Anatomy of the Visual System

What is the function of the visual cortex in the visual system?

Which part of the eye accounts for most of the focusing of light?

Which element of the eye is responsible for adaptive changes between bright and dim lighting conditions?

What is the index of refraction for the lens center?

What consequence results from the malfunction of any part of the visual system?

Which of the following parts of the eye has the lowest index of refraction?

What aspect of the cornea is mainly responsible for defective vision?

Which focusing component of the eye is variable in shape?

The sense of vision consists of three major components: the eyes, the system of nerves, and the visual cortex.
Blindness results if any one of these parts does not function.

The cornea is a fixed focus element that does about two-thirds of focusing light.
The lens is variable in shape and has the ability to focus objects at various distances.

The cornea focuses by bending (refracting) light rays.
The amount of bending depends on the curvatures of its surfaces and the speed of light in the lens compared with that in the surrounding material.

The iris is the colored part of the front of the eye.
Functions of the iris:
- Adapts vision from light to dark and vice versa.
- Aids the eye by increasing or decreasing incident light on the retina until the retina adapts to new lighting conditions.
- Reduces lens defects under bright light conditions.