How Eyes Work Flashcards

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1
Q

What is a far point?

A

A far point is the most distant point an eye can focus on. For a normal eye this is infinite. The lens is at is thinnest when looking at vet distant objects like the moon.

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2
Q

What is the near point?

A

The near point for a normal eye is the closest point on which an eye can focus. This is about 25cm for adults with normal vision

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3
Q

What is the pupil

A

The round hole in the centre of the eye. It can change its simple in response to changes in light levels

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4
Q

How does the eye focus an image that is far away

A

The ciliary muscles relax making the ring of muscles wide and so the lens is pulled into a thin shape

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5
Q

What is the iris

A

Coloured ring that controls the size of the pupil and so controls how much light enters the eye

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6
Q

What’s the cornea

A

Outer transparent layer of the eye that refracts light entering the eye

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7
Q

What’s the retina

A

Tissue at the back of the eye that contains light receptors.

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8
Q

What’s the lens

A

Further converges light rays (which have been refracted by the cornea) to focus them on the retina

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9
Q

What happens when light reaches the retina

A

The image formed is converted into electrical impulses by cells in the retina and neurones carry impulses (along the optic nerve) to the brain which interprets them

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10
Q

How does the eye focus an image that is near

A

The ciliary muscles contract making the ring of muscles smaller and so the lens relaxes into a fatter shape

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