Which of the following statements is correct?

Options

A. Cornea consists of dense matrix of collagen and is the most sensitive portion of the eye.
B. Cornea is an external, transparent and protective proteinaceous covering of the eyeball.
C. Cornea consists of dense connective tissue of elastin and can repair itself.
D. Cornea is convex, transparent layer, which is highly vascularized.

Answer

To determine which statement about the cornea is correct, let's analyze each statement step by step:

1. **First Statement**: "Cornea consists of dense matrix of collagen and it is the most sensitive portion of eye."
- The cornea is indeed made up of a dense matrix of collagen fibers, which provide structure and strength. Additionally, the cornea is known to be highly sensitive due to the presence of numerous nerve endings. This statement is correct.

2. **Second Statement**: "Cornea is an external transparent protective proteinaceous covering of the eyeball or cornea consists of dense connective tissue of elastin and can repair itself."
- While the cornea is a transparent protective covering of the eyeball, it is primarily composed of collagen, not elastin. The ability of the cornea to repair itself is true, but the statement is misleading due to the mention of elastin. Therefore, this statement is incorrect.

3. **Third Statement**: "Cornea is convex transparent layer which is highly vascularized."
- The cornea is indeed a transparent layer, but it is not highly vascularized. In fact, the cornea is avascular (lacking blood vessels) to maintain its transparency. This statement is incorrect.

4. **Fourth Statement**: This statement appears to be a repetition of the previous ones and is also incorrect based on the same reasoning.

Based on the analysis, the first statement is the only correct statement regarding the cornea.

### Final Answer:
The correct statement is: "Cornea consists of dense matrix of collagen and it is the most sensitive portion of eye."