Correct Option
The correct option is (b).
Explanation
The human eye functions as a natural optical instrument where a crystalline lens focuses light onto the retina. A cataract is a common ocular defect characterized by the opacification (clouding) of this natural lens, leading to vision impairment.
Statement-wise Analysis
- Statement 1 is Incorrect. Cataracts do not occur exclusively in children. While congenital cataracts (present at birth) do exist, the condition is predominantly associated with aging (senile cataract). It is most common in elderly individuals due to the denaturation of lens proteins over time.
- Statement 2 is Correct. The primary physiological change in a cataract is the crystalline lens becoming milky or cloudy. This opacity obstructs or scatters the passage of light, preventing a clear image from forming on the retina, which results in blurred vision or partial blindness.
- Statement 3 is Incorrect. Cataracts can be treated effectively. The standard treatment involves a surgical procedure where the opaque natural lens is removed and replaced with an artificial Intraocular Lens (IOL) to restore clear vision.
Key Takeaway: A cataract is the clouding of the eye's crystalline lens, primarily caused by aging, and is treatable through surgical replacement of the lens.