The correct option is (c) 2 and 3 only.
Explanation
The human eye functions as an optical system where a crystalline lens focuses light onto the retina. Common vision defects arise due to refractive errors (Myopia, Hypermetropia) or physiological changes in the transparency of the lens (Cataract).
Statement-wise Analysis
- Statement 1 is Incorrect. Near-sightedness, scientifically known as Myopia, is a defect where a person can see nearby objects clearly, but distant objects appear blurry. This occurs because the image of a distant object is formed in front of the retina rather than on it, often due to the elongation of the eyeball or excessive curvature of the eye lens.
- Statement 2 is Correct. Far-sightedness, scientifically known as Hypermetropia, is a defect where a person can see distant objects clearly, but cannot see nearby objects distinctly. This occurs because the image of a nearby object is formed behind the retina, often due to the eyeball being too short or the focal length of the lens being too large.
- Statement 3 is Correct. A Cataract is a condition where the crystalline lens of the eye becomes milky or cloudy, obstructing the passage of light and leading to vision loss. It is treated surgically by removing the opaque natural lens and replacing it with an artificial intraocular lens (IOL).
Key Takeaway
Myopia (Near-sightedness) impairs distant vision and is corrected using a concave lens. Hypermetropia (Far-sightedness) impairs near vision and is corrected using a convex lens.