In the era of digital technology, school refractive errors are increasing significantly in countries around the world, including Vietnam. According to estimates by the World Health Organization, there are currently about 150 million people with uncorrected refractive errors, children account for about 9% of them. The Asian region has the highest rate of refractive errors in the world, especially China, Taiwan, and Singapore, where refractive errors account for about 80% to 90% of students at all levels.

Of the four types of refractive errors, myopia is considered the most common in Vietnam today. According to a 2016 study, the prevalence of myopia in the population today accounts for about 23% of the population, and it is estimated that by 2050, this rate may reach 50% of the total world population with 9.8% high-altitude nearsightedness. In Vietnam, according to many studies, the rate of myopia is relatively high, and tends to increase rapidly in the future.

Myopia causes visual impairment at an alarming rate, affecting quality of life. In addition, the development of myopia into high myopia will cause other complications such as retinal degeneration, detachment, retinal tear, etc. Therefore, it is advisable to bring children and relatives to the doctor to screen for refractive errors. in general and myopia in particular is really necessary.

Define

Myopia occurs when the axis of the eyeball is too long or the cornea (a transparent surface at the front of the eye) is too curved, causing light entering the eye to not focus properly on the retina, resulting in blurred vision. blur. As a result, people with myopia can see near objects more clearly than far away.

The danger elements

In addition to the above causes, nearsightedness also tends to be hereditary. If a parent is nearsighted, the risk of a child having myopia is about 6 times higher (in case both parents have it), or 3 times (if only one parent has it). Besides, myopia also tends to develop in people who have a habit of using near vision a lot (reading books, using phones, computers, drawing pictures,…) ^[10]

Symptom

Symptoms of nearsightedness include:

• Blurry vision
• Blurry vision at night
• When studying or watching TV, children often come close to watch or read
• Frequent squinting, blinking
• Tears, or sleepiness
• Fear of light

Diagnose

To diagnose refractive errors, there are many methods to perform, but the main principle is still to use machines and devices to measure the force of focusing light into the eye. The diagnostic procedure includes:

• Ask for medical history
• Visual acuity measurement (far, near in each eye, and binocular) with and without glasses
• Objective refractive measurement (using pupillary scintillation method, automatic refractor, …)
• Subjective refractive measurement (using test glasses, binocular balance, etc.)
• Adjust the glasses appropriately
• Single glasses out
• Checking the condition of binocular vision, eye movement, accommodation
• General medical examination
• Advice on appropriate adjustment methods (frames, contact lenses, …)
• Patient education

Some methods of correcting/treating myopia

The goal of the treatment/correction for myopia patients is to make the eyes no longer blurred, more comfortable, binocular vision is also improved, complications of myopia are monitored, and control. 

There are 4 common methods of correcting/treating myopia:

Optical adjustment

Frame glasses

Advantages of frame glasses

• Low cost
• High safety (for materials with good impact resistance)
• Additional prisms can be combined to treat binocular vision conditions
• Framed glasses do not cause infections on the eyes like contact lenses
• Suitable for most ages

Cons of glasses frames:

• Sometimes not suitable for some people to play sports, be active
• Perimeter viewing area is limited
• Some undesirable optical effects may cause visual fatigue when the frame is not properly centered

Contact lenses

Advantages of contact lenses:

• More aesthetic than frame glasses
• Better treatment in cases of children with refractive errors (with significant difference in binocular refraction)
• The viewing area is not narrowed
• More suitable for people who are active, play sports, …

Disadvantages of contact lenses:

• May cause some inflammation, infection in the front part
• More expensive than frame glasses
• Difficult to use; When using, it must be carefully consulted by medical staff

Ortho-K gas permeable rigid contact lenses (Orthokeratology)

Ortho-K is a hard contact lens with a special structure, capable of flattening the central corneal area, changing the way light rays enter the eye, thereby reducing myopia. These glasses are usually worn at night when you go to bed, and removed in the morning when you wake up. After removing the glasses in the morning, the patient will not need to wear glasses and still see clearly for a certain period of time. This method also has another application in controlling the development of myopia in children.

Advantages:

• High aesthetics
• Limiting the lack of oxygen to the cornea when worn, partially reducing eye complications caused by contact lenses
• The results of the treatment are also reversible, meaning that after stopping wearing glasses for a while, the cornea will return to its original state – an advantage over other types of refractive surgery.

Defect:

• There is still a certain risk of eye infection, infection
• The cost of this type of glass is also relatively higher than other types of contact lenses.

Refractive surgery

Refractive surgery methods use many different methods to change the refractive power of the cornea, helping light to focus accurately on the retina, so that the patient will be able to see clearly.

There are many popular refractive surgery methods in Vietnam: LASIK, Femto – LASIK, ReLEx SMILE, etc.

Advantages:

• Short surgery time
• Short recovery time
• Highly aesthetic

Defect:

• The cost is quite high
• Much depends on the skill of the surgeon
• There is a risk of some complications after surgery