Water content In lens is –
**Core Concept**
The lens of the eye is a transparent structure behind the iris, responsible for focusing light on the retina. Its water content plays a crucial role in maintaining its transparency and refractive power. The lens's water content is tightly regulated by various mechanisms to ensure proper vision.
**Why the Correct Answer is Right**
The lens's water content is approximately 65-70%. This high water content is necessary to maintain its refractive index and transparency. The lens's water content is primarily composed of a high concentration of crystallins, which are proteins that provide structural support and maintain the lens's transparency. The water content of the lens is also regulated by the lens's unique metabolic properties, including the presence of the enzyme aldose reductase, which helps to maintain the lens's water balance.
**Why Each Wrong Option is Incorrect**
**Option A:** 0% is incorrect because the lens would be completely opaque and unable to focus light without any water content.
**Option B:** 30% is incorrect because this water content would result in a lens that is too dense and unable to focus light properly.
**Option C:** 90% is incorrect because this water content would result in a lens that is too hydrated and unable to maintain its structural integrity.
**Clinical Pearl / High-Yield Fact**
The lens's water content is tightly regulated to maintain its transparency and refractive power. This is why conditions such as cataracts, which involve the accumulation of water and proteins in the lens, can cause vision loss.
**Correct Answer: C. 70%**