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At least 100 million in India need spectacles but have no access

  • September 29, 2023
  • Posted by: OptimizeIAS Team
  • Category: DPN Topics
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At least 100 million in India need spectacles but have no access

Subject : Science and Tech

Section :Msc

Context:

  • The World Health Assembly, in its meeting, resolved to implement an “integrated people-centered eye care” project.

Global status of people with vision impairment:

  • According to the WHO, at least 2.2 billion people function with compromised eyesight and at least a billion of these were preventable with access to eye care.
  • Around 90% of those with vision impairment or blindness live in low- and middle-income countries.
  • Fourth international conference on ‘Eye health in a changing world’ organised by the India Vision Institute, a non-governmental organisation.

The common defects of the eyes are:

  1. Myopia
  2. Hypermetropia
  3. Presbyopia
  • These are called the refractive defects because they are caused by incorrect refraction of light rays by the eye lens.
  1. Myopia
  • It is also called shortsightedness
  • In Myopia:
    • Person is able to see nearby objects clearly but is not able to see faraway object
    • Image of Faraway objects is formed in front of retina
    • Far point of person is nearer than infinity
  • Causes of Myopia
    • Excessive curvature of eye lens (eye lens become more curved)
    • Eyeball becomes elongated
  • Correction of Myopia
    • It is corrected by using concave lens of suitable power
    • It helps to form image on the retina

  1. Hypermetropia
  • It is called long sightedness (or Hyperopia)
  • In Hypermetropia
    • Person is able to see faraway objects but are not able to see nearby objects
    • Image of Nearby objects is formed behind the retina
    • Near point of person is beyond 25 cm
  • Causes of Hypermetropia
    • Eyeball becomes too small
    • Focal Length of Eye lens is too long
  • Correction of Hypermetropia
    • It is corrected by using convex lens of suitable power
    • It helps to form image on the retina

  1. Presbyopia
  • It is the defect in which person is not able to see nearby objects clearly
  • It is formed in old persons whose ciliary muscles become weak with age Hence, they lose their power of accommodation.
  • Causes
    • Weakening of Eye muscles
    • Decrease in Flexibility of Eye lens
  • Correction of Presbyopia
    • it is also corrected with the help of convex lens (just like Hypermetropia)

In both Presbyopia and Hypermetropia:

  • A person cannot see nearby objects clearly but can see far away objects clearly.
  • The difference is in their causes:
    • Presbyopia is caused due to loss of Power of Accommodation
    • Hypermetropia is caused due to abnormal shape of the eyeball or abnormal shape of the eye lens

What are Bifocal Lens?

  • It is a lens whose upper part consists of concave lens and inside part for convex lens
  • It is used in case of those patients who are suffering from both myopia and hypermetropia

Progressive lens:

  • Progressive lenses are a type of lens which have no differentiating lines between the focal distances. These have three different levels of focal distances ranging from distance to near.
  • One looks through the top portion of the lens to see far-away objects, the middle to focus on intermediate objects and the bottom to see things close-up.
  • This may be especially useful to people who wear single-vision eyeglasses for distance (due to Myopia) in addition to reading glasses for near work (due to presbyopia).

Types of lenses:

Source: TH

At least 100 million in India need spectacles but have no access Science and tech

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