Myopia: Causes, Symptoms, Types & Tests

Myopia, also known as nearsightedness, is one of the most common vision problems affecting people worldwide. Characterized by difficulty seeing distant objects clearly, myopia often begins in childhood and may worsen with age. Its prevalence has risen dramatically in recent decades, partly due to lifestyle changes like increased screen time and reduced outdoor activity. While myopia can usually be corrected easily with glasses, contact lenses, or refractive surgery, high myopia may increase the risk of more serious eye diseases later in life.

Myopia

Myopia is a refractive error where light entering the eye focuses in front of the retina rather than directly on it. This makes distant objects appear blurry, while close objects can often be seen clearly.

In most cases, myopia occurs because:

• The eyeball is too long from front to back.
• The cornea (the clear front part of the eye) or the lens is too curved.

As a result, light rays bend incorrectly, leading to blurred distance vision.

Myopia is typically diagnosed in childhood or adolescence and may stabilize in adulthood, though in some people it continues to progress.

Causes of Myopia

Myopia develops due to a combination of genetic and environmental factors:

1. Genetics:

• Children with one or both nearsighted parents are at higher risk.
• Family history strongly influences the likelihood of developing myopia.

2. Lifestyle and environment:

• Excessive near work (like reading, using smartphones, or working on computers) is linked to increased risk.
• Reduced time spent outdoors, especially in childhood, is associated with faster progression of myopia.
• Inadequate lighting and poor visual habits may contribute.

3. Eye structure:

• Abnormal elongation of the eyeball or excessive curvature of the cornea/lens causes light to focus in front of the retina.

Symptoms of Myopia

Common signs and symptoms include:

• Blurred distance vision: Difficulty seeing road signs, classroom boards, or television clearly.
• Clear near vision: Reading or using devices up close may still be easy.
• Eye strain: Especially after focusing on distant objects.
• Headaches: Due to squinting or eye strain.
• Frequent squinting: To try to see more clearly.
• Difficulty seeing while driving, especially at night (night myopia).
• Needing to sit closer: For example, moving closer to the TV or the front of the classroom.

In children, signs might include:

• Sitting very close to screens.
• Holding books very near to the face.
• Complaining of blurred vision or headaches.
• Reduced academic performance due to poor distance vision.

Types of Myopia

Myopia can be classified into several types, depending on its characteristics and severity:

1. Simple myopia:

• The most common type.
• Usually develops in childhood and stabilizes in early adulthood.
• Mild to moderate in degree.

2. High myopia:

• Severe nearsightedness (typically more than -6.00 diopters).
• Increases the risk of serious eye complications like retinal detachment, glaucoma, cataracts, and myopic macular degeneration.

3. Degenerative or pathological myopia:

• Rare but serious.
• Progressive elongation of the eyeball.
• Leads to severe vision impairment and structural changes in the retina and choroid.

4. Night myopia:

• Difficulty seeing distant objects in low light or darkness.
• Often due to the eye's natural inability to focus accurately in dim light.

5. Pseudomyopia:

• Temporary blurring of distance vision caused by eye muscle overuse.
• Often linked to prolonged close-up work.

Tests Used to Detect Myopia

Eye care professionals use several tests to diagnose and measure myopia:

1. Visual acuity test:

• Measures how clearly you see letters on a chart from a standard distance (often 20 feet).
• Determines the degree of vision impairment.

2. Refraction test:

• Uses a phoropter and trial lenses to measure the exact lens prescription needed for clear vision.

3. Retinoscopy:

• The doctor shines a light into the eyes to observe how light reflects off the retina.
• Helps estimate refractive error.

4. Autorefractor test:

• An automated instrument that provides an initial measurement of refractive error.

5. Slit-lamp examination:

• Checks the health of the front and back of the eye to rule out other issues.

6. Fundus examination:

• Looks at the retina, optic nerve, and other internal structures for signs of high myopia complications.

Conclusion

Myopia is one of the most common and manageable vision problems, but it deserves attention. Beyond the inconvenience of blurred distance vision, high or progressive myopia can increase the risk of eye diseases that threaten long-term vision. The good news is that early detection through routine eye exams, protective lifestyle habits (like more time outdoors), and appropriate corrective measures (glasses, contact lenses, or refractive surgery) can help manage myopia effectively. Parents should watch for signs of vision problems in children, while adults should keep up with regular eye exams to track any changes.

Frequently Asked Questions (FAQ’s)

1. What is myopia?
Myopia, or nearsightedness, is when distant objects appear blurry while close objects remain clear.

2. Can myopia go away on its own?
No, myopia usually doesn’t resolve; it often stabilizes after adolescence.

3. How is myopia treated?
With glasses, contact lenses, or refractive surgeries like LASIK.

4. Does screen time cause myopia?
Excessive near work may contribute, especially in children.

5. Can myopia be prevented?
While not entirely preventable, spending more time outdoors may slow its progression.

6. What is high myopia?
Severe nearsightedness that increases the risk of eye diseases.

7. At what age does myopia start?
Often begins in childhood, typically between ages 6 and 14.

8. Is myopia hereditary?
Yes, family history increases the risk.

9. Can myopia get worse over time?
Yes, especially during childhood and teenage years.

10. Does myopia affect near vision?
No, near vision usually remains clear; the problem is with seeing distant objects.