Which of the following is a characteristic feature of the human cornea ?

Options

A. It is secreted by the conjunction and glandular cells.
B. It is also called a lacrimal gland , which secretes tears.
C. Blood circulation is absent in the cornea
D. In old age, the cornea hardens and a white layer is deposited over it which leads to the formation of a cataract.

Answer

To solve the question regarding the characteristic feature of the human cornea, we will analyze each of the provided options step by step.

### Step 1: Understand the Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. It plays a crucial role in focusing vision.

### Step 2: Evaluate the Options
1. **Option 1: Secreted by the conjunctiva and glandular cells**
- This option is incorrect. The cornea is not secreted by the conjunctiva; rather, it is a distinct structure of the eye.

2. **Option 2: Lacrimal gland secretes tears**
- This option is also incorrect. While the lacrimal gland does secrete tears, it is not a characteristic feature of the cornea itself.

3. **Option 3: Blood circulation is absent in the cornea**
- This option is correct. The cornea does not have blood vessels; it receives nutrients and oxygen directly from the air and the aqueous humor. This absence of blood circulation reduces the risk of rejection during corneal transplantation.

4. **Option 4: In old age, the cornea hardens and a white layer is deposited over it, leading to cataract formation**
- This option is misleading. While cataracts do affect vision, they are primarily related to the lens of the eye, not the cornea itself.

### Step 3: Conclusion
Based on the evaluation of the options, the correct answer is **Option 3: Blood circulation is absent in the cornea**.