What is refractive error?

With normal vision, light reflected from an object enters the eye through the cornea (the curved, transparent surface that protects the front of the eye). Because the cornea focuses (refractors) these light rays pass through the eye's natural lens, where they are converged to focus at a sharp point on the retina (the back layer of the eye that contains sensitive cells). with light). Retinal cells convert light rays into electrical impulses that are sent to the brain (via the optic nerve) and processed to form images.
Refractive error is a phenomenon in which light from an object does not reach the retina but is in front or behind or many points on the retina, causing the image of the object to be blurred and we will not be able to see the object clearly.

2. Causes of refractive error
The main reason is that due to the rapid development of technology, people are increasingly dependent on electronic devices with blue light that is harmful to the eyes, especially children's early exposure to gadgets. technology at an increasing rate. These refractive errors will affect and cause difficulties in daily biology as well as in studying, working and daily activities.


3. Symptoms of refractive errors
Blurred or distorted vision
Difficulty focusing on near or far objects
Squint to read
Eye strain or fatigue
If you experience any of the above symptoms, you should see your doctor for a general eye exam.


4. Effects of refractive error
There are 4 types of refractive errors: Myopia, Farsightedness, Astigmatism, Presbyopia, of which myopia accounts for more than 70% of refractive errors in Vietnamese children. In 2010, there were only about 1.8 billion people in the world with refractive errors, but by 2020 this number has doubled. In developing countries, where people are less interested in regularly checking their vision health, this rate is especially increasing rapidly and much higher. In Vietnam alone, the rate of myopia has reached over 38%.

Understanding Refractive Error: A Clear Explanation
What is Refractive Error?

Refractive error is a common eye condition that affects how light is focused on the retina. This can result in blurred vision and difficulty seeing objects clearly. It occurs when the shape of the eye prevents light from being accurately focused on the retina, leading to vision problems. There are different types of refractive errors, including myopia (nearsightedness), hyperopia (farsightedness), astigmatism, and presbyopia.

Myopia: Difficulty Seeing Objects Far Away

Myopia, also known as nearsightedness, is a refractive error that makes it challenging to see objects far away. People with myopia can usually see close objects clearly but struggle with distant vision. This occurs because light rays focus in front of the retina instead of directly on it, resulting in blurred distance vision.

Hyperopia: Difficulty Seeing Objects Up Close

Hyperopia, or farsightedness, is a refractive error where individuals have trouble seeing objects up close. In hyperopia, light rays focus behind the retina instead of on it, leading to blurry close-up vision. People with hyperopia may experience eyestrain and headaches when trying to focus on nearby objects.

Astigmatism: Distorted or Blurred Vision

Astigmatism is a refractive error caused by an irregularly shaped cornea or lens in the eye. This results in distorted or blurred vision at all distances. Astigmatism can accompany myopia or hyperopia and is corrected through eyeglasses, contact lenses, or refractive surgery.

Presbyopia: Age-Related Vision Changes

Presbyopia is an age-related refractive error that occurs when the natural lens of the eye loses flexibility, leading to difficulty focusing on close objects. As people age, the lens becomes less elastic, making it challenging to read or perform tasks that require near vision. Presbyopia is typically corrected with reading glasses or multifocal lenses.


In conclusion, refractive error is a common eye condition that affects millions of people worldwide. Understanding the different types of refractive errors, such as myopia, hyperopia, astigmatism, and presbyopia, is crucial in managing and correcting vision problems. If you experience symptoms of refractive error, consult an eye care professional for a comprehensive eye examination and appropriate treatment options.