not only tends to have a greater amount of myopia but also experiences a faster rate of progression and elongation of the eyeball.⁶ Although it is logical to expect a higher overall myopia level in younger patients, the precise reasons for the accelerated rate of progression remain unknown.

Research has demonstrated that parental myopia, even in one parent, increases the risk of developing myopia in children. In fact, if both parents are myopic, there is a more than six-fold increased risk of juvenile-onset myopia. Parental myopia not only predisposes children to myopia but also raises the likelihood of progressive myopia.

The impact of gender on myopia is still debatable. The COMET study found no significant difference between individuals assigned male at birth and the individuals assigned female at birth whereas the National Health and Nutrition Examination Survey indicated a higher prevalence of myopia amongst individuals assigned female at birth aged 20-40 compared to the  individuals assigned male at birth. However, these trends were not consistently observed across other age groups.^7,8

Complications

Nearsightedness can lead to a range of complications from mild to severe:

• Reduced quality of life: Uncorrected nearsightedness can hinder your ability to perform daily tasks and enjoy activities fully. It can also pose a safety risk to yourself and others, particularly when driving or operating heavy machinery
• Eyestrain: Untreated nearsightedness can cause persistent eyestrain and headaches
• Other eye problems: Severe nearsightedness increases the risk of severe eye conditions including retinal detachment, glaucoma, and cataracts

FAQs

Can myopia be prevented?

Adopting a healthy lifestyle and practising eye relaxation techniques can be a natural approach to reducing myopia. These methods help to relax the eye muscles and prevent them from becoming tense.

How common is myopia?

In the United States and Europe, myopia affects approximately 30% to 40% of adults, while in Asian young adults, the prevalence can reach up to 80% to 90%.

Is myopia genetic?

Common myopia is a complex condition influenced by numerous genes, making its inheritance pattern unclear. However, the risk of developing myopia is higher for immediate family members (such as siblings or children) of individuals affected by the condition compared to the general population.

When should I see a doctor?

It is recommended to schedule regular visits to an ophthalmologist, preferably once a year.

Seek immediate medical attention if you experience any of the following symptoms:

• Sudden appearance of numerous floaters, which are tiny specks or lines that seem to drift through your visual field
• Flashes of light in one or both eyes
• A grey shadow resembling a curtain that covers part or all of your visual field
• A shadow in your peripheral vision (outer or side vision)

These warning signs may indicate a retinal detachment, where the retina detaches from the back of the eye, requiring prompt medical intervention.

Summary

Myopia, also known as nearsightedness, is a prevalent visual condition that primarily affects a person's ability to see distant objects clearly. While the exact causes of myopia are still not fully understood, a combination of genetic and environmental factors is believed to contribute to its development. Various treatment options, including corrective lenses and refractive surgery, are available to improve vision for those with myopia. Ongoing research is focused on finding more effective methods to slow down or halt the progression of myopia, especially in children. Regular eye examinations and early intervention are crucial in managing myopia and preventing potential complications. It is essential to prioritise eye health and seek prompt medical attention for any concerning symptoms related to vision.