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S4B4: Surgery > Ocular Anatomy & Clinical Correlation > Flashcards

Ocular Anatomy & Clinical Correlation Flashcards

1
Q

What are the two major pathologies we see in the lens?

A
  1. Presbyopia
    1. lose ability change the shape of the lens to allow for accomodation as we age
  2. Cataract
    1. cloudy as we age
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2
Q

The cornea is composed of what cell types?

Its stroma is composed of what types of collagen?

A

epithelium, stroma, endothelium

stroma: type I, IV, V collagen

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3
Q

What two structures are responsible for focusing light?

Relative percentages of each?

A

Cornea: 70%

Crystalline lens: 30%

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4
Q

What muscle is the main focusing muscle of the eye?

It is attached to what structes to accomplish this?

A

ciliary body

attached to & suspends the crystalline lens via zonules

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5
Q

What structure separates the anterior & posterior chambers?

A

crystalline lens

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6
Q

What structure has the highest concntration of protein in the body?

A

lens

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7
Q

The lens gets most of its energy through what process?

A

glycolysis

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8
Q

The “uvea” references what structures?

describe these components

A
  • iris
    • thin, colored portion
    • helps to control size of pupil
  • ciliary body
    • main focusing muscle of the eye
    • produces aqueous humor tha tbathes anterior chamber
  • choroid
    • deep to retina, highly vascular & provides most of the blood fow adn suport to retinal tissue
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9
Q

Where is the aqueous humor that bathes the anterior chamber produced?

A

ciliary body

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10
Q

What are the components of the vitrous?

It accounts for what percent of total eye volume?

A

sticky, jelly-like: type II collagen, hyaluronic acid, water

80%

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11
Q

What are the two major pathologies we see with the vitreous?

A
  1. Vitreous detachment
    1. Liquification as we age - leads to it separating from retina (50-60 yr)
  2. Retinal tears
    1. can potentially become retinal detachment during separation
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12
Q

What is it called where the conjunctive, cornea & sclera all meet?

A

limbus

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13
Q

What is the presentation of a patient with nasolacrimal duct obstruction?

Treatment?

A
  • Presentation
    • recurrent tearing and discharge in an infant
  • Treatment
    • warm digital massage over nasolacrimal sac
    • typically resolves by 12 months - if not, opthalmologist can probe to open
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14
Q

What is the term for the fibrous layer beginning at the periosteum of the skull & extending to the eyelids?

A

orbital septum

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15
Q

What are the terms for an infection anterior to the orbital septum & posterior to the orbital septum?

A
  • anterior - periorbital cellulitis
  • posterior - orbital cellulitis
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16
Q

Presentation of a patient with periorbital cellulitis?

Treatment?

A
  • Mild condition - common
    • NO proptosis
    • NO ophthalmoplegia
    • LESS pain with eye movement
    • NO vision loss
  • Treatment
    • antibiotics
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17
Q

Presentation of a patient with orbital cellulitis?

Treatment?

A
  • Presentation - SERIOUS
    • ophthalmoplegia
    • pain with eye movement
    • proptosis
    • chemosis of conjunctiva
    • coexistin rhinosiusitis (90%)
  • Treatment
    • IV antibiotics x3weeks
    • frequently inpatient
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18
Q

What is the common cause of orbital cellulitis?

What complications can arise from orbital cellulitis?

A
  • Cause
    • spread from adjacent siunses (usually ethmoid)
  • Complications
    • cavernous sinus thrombosis
    • meningitis
    • cerebral, orbital, subperiosteal abscess
    • vision loss
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19
Q

Identify the bones & indicated landmarks on the provided image

A
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20
Q

What bones make up the orbital roof?

A

frontal bone

lesser wing of the sphenoid

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21
Q

What bones make up the lateral wall of the orbit?

A

zygogatic bone

greater wing of the sphenoid

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22
Q

What is the thickest & strongest parts of the orbit?

A

lateral wall

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23
Q

What bones make up the orbital floor?

A

maxillary

palatine

zygomatic

24
Q

What vessels are transmitted in the infraorbital groove?

A

infraorbital artery

maxillary dividiosn of trigeminal nerve

25
Q

What vessels are transmitted in the supraorbital notch?

A

supraorbital vessels & frontal nerve

26
Q

What bones make up the medial wall of the orbit?

A

ethmoid

lacrimal

maxillary

sphenoid

27
Q

What is the thinnest wall of the orbit?

What is its special name?

A

medial wall

overlying the ethmoid sinus = lamina papyracea

28
Q

What is a “trap-door” fracture & where does this most often occur?

A

when bone breaks & then snaps back, trapping vessels/muscles that can become ischemic

most commonly happens in younger patients b/c have more flexible bones - orbital floor

29
Q

What is the clinical presentation of a patient with an orbital fracture?

A
  • trauma history with pain
  • facial asymmetry
  • enophthalmos
  • edema/exophthalmos
  • diplopia
30
Q

What steps should you take if you have a patient who has experienced blunt trauma & you suspect orbital fracture?

A
  • physical exam
    • palpate orbital rim
    • pupillary response (CN II compression from edema)
    • visual acuitty
    • infraorbital nerve anesthesia
      • CN V2 maxially nerve division
  • CT Face & Orbit with contrast
  • refer to ophthalmologist ASAP
31
Q

What structures are located in the superior orbital fissure?

A

CN III, CN IV, CN V1, CN VI

ophthalamic vein

sympathetic fibers

32
Q

What structures are located in the inferior orbital fissure?

A

CN V2, inferior opthalamic vein

33
Q

What structures are located in the optic canal?

A

CN II, Ophthalamic artery, central retinal vein

34
Q

What artery supplies the majority of the eye itself?

What about the eyelids & conjunctiva?

A
  • Eye itself - internal carotid
  • Eyelid & Conjunctiva - external carotid
35
Q

CN III controlls what ocular muscles?

A

all rectus (except lateral rectus)

eyelid

36
Q

CN IV controls what ocular muscles?

A

superior oblique

37
Q

CN VI controls what ocular muscles?

A

lateral rectus

38
Q

Fill out the provided table indicating what motion is the result of what nerve/muscle.

A
39
Q

Having the patient move their eyes in these directions is assessing which muscles?

A
40
Q

The provided image is an example of what nerve palsy?

This is most likely due to what type of disease?

A

CN III palsy

d/t decreased diffusion of oxygen & nutrients to interior fibers

(DM / HTN)

41
Q

The autonomic nerve fibers in CN III innervate what reflex?

They are most commonly affected by what?

A

pupillary response

on periphery of nerve - first affected by compression

posterior communicatign artery aneurysm or superior cerebellar artery aneurysm

uncal herniation

intracranial neoplasm

42
Q

What is the next step in management if you have a patient with a blown/dilated pupil?

A

CT / MRA

it could be life threatening if it is a posterior communicating artery aneurysm

43
Q

The patient in the provided image has what nerve palsy?

A

CN VI

44
Q

What nerve is responsible for closing the eye?

A

CN VII

45
Q

Sympathetic fibers reach the eye via what nerve?

What about parasympthetics?

The each have what effect on pupil size?

A
  • sympathetic- nasociliary (branch of opthalamic nerve)
    • mydriasis (dilation)
  • parasympathetic- CN III
    • miosis (constriction)
46
Q

What are the sensory nerves to the eye?

A

CN V

V1 opthalamic & V2 Maxillary

47
Q

Describe the nuclei & muscles involved in conjugate gaze

A

when looking left

left nucleus CN IV contracts the left lateral rectus & stimulates the right nucleus of CN III (via right MLF) to contract the right medial rectus

48
Q

Internuclear ophthalmoplegia that interrupts conjugate gaze is named for which eye?

A

the eye that is paralyzed

49
Q

If there is a lesion in the right MLF, what is the result?

A

right eye cannot abduct

right INO

50
Q

What is the difference in presentation from a CN VII lower motor neuron lestion & an upper motor neuron lesion?

A
  • lower - whole ipsilateral side is affected
  • upper - contralateral face below eye is affected
51
Q

What is the most important eye consideration when dealing with a patient who has a CN VII palsy?

A

eye lubricants

52
Q

What visual field defect would result from a lesion at 3 or 6?

A
53
Q

Horner syndrome is associated with what conditions?

A

pancoast tumor (in apex of lung)

spinal cord lesion above T1 (Brown-Sequard Syndrome)

Late stage syingomyelia

54
Q

What is the pneumonic for Horner Syndrome?

A

sympthetic denervation of face due to ipsilateral sympathetic trunk damage

PAM is horny

  • P - ptosis
  • A - anhidrosis (absense of sweating & flusing)
  • M - miosis (pupil constriction)
55
Q

If you have a pupillary light reflex defect, you probably have problems with what structures?

Common causes?

A

optic nerve or retina

Cause - optic neuritis in MS, acute inflammation demyelination of CNS

56
Q
A

S4B4: Surgery (4 decks)

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