Question

When do we say that a particular person is suffering from hypermetropia? List two causes of this defect. Name the type of lens used to correct this defect.

Answer 1

Step 1: Understanding Hypermetropia:
Hypermetropia, or farsightedness, is an eye condition where individuals can see distant objects clearly but struggle to focus on nearby objects. This occurs because the image of a near object is projected behind the retina instead of directly on it.

Step 2: Causes of Hypermetropia:
1. Shortened Eyeball:
A shortened eyeball, specifically in its front-to-back dimension, causes light entering the eye to converge behind the retina.

2. Weak Lens or Cornea:
Insufficient curvature or weakness of the eye's lens or cornea can prevent proper focusing of light onto the retina.

Step 3: Correcting Hypermetropia:
Hypermetropia is corrected using convex lenses, also known as converging lenses. These lenses increase the convergence of light rays before they enter the eye, ensuring they focus correctly on the retina.

Step 4: Conclusion:
- Hypermetropia results in clear distant vision but blurry near vision, as images focus behind the retina.
- Contributing factors include a shortened eyeball or inadequate lens/corneal power.
- Convex lenses are employed to rectify this condition by focusing light accurately on the retina.