Which kind of lens can correct the defective vision in the given figure?

Defective vision

Corrective lens

The correct answer is Lens type d.

Key Points

• A concave lens (Lens type d) is used to correct myopia (nearsightedness).
• Myopia occurs when the eye is too long or the cornea is too curved, causing light rays to focus in front of the retina.
• A concave lens diverges light rays before they enter the eye, allowing them to focus directly on the retina.
• Concave lenses are thinner at the center and thicker at the edges.
• This type of lens is prescribed based on the degree of myopia, measured in diopters.

Additional Information

• Hyperopia (Farsightedness)
  • Occurs when the eye is too short or the cornea has too little curvature.
  • Light rays focus behind the retina, making nearby objects appear blurry.
  • A convex lens is used to correct hyperopia by converging light rays before they enter the eye.
• Astigmatism
  • Caused by an irregular curvature of the cornea or lens.
  • Leads to distorted or blurred vision at all distances.
  • Cylindrical lenses are used to correct astigmatism, specifically tailored to the irregular curvature.
• Presbyopia
  • Age-related condition where the eye's lens loses elasticity.
  • Difficulty in focusing on close objects, common in people over 40.
  • Corrected with bifocal or progressive lenses.