Astigmatism occurs when the cornea does not have a truly spherical shape. This defect can be cured by the use of a

Options

A. concave lens
B. cylindrical lens
C. convex lens
D. plano-convex lens

Explanation

### Step-by-Step Solution:

1. **Understanding Astigmatism**:
- Astigmatism is a visual defect that occurs when the cornea (the front part of the eye) is not perfectly spherical. This irregular shape causes light rays to focus at different points on the retina, leading to blurred or distorted vision.

2. **Identifying the Problem**:
- The irregular shape of the cornea means that it cannot focus light correctly, which results in unclear images. This is why individuals with astigmatism often experience blurred vision.

3. **Exploring Correction Methods**:
- To correct astigmatism, we need a lens that can compensate for the uneven curvature of the cornea. Regular spherical lenses cannot correct this issue effectively.

4. **Choosing the Right Lens**:
- The appropriate solution for astigmatism is the use of a **cylindrical lens**. Unlike spherical lenses, cylindrical lenses have different curvatures in different orientations, allowing them to focus light more accurately for individuals with astigmatism.

5. **Conclusion**:
- Therefore, the defect of astigmatism can be cured by the use of a **cylindrical lens**.

### Final Answer:
Astigmatism can be cured by the use of a **cylindrical lens**.

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