Biology Chapter: The Eye Lens and Vision

Questions and Answers

What is the ability of the eye lens to adjust its focal length called?

Perception

Vision correction

Refraction

Accommodation (correct)

The focal length of the eye lens can be decreased to any length without limit.

False

What is the near point of the eye for a young adult with normal vision?

25 cm

When the ciliary muscles contract, the eye lens becomes ______.

thicker Signup and view all the answers

Match the following terms to their definitions:

Near Point = Farthest distance objects can be seen clearly Far Point = Closest distance objects can be seen distinctly Cataract = Condition causing partial loss of vision Accommodation = Adjustment of lens curvature for focusing Signup and view all the answers

What happens to the focal length of the eye lens when you look at distant objects?

It increases Signup and view all the answers

Cataract surgery can restore vision lost due to a cataract.

True Signup and view all the answers

What causes strain in the eye when reading printed material held too close?

Blurred image due to minimum focal length limit Signup and view all the answers

Study Notes

Eye Lens Structure and Function

The eye lens is made up of a fibrous, jelly-like material allowing flexibility.
Curvature of the lens can be adjusted by ciliary muscles, affecting focal length.

Accommodation Process

When ciliary muscles are relaxed, the lens becomes thinner, increasing focal length to see distant objects clearly.
When focusing on nearby objects, ciliary muscles contract, thickening the lens and decreasing focal length for clear vision.
This adjustment of the lens is known as accommodation.

Visual Distances

The minimum distance for clear vision without strain is approximately 25 cm, referred to as the near point or least distance of distinct vision.
For a normal eye, the far point is considered to be infinity, allowing clear vision for objects between 25 cm and infinity.

In elderly individuals, the crystalline lens may become milky and cloudy, a condition known as cataract.
Cataracts can lead to partial or total vision loss but are treatable through cataract surgery.

Description

This quiz explores the structure and function of the eye lens, focusing on its flexibility and the role of ciliary muscles in vision. Understand how the eye lens changes curvature to adjust focal length for seeing objects at varying distances.