Astigmatism for a human eye can be removed by using

Options

A. concave lens
B. convex lens
C. cylindrical lens
D. prismatic lens

Explanation

To solve the question regarding how to remove astigmatism in the human eye, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Astigmatism**:
- Astigmatism is a common vision condition caused by an irregular shape of the cornea or lens. This irregularity prevents light from focusing properly on the retina, leading to blurred or distorted vision.

2. **Identify the Cause**:
- In astigmatism, the cornea is not uniformly curved. This means that light rays entering the eye do not converge at a single point, causing difficulty in seeing objects clearly in different orientations.

3. **Consider Lens Options**:
- The question provides four options for correcting astigmatism: concave lens, convex lens, cylindrical lens, and prismatic lens.
- **Concave Lens**: Used for myopia (nearsightedness).
- **Convex Lens**: Used for hyperopia (farsightedness).
- **Cylindrical Lens**: Specifically designed to correct astigmatism by compensating for the uneven curvature of the cornea.
- **Prismatic Lens**: Used to correct double vision or misalignment of the eyes.

4. **Determine the Correct Lens**:
- Since astigmatism is due to the uneven curvature of the cornea, the cylindrical lens is the most appropriate choice. It has different optical power in different orientations, which allows it to correct the specific distortion caused by astigmatism.

5. **Conclusion**:
- Therefore, astigmatism for a human eye can be effectively removed by using a **cylindrical lens**.

### Final Answer:
Astigmatism for a human eye can be removed by using **cylindrical lens**.

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