Which type of lens is used to correct astigmatisum ?

Explanation

### Step-by-Step Solution

1. **Understanding Astigmatism**:
- Astigmatism is a common vision condition that occurs when the cornea or lens of the eye is curved more steeply in one direction than in another. This irregular shape prevents light from focusing properly on the retina, leading to blurred or distorted vision.

2. **Identifying the Corrective Lens**:
- To correct astigmatism, specific types of lenses are required. The lens must compensate for the uneven curvature of the cornea or lens in the eye.

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