eye

• What part of the eye refracts light first?

Cornea

• What part controls light entering the pupil?

Iris

• What structure focuses light onto the retina?

Lens

• What is the light-sensitive layer of the eye?

Retina

• Which cells detect dim light but no colour?

Rods

• Which cells detect different colours in bright light?

Cones

• What carries electrical impulses to the brain?

Optic nerve

• What do ciliary muscles do for distant objects?

Relax

• What do suspensory ligaments do for distant objects?

Pull tight

• What shape does the lens take for distant objects?

Less rounded

• What do ciliary muscles do for close objects?

Contract

• What do suspensory ligaments do for close objects?

Slacken

• What shape does the lens take for close objects?

More rounded

• What objects can long-sighted people not focus on?

Near objects

• Where is light focused in long-sightedness?

Behind the retina

• What type of lens corrects long-sightedness?

Convex lens

• What objects can short-sighted people not focus on?

Distant objects

• Where is light focused in short-sightedness?

In front of retina

• What type of lens corrects short-sightedness?

Concave lens

• What causes red-green colour blindness?

Faulty cones

• What is a cloudy patch on the lens called?

Cataract

• How are cataracts treated?

Replacing the lens