What is Myopia? How is Myopia Formed?

What is Myopia? How is Myopia Formed?

Myopia, commonly known as nearsightedness, occurs when the parallel light rays from a distant target, located 5 meters away, pass through the eye's optical structures in a relaxed state and converge in front of the retina, forming a diffuse ring instead of a clear image. As a result, distant objects appear blurry. Myopic individuals can compensate for this by getting closer to objects, increasing the angle of focus, and magnifying the images on the retina to see nearby objects clearly.

Both environmental and genetic factors are the two main causes of myopia, with environmental factors having a greater impact. The development of most myopia is related to excessive near work during the eye's developmental stage, mainly concentrated in the school-age period. During this phase, children and teenagers engage in intensive near work, coupled with modern lifestyle habits (frequent use of computers, smartphones, and other electronic devices), living environments with limited space and distant viewing distances, as well as lighting and writing postures, all of which contribute to prolonged near vision. As a result, the eyeball elongates, and the axial length increases, causing the incoming light to focus in front of the retina and leading to myopia.

What are the Hazards of Myopia in Children and Adolescents?

Myopia can be classified into low (-3.0D or below), moderate (-3.0D to -6.0D), and high (-6.0D or above) degrees. Low and moderate myopia can affect the healthy growth, normal learning, and daily life of children and adolescents, while high myopia can lead to degenerative changes in the eye's fundus, such as myopic maculopathy, retinal degeneration, and retinal detachment. Moreover, myopia can significantly impact defense construction. Currently, the high prevalence of myopia in children and adolescents negatively affects industries that require high visual demands, such as the military, aerospace, and precision manufacturing. Additionally, several studies have confirmed a certain genetic predisposition to high myopia, which can adversely affect the quality of the population.

Is Myopia a Disease?

Myopia is not a disease; rather, it is a refractive state of the eye. The essence of myopia is akin to an out-of-focus camera, caused by optical imbalance between the lenses (cornea and crystalline lens) and the film (retina) among various components. Low and moderate myopia can be considered as a result of human adaptation to the environment. In modern life, people frequently use computers, smartphones, and other electronic devices for work, leading to prolonged near-vision use. Therefore, mild and moderate myopia can be regarded as a manifestation of the body's adaptive ability and does not fall into the category of diseases. However, high myopia, if not accompanied by abnormal fundus conditions and other vision-affecting complications, and if the corrected distant visual acuity is not lower than 1.0, cannot be considered a disease. Nevertheless, myopia can cause various complications, such as myopic maculopathy, cataracts, and retinal detachment, which are diseases affecting vision.

Is Myopia Hereditary?

Heredity is an important factor in the development of myopia and influences its occurrence to a certain extent. Low and moderate myopia, also known as simple myopia, is generally caused by unfavorable visual habits after birth. Wearing glasses can correct vision to normal levels, and the genetic risk for this type of myopia is relatively small. On the other hand, high myopia, also known as progressive myopia, involves the continuous elongation of the eyeball's axial length with age, accompanied by degenerative changes in the retinal fundus. Even with glasses, vision cannot be fully corrected to normal, and serious complications affecting vision may occur. The genetic risk for this type of myopia is relatively higher.

Genetic factors play a significant role in the occurrence and development of myopia in children and adolescents. Existing research indicates the following: when both parents are myopic, the incidence of myopia in their children is higher; when one parent is myopic, the incidence is moderate; and when neither parent is myopic, the incidence of myopia in their children is lower. Additionally, myopia is influenced by a combination of genetic and environmental factors. If both parents are not myopic, but the child is subjected to excessive visual stress, myopia can still occur.

What are the Complications of Myopia?

Although myopia itself is not a disease, it can cause various eye-related complications, many of which can lead to blindness. The most common complications of myopia are six-fold:

1. Retinal Detachment

Myopia can cause degeneration and thinning of the peripheral retina, coupled with vitreous liquefaction and increased activity, leading to retinal detachment, which is the most common complication of myopia.

2. Vitreous Liquefaction and Degeneration

After myopia develops, the eye's axial length increases, but the vitreous remains the same size. This causes the vitreous to fail to fill the entire space inside the eye, leading to liquefaction and opacification, resulting in floaters.

3. Leopard Spots in the Fundus

Dilation of the posterior pole of the eye causes elongation of the choroidal capillaries, affecting the nutrition of the retinal pigment epithelium, resulting in pigment loss and the appearance of leopard spots in the choroidal vessels.

4. Glaucoma

Glaucoma is characterized by increased intraocular pressure and damage to the optic nerve. Inflammatory changes or the use of corticosteroid eye drops can lead to poor eye tolerance and increased intraocular pressure, making the optic nerve vulnerable to damage.

5. Strabismus and Amblyopia

Strabismus refers to a condition in which the eyes cannot simultaneously focus on a target due to dysfunction of the extraocular muscles. Amblyopia refers to a decrease in the best-corrected visual acuity of one or both eyes during visual development due to abnormal visual experience.

6. Retinal Hemorrhage or Macular Degeneration

Neovascularization of the retina can lead to retinal hemorrhage, and repeated hemorrhage can cause local scarring, resulting in macular degeneration and permanent damage to vision.

What is Pseudo-Myopia? Can It Be Cured?

Pseudo-myopia is a form of functional myopia caused by tension in the ciliary muscle that adjusts the lens inside the eye. Since children and adolescents' eyes are in a growing and developing stage, their ciliary muscles have strong adjusting capabilities. If they spend a lot of time focusing on near objects, combined with poor eye hygiene or excessive accommodation, it can lead to tension and spasms, resulting in blurred distance vision and the appearance of myopia. Pseudo-myopia can be alleviated after a period of rest or using medications to paralyze the ciliary muscle. However, if not managed properly and the eyes continue to be used at close range for an extended period, the axial length of the eyes can elongate, leading to irreversible axial myopia.

Is Vision Related to Nutrition? How Should Vision Be Protected through Nutritional Supplements?

Studies have shown a correlation between myopia formation and diets high in sugar and protein, as well as lacking certain trace elements. Additionally, research has found a negative correlation between vitamin D levels in the body and the length of the eyeball, indicating that vitamin D may play a direct role in myopia formation. Currently, it is believed that myopia formation may be related to the lack of calcium and chromium in the body, as these elements play a role in maintaining eye pressure and eye wall hardness.

To protect vision, it is advisable to consume foods rich in vitamin A, such as animal liver, egg yolks, and carrots; foods containing vitamin B2, such as mushrooms and sweet potatoes; and other foods that supply essential vitamins for eye health, such as fruits, vegetables, and coarse grains. Additionally, it is essential to minimize or avoid consuming harmful substances for the eyes, especially avoiding smoking and excessive alcohol consumption. Also, it is best to consume fewer stimulant-rich foods, such as garlic, onions, peppers, and peppercorns.

Protecting vision through dietary habits