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neuro.psych.optho > optho anatomy > Flashcards

optho anatomy Flashcards

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1
Q

what are the 3 layers of the eye?

A

1) innermost retinal layer: nueral retina + retinal pigment epithelium
2) choroid layer: middle vascular layer, contains choroid, iris, ciliary body
3) corneoscleral layer: outer fibrous layer contains sclera and cornea

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2
Q

What are the 3 chambers of the eye?

A

1) anterior chamber: cornea, iris, lens; aqueous humor
2) posterior chamber: iris, lens, zonule fibers, ciliary body; aqueous humor
3) vitreous humor: lens, zonule fibers, retina; gelatinous vitreous humor

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3
Q

the retina develops from what structure?

A

primitive diencephalon–>optic vesicle–>optic cup

  • inner layer optic cup: neural retina
  • outer layer of optic cup: retinal pigment epithelium
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4
Q

what primitive layer does the cornea develop from?

A

ectoderm

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5
Q

retinal pigment epithelium

A

nutritional support for photoreceptors; absorbs stray light; phagocytoses shed membrane material from outer segments of photoreceptors

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6
Q

photoreceptors

A

carry out phototransduction to convert light into neural activity

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7
Q

interneurons of retina

A

process signals from photoreceptors

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8
Q

ganglion cells of retina

A

transmit signals from interneurons to the brain via the optic nerve

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9
Q

fovea/macula

A

contains all cones, no blood vessels and cell spreading to form a pit
-maximize high acuity color vision

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10
Q

optic disk/optic papilla

A

origination of optic nerve; no photoreceptors=functional blind spot

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11
Q

ora serrata

A

multilayered neural retina simplifies into single layer columnar epithelium that is not photoreceptive

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12
Q

choroid

A

highly vascularized, pigmented loss CT layer

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13
Q

ciliary body

A

regulates fine focus by adjusting shape of lens
contains ciliary muscle (smooth muscle) with parasympathetic innervation
zonule fibers connect ciliary body to lens

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14
Q

what is the source of aqueous humor?

A

ciliary processes

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15
Q

Iris

A

adjusts the amount of light entering the eye by changing the size of the pupils

  • contains 2 sets of muscles:
    1) dilator pupillae (myoepithelial cells): sympathetic innervation; dilate pupil
    2) constrictor pupillae (smooth muscle): parasympathetic innervation, constrict pupil
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16
Q

sclera

A

covers posterior 5/6 of eye
dense opaque connective tissue
point of insertion of extraocular muscles

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17
Q

cornea

A
  • covers anterior 1/6 of eye
  • transparent, avascular
  • major refractive element of the eye w/ 5 layers
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18
Q

limbus

A

point of transition from sclera to cornea

  • location of canal of schlemm which drains aqueous humor
  • if drainage is blocked–>glaucoma
19
Q

opacification of lens

A

cataracts

20
Q

conjunctiva

A

lines inner surface of eyelid

-composed of stratified columnar epithelium with goblet cells

21
Q

lacrimal gland

A
  • tubuloalveolar serous gland that secretes tears; large lumens and few ducts
  • looks like pancreas w/o islets
22
Q

myopia

A
  • light rays from distant objects are focused in front of the retina
  • causes: eyeball is too long, refraction is too strong
  • presents as blurred distance vision, near vision is usually good
  • tx: concave lens, refractive surgery
23
Q

hyperopia

A
  • Light rays from distant objects are focused behind retina
  • Overcome in early life by great ability for accommodation
  • Vision problems start occurring as accommodation weakens

Causes:
• Eyeball is too short
• Refraction is too weak

clinical:
• Presents later in life
• Youth: no symptoms (accommodation)
• Adulthood: blurred near +/- distance vision

tx:
• Convex lens (+)
• Refractive surgery

24
Q

astigmatism

A

-light rays are not refracted uniformly–>multiple points of focus
Causes: non-spherical cornea (egg shaped), non-spherical lens
-clinical: blurry vision
-tx: cylindrical lens, refractive surgery

25
Q

presbyopia

A

part of normal aging process

  • decreased accomodative ability–>cant bring near objects into focus
  • patients hold reading material far away
  • tx: convex lens
26
Q

aphakia

A

Absence of the lens, which results in the eye being short 20 diopters of refracting power
-can be corrected by things that offer convex power: thick glasses, contact lens, lens implant

27
Q

esotropia

A

eye turned in

28
Q

exotropia

A

eye turned out

29
Q

hypertropia

A

one eye higher than the other

30
Q

hypotropia

A

one eye lower than the other

31
Q

strabismus

A

misalignment of the visual axes of the eyes due to the eyes not working together

32
Q

comitant strabismus

A
  • deviation is consistent regardless of gaze
  • NO known neuromuscular etiology
  • Common in children
33
Q

incomitant strabismus

A
  • Deviation size increases when the gaze is in the direction of the involved muscle
  • Causes include CN palsy, thyroid eye disease, MG and mechanical obstruction
  • Less common than comitant strabismus
34
Q

congential esotropia

A
  • comitant strabismus
  • Seen in infants in the first few months of life
  • Amblyopia is common
  • Treatment is surgery
35
Q

accommodative esotropia

A
  • comitant strabismus
  • Develops between ages 1-4
  • Occurs in children who are very hyperopic (farsighted)
  • Intermittent at first, but increases over time
  • Amblyopia is common
  • Excess accommodation → excess convergence (esotropia)
  • Treatment is glasses (reduces excess accommodation)
  • Many children can wean off of glasses by teenage years
  • Outcome is extremely good
36
Q

sensory esotropia or exotropia

A
  • comitant strabismus
  • Occurs in eye with poor vision
  • Treatment is with surgery
  • Surgery straightens eye, but does NOT improve vision
  • Surgery often needs to be repeated within 15 years
37
Q

idiopathic exotropia

A
  • comitant strabismus
  • Begins intermittently, but increases in frequency and duration
  • Usually more severe at distance
  • Amblyopia is common
  • Treatment is observation +/- eventual strabismus surgery
38
Q

CN 3 palsy

A
  • incomitant strabismus
  • Patient presents with ptosis, eye pointed down and out and dilated pupil
  • Levator muscle weakness → ptosis (droopy eyelid)
  • CN3-innervated EOM weakness → eye pointed “down and out”
  • Pupillary fibers weakness → dilated pupil
  • Mechanism may be congenital, trauma or aneurysm
  • Very difficult to treat, but some patients do well with surgery
39
Q

CN4 palsy

A
  • incomitant strabismus
  • Patient presents with vertical diplopia and a head-tilt away from bad side
  • Involves the superior oblique muscle
  • Mechanism may be congenital or trauma
  • Treatment for mild vertical diplopia is glasses with a prism
  • Treatment for severe vertical diplopia is surgery
40
Q

definition of amblyopia

A

impairment of vision without any detectable organic lesion of the eye

41
Q

causes of amblyopia

A
  • Refractive (49%): one eye has more far-sightedness, more near-sightedness or more astigmatism than the other eye (rarely, the cause may be bilateral abnormalities)
  • Strabismus (49%): alignment of the eyes such that the image does not fall on one (or both) of the maculas
  • Ocular Pathology (2%): cataract, glaucoma or corneal anomaly
42
Q

What do you correct before you correct strabismus?

A

amblyopia!

43
Q

development of amblyopia

A

o Until the age of 7, poor vision will result if a clear image is not focused onto the fovea of each eye
o This is a CNS problem, and will occur even if the eye is structurally completely normal
o The earlier the onset of amblyopia, the worse the prognosis

44
Q

when do you patch a child’s eye

A

before the age of 7!
-patch the strong eye to force the child to use the weaker eye and improve the amblyopia

  • Must be a sticky, bandaid-like patch
  • Amount of time patient needs to wear patch to improve vision is related to two things:
  • Degree of initial visual impairment
  • Age at time of first noticing amblyopia (the younger the age, the less patch time needed)
  • Once vision is improved, patient must continue to wear patch 1 hour per day until age 8-9

When patches absolutely do not work you can dilate the good eye with atropine

neuro.psych.optho (8 decks)

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