What is the nature of eye lens ? Is its focal length fixed ?

Explanation

### Step-by-Step Solution:

1. **Understanding the Nature of the Eye Lens**:
- The eye lens is responsible for focusing light onto the retina to form clear images.
- The nature of the eye lens is **convex** (or converging). This means it can converge light rays to a point, allowing for the formation of real images on the retina.

2. **Image Formation**:
- When light rays enter the eye, they pass through the convex lens (the eye lens) and converge to form an image on the retina.
...