Astigmatism can be corrected by using

Options

A. (a) Plain lens
B. (b) Convex lens
C. (c) Concave lens
D. (d) Cylindrical lens

Answer

**Step-by-Step Solution:**

1. **Understanding Astigmatism**: Astigmatism is a refractive error of the eye caused by an irregular shape of the cornea or lens. Instead of being perfectly round, the cornea has an uneven curvature, leading to distorted or blurry vision.

2. **Symptoms of Astigmatism**: Individuals with astigmatism may experience symptoms such as blurred vision, headaches, and eye strain. These symptoms can occur from birth or develop later in life.

3. **Types of Lenses**: To correct refractive errors, different types of lenses are used:
- **Plane Lenses**: These do not converge or diverge light and are not suitable for correcting astigmatism.
- **Convex Lenses**: These are used for hyperopia (farsightedness) and are not effective for astigmatism.
- **Concave Lenses**: These are used for myopia (nearsightedness) and are also not suitable for astigmatism.

4. **Corrective Lenses for Astigmatism**: The appropriate corrective lenses for astigmatism are cylindrical lenses, also known as toric lenses. These lenses have different curvatures in different meridians, allowing them to correct the specific irregular shape of the cornea.

5. **Conclusion**: Based on the above analysis, the correct answer to the question "Astigmatism can be corrected by using" is cylindrical lenses.

**Final Answer**: Astigmatism can be corrected by using cylindrical lenses (toric lenses).

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