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Neurology > Vision - Focus Transduction > Flashcards

Vision - Focus Transduction Flashcards

1
Q

How does an image form on the retina?

A

Light waves bend at the cornea and lens (refraction)

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2
Q

What happens to the lens when an object is moved closer?

A

More bending power needed so lens thickens

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3
Q

What is accommodation?

A

The change in focus from distant to close objects

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4
Q

What 3 things happen to allow the eye to obtain focused image?

A

Lens thickens
Pupil constricts
Eyes converge

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5
Q

What muscles are involved in thickening the lens?

A

Ciliary body contracts

Suspensory ligaments become lax

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6
Q

What muscle is involved in pupil constriction?

A

Pupillary constrictor (sphincter pupillae)

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7
Q

What muscle allows the eyes to converge?

A

Medial rectus

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8
Q

What is the name given to describe perfect vision?

A

Emmetropia

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9
Q

What is myopia?

A

Short sight

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10
Q

What is the most common cause of myopia?

A

Eyeball is too long

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11
Q

Where is the image formed in myopia?

A

In front of the retina

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12
Q

What are the symptoms of myopia?

A

Headaches
Divergent squint
Loss of interest in children

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13
Q

How is myopia corrected?

A

Biconcave lenses

Laser eye surgery

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14
Q

What is hyperopia?

A

Long sight

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15
Q

What is the most common cause of hyperopia?

A

Eyeball too short

Cornea and lens too flat

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16
Q

Where is the image found in hyperopia?

A

Behind the retina

17
Q

What are the symptoms of hyperopia?

A

Eyestrain

Convergent squint

18
Q

How is hyperopia corrected?

A

Biconvex lenses

Laser eye surgery

19
Q

What is an astigmatism?

A

Close and distant objects appear hazy

20
Q

What is the cause of an astigmatism?

A

Bending of light rays along one axis will never be the same as that of the other axis

21
Q

How is an astigmatism corrected?

A

Cylindrical glasses
Laser eye surgery
Toric lenses

22
Q

What is presbyopia?

A

Long sight in old age

23
Q

What is the cause of presbyopia?

A

Lens gets less mobile/elastic

Ciliary muscle not as capable of changing shape during contraction

24
Q

What is phototransduction?

A

Conversion of light energy to an electrochemical response by photoreceptors (rods and cones)

25
Q

What role does vitamin A play in the visual pigment?

A

Visual pigment regeneration

26
Q

What are the clinical signs of vitamin A deficiency?

A

Bitot’s spots in conjunctiva
Corneal ulceration
Corneal melting

Neurology (39 decks)

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