Question

A person uses spectacles (lens) of +2D power. His defect of vision is.

• A. Myopia
• B. Hypermetropia
• C. Presbyopia
• D. Astigmatism

Hint:

A positive power lens (convex) is used to correct hypermetropia (farsightedness), while myopia is corrected with a negative power lens (concave).

Answer 1

The Correct Option is B

Step 1: Understanding the power of a lens.
The power \( P \) of a lens is given by the formula: \[ P = \frac{1}{f} \, (\text{in meters}) \] where \( f \) is the focal length of the lens. A positive lens (convex lens) is used to correct hypermetropia (farsightedness), where the image focuses behind the retina, requiring a converging lens to bring the focus to the retina.
Step 2: Identifying the defect.
- (A) Myopia: Myopia (nearsightedness) is corrected with a diverging (concave) lens, not a convex lens.
- (B) Hypermetropia: Hypermetropia is corrected with a positive (convex) lens, as the person cannot focus on nearby objects.
- (C) Presbyopia: Presbyopia is a condition related to aging, where the eye loses the ability to focus on nearby objects, often requiring reading glasses.
- (D) Astigmatism: Astigmatism requires cylindrical lenses to correct the distortion of images caused by the uneven curvature of the eye's surface.
Conclusion: The defect is hypermetropia, corrected with a +2D convex lens.