Eye

Question 1

State how the eye focuses on distant objects

Answer 1

Ciliary muscles relax, pulling on the suspensory ligaments. Suspensory ligaments become taut, pulling on the edge of the lens. The lens becomes thinner and less convex, increasing its focal length. Light rays from the distant object are sharply focused on the fovea of the retina.

Question 2

State how the eye focuses on near objects

Answer 2

Ciliary muscles contract, relaxing their pull on the suspensory ligaments. Suspensory ligaments slacken, relaxing their pull on the lens. The lens, being elastic, becomes thicker and more convex, decreasing its focal length. Light rays from the near object are sharply focused on the retina.

Question 3

Describe eye in bright light

Answer 3

The circular muscles of the iris contract. The radial muscles of the iris relax. The pupil becomes smaller or constricts. This reduces the amount of light entering the eye.

Question 4

Describe eye in dim light

Answer 4

The radial muscles of the iris contract. The circular muscles of the iris relax. The pupil becomes dilates. This increases the amount of light entering the eye.

Question 5

Define pupil reflex and state its function

Answer 5

The pupil reflex controls the amount of light entering the ye so that excessive light would not enter the eye to damage the photoreceptors of the retina under bright conditions.