What is myopia?

Short Answer

Myopia, also called near-sightedness, is an eye defect in which a person can see nearby objects clearly but distant objects appear blurred. This happens because the image of a distant object forms in front of the retina instead of exactly on it.

Myopia occurs when the eyeball becomes too long or when the eye lens becomes too powerful. It can be corrected using concave lenses, which shift the image back onto the retina and allow the person to see distant objects clearly.

Detailed Explanation :

Myopia

Myopia is one of the most common vision defects found in people of all ages, especially school-going children and working adults who read or work on screens for long hours. In myopia, a person can see near objects clearly, such as reading books, writing notes, or looking at a mobile screen. However, distant objects like the blackboard, road signs, number plates, or far-away buildings appear blurry. This difficulty arises because the eye is unable to focus light correctly on the retina for distant vision.

Myopia is also known as near-sightedness because the person’s “near vision” remains normal, but the “far vision” becomes weak.

Causes of Myopia

Myopia occurs mainly due to two reasons:

  1. Elongated Eyeball

In many cases, the eyeball becomes longer than normal from front to back.
Because of this extra length:

  • Light rays entering the eye converge too early.
  • The focused image forms in front of the retina.
  • Far objects appear blurred.

This is the most common cause of myopia.

  1. Overly Powerful Eye Lens

Sometimes the eye lens becomes too curved or too strong in its focusing power.
This causes:

  • Excessive bending (refraction) of light
  • Image forming before the retina
  • Blurred distant vision

Both conditions lead to the same problem: the image does not reach the retina.

How Myopia Affects Vision

In a normal eye:

  • Light rays from distant objects enter almost parallel.
  • These rays focus perfectly on the retina.
  • Clear images are formed.

In a myopic eye:

  • The rays focus in front of the retina.
  • The retina receives an out-of-focus image.
  • Distant objects look dull, fuzzy, or unclear.
  • Near objects remain clear because they require more focusing, which the myopic eye can handle.

This is why a myopic person finds reading easy but struggles in outdoor vision or classroom viewing.

Symptoms of Myopia

Common signs that indicate myopia include:

  • Difficulty in seeing distant objects
  • Squinting the eyes to see far things clearly
  • Headaches after looking at distant objects
  • Eye strain during outdoor activities
  • Sitting very close to the TV or classroom board
  • Holding books too close while reading

These symptoms show that the eye is trying harder to focus on distant objects.

Correction of Myopia

Myopia can be corrected using concave lenses (also called diverging lenses).

A concave lens:

  • Spreads out (diverges) the incoming light rays
  • Moves the image backward
  • Allows the rays to focus exactly on the retina
  • Restores clear distant vision

Concave lenses have a negative power (−).
The more severe the myopia, the higher the negative power needed.

Why Concave Lenses Are Used

Concave lenses reduce the focusing power of the eye.
Since a myopic eye has excessive focusing, a concave lens helps balance it by:

  • Slightly diverging the ray before it enters the eye
  • Preventing early convergence
  • Ensuring the image forms on the retina

This optical correction gives the person normal vision.

Myopia in Daily Life

Many schoolchildren with myopia cannot read the board unless they sit in the front row.
Drivers with myopia have difficulty reading distant road signs.
People with myopia may remove their glasses for reading because they can see near things clearly.

Myopia can affect studies, work, safety, and confidence if not corrected.

How Myopia Develops

Myopia may develop due to:

  • Genetics (runs in families)
  • Excessive screen time
  • Long hours of reading without breaks
  • Poor lighting
  • Less outdoor activity
  • Incorrect posture while studying

Children who spend more time indoors are more likely to develop myopia.

Treatment and Prevention

While myopia cannot always be prevented, the following habits can help control it:

  • Take breaks after every 30–40 minutes of reading
  • Maintain correct posture
  • Reduce mobile and computer screen usage
  • Spend more time outdoors
  • Ensure good lighting while studying
  • Regular eye check-ups

For correction:

  • Eyeglasses with concave lenses
  • Contact lenses
  • Laser surgery (LASIK) in adults

These methods help maintain healthy vision.

Conclusion

Myopia is an eye defect in which a person can see near objects clearly but distant objects appear blurred. This defect occurs because the image of far objects forms in front of the retina due to an elongated eyeball or an overly powerful eye lens. Myopia is corrected using concave lenses that help shift the image onto the retina. Understanding myopia helps in early detection, proper correction, and healthier eye habits.