Understanding Refractive Errors: Protecting Your Eye Health

What Are Refractive Errors?

Refraction refers to the bending of light as it enters the eye. Under normal relaxed conditions, parallel light rays focus precisely on the retina. When light passing through the eye's optical system fails to focus accurately on the retina, it is called a refractive error — a category of conditions involving abnormal refractive states.

Classification of Refractive Errors

Based on the relationship between the focal point and the retina, refractive errors are classified into three types:

• Myopia (Nearsightedness): Parallel light rays focus in front of the retina.
• Hyperopia (Farsightedness): Parallel light rays focus behind the retina.
• Astigmatism: Light rays cannot form a single focal point.

Regular optometric examinations at qualified institutions are essential to determine the specific type and severity.

Causes of Refractive Errors

Refractive errors result from problems in the eye's refractive system, which mainly includes the cornea, crystalline lens, and vitreous body. Any structural issue in these components can affect image clarity. Common causes include:

• Genetic factors
• Prolonged use of electronic devices
• Lack of outdoor activity
• Picky eating habits
• Excessive sugar consumption

Diagnosis

Myopia

Patients experience blurred distance vision but relatively good near vision. Classification:

• Mild myopia: ≤ -3.00D
• Moderate myopia: -3.25D to -6.00D
• High myopia: > -6.00D

Hyperopia

• Low hyperopia: ≤ +3.00D
• Moderate hyperopia: +3.25D to +5.00D
• High hyperopia: > +5.00D

Associated conditions include: refractive amblyopia, esotropia, pseudopapilledema, and the need for hyperopic correction. Both distance and near vision may be blurred.

Astigmatism

Characterized by blurred vision at all distances, double images, and ghosting. The impact on vision depends on the degree and axis of astigmatism. High-degree or oblique-axis astigmatism has a greater impact on visual acuity.

Is Refractive Error Contagious or Hereditary?

Refractive errors are not contagious. However, they can be hereditary. Studies show that when both parents are myopic, the prevalence of myopia in their children can reach up to 90%.

Can Refractive Errors Be Cured?

Refractive errors cannot be cured. Continuous correction is needed, but treatment can only slow progression.

Symptoms

The most common symptom is blurred vision. Other manifestations include:

• Diplopia (double vision)
• Glare or halos around bright lights
• Headaches, eye fatigue, and soreness
• Difficulty concentrating during reading or computer use

Required Examinations

• Slit-lamp microscopy, corneal topography, axial length measurement, intraocular pressure, and fundus examination.
• Medical optometry using a phoropter for binocular refractive balance. Binocular visual function tests (accommodation, fusion, stereopsis) may also be necessary.

Correction Methods

Myopia Correction

Non-surgical: Primarily for adolescents whose eyes are still developing, including spectacle lenses and orthokeratology (Ortho-K) lenses. Ortho-K lenses are worn overnight and removed in the morning, typically providing clear unaided vision throughout the day.

Surgical: For patients aged 18 and above, options include personalized femtosecond laser surgery and ICL (Implantable Collamer Lens) implantation.

Hyperopia Correction

Mostly caused by congenital factors with the eyeball being too short. There is no effective intervention to change this. Early eye examinations and establishing a visual health development file are important. When refractive error exceeds a certain threshold, especially with amblyopia, timely intervention with glasses or visual function training is needed.

Astigmatism Correction

The key is timely examination and establishing a visual health development file. Based on the degree of astigmatism and eye alignment, corrective lenses may be necessary to prevent impaired visual development in children.

Early Detection and Treatment

When facing refractive errors, we must not be careless. Early intervention is crucial for protecting eye health.