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Y2 Neurology > Vision 1 > Flashcards

Vision 1 Flashcards

1
Q

define -

light rays bend to form a sharp image on the retina?

A

refraction

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2
Q

define -

changing the shape of the len by the ciliary body to focus on far away/near objects by refraction?

A

accommodation

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3
Q

what three mechanisms are involved in accommodation ?

A
  • changing lens shape
  • pupils constrict
  • eyes converge
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4
Q

how does the lens thicken?

A
  1. ciliary body contracts making the ciliary body bulge
  2. space in the middle decreases
  3. suspensory ligaments become
  4. lens is no longer under stretch so lens becomes thicker
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5
Q

what shape does the lens become when it is relaxed?

A

more spherical

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6
Q

when do the pupil constrict ?

A

when we are looking at an object up close and need to sharp focus

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7
Q

what muscle is used to constrict the pupils ?

A

pupillary constrictor

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8
Q

what autonomic response constricts pupils

A

parasympathetic response

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9
Q

what cranial nerve constricts the pupil?

A

occulomotor nerve

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10
Q

what extrinsic eye muscles are responsible for converging the eyes?

A

medial rectus

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11
Q

what muscles tend to be thicker

  • medial recti
  • lateral recti
A

medial rectus

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12
Q

what is myopia?

A

short sightedness

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13
Q

what is hyperopia ?

A

long sightedness

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14
Q

what is astigmatism ?

A

non-spherical curvature of cornea

- increased curvature

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15
Q

what is presbyopia ?

A

long sightedness of old age

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16
Q

what is emmetropia?

A

perfect vision

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17
Q

what is the most common cause of myopia?

A

eye ball is too long

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18
Q

in myopia,

is the image focused infront or behind the retina?

A

in front

19
Q

myopia

- do close things look clear or hazy?

A

clear

20
Q

what are the common symptoms of myopia in toddlers?

A

loss of interest in sports/people. More interest in books, pictures.

21
Q

what are the common symptoms of myopia in infants ?

A

divergent squint

22
Q

what type of lens is used in glasses to correct myopia ?

A

biconcave to decrease the power of bending

23
Q

can laser eye surgery be used to treat myopia?

A

yes

24
Q

in hyperopia do close objects look hazy or clear?

A

hazy

25
Q

what are the anatomical differences in hyperopia?

A

eye ball is too short and lens is too flat

26
Q

in hyperopia, what kind of squint would a child have?

A

convergent

27
Q

why does children with hyperopia have to be treated immediately ?

A

to prevent a lazy eye

28
Q

where does the image focus during astigmatism?

A

the image is focused in two locations which causes double vision

29
Q

during astigmatism do close and distant objects appear clear or blurry?

A

distant and close objects appear hazy

30
Q

what type of glasses are used to correct astigmatism?

A

cylindrical glasses

31
Q

what is the cause of presbyopia?

A

the lens becomes less mobile with old age

32
Q

what type of glasses are used to correct presbyopia?

A

biconvex

33
Q

what is phototransduction ?

A

The energy in light waves need to stimulate photoreceptor cells on the retina
conversion of light energy to electrical energy by rods and cones

34
Q

what is the shape of the outer segment of the

  • rod
  • cones
A

rod
- rod shaped outer segment

cones
- cone shaped outer segment

35
Q

is a thin or thick lens more powerful?

A

thick

36
Q

name the two photoreceptors in the eye

A

rods

cones

37
Q

How does bleaching of the visual pigment result in phototransduction?

A

Phototransduction cascade.

38
Q

What role does Vitamin A play in the visual pigment?

A

visual pigment regeneration

39
Q

what channel closes as a result of the phototransduction casade ?

A

Na channels

40
Q

what are three symptoms which can be caused by vitamin A deficiency ?

A
  • night blindness

- abnormal conjunctiva and corneal epithelium

41
Q

is Vit A water or fat soluble?

A

fat soluble

42
Q

what are two clinical signs of a Vitamin A deficiency ?

A

Bitots spots on conjunctiva

corneal ulceration

43
Q

describe the basic mechanism of a photon landing on a photoreceptor

A
  1. photon lands on Rhodopsin
  2. 11-cis isomer changes to all-trans isomer
  3. this results in bleaching of a visual purple colour
  4. Na channels close
  5. results in hyper polarisation of the cell
  6. Hyperpolarisation increases Ca ions which stimulates the retinal cells

Y2 Neurology (52 decks)

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