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SYSTEMIC PATHOLOGY 3 > 1 – Orbit, Adnexa and Ocular Surface > Flashcards

1 – Orbit, Adnexa and Ocular Surface Flashcards

1
Q

Orbit

A
  • Cavity that encloses the eye
  • Protection and cushioning of globe
  • Conduit for vessels and nerves through multiple foramina
  • Attachment for extraocular muscles
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2
Q

How is the bony orbit formed?

A
  • By fusion of 5-7 bones depending on species
  • Incomplete: dog, cat, pig=lateral orbital ligament
  • Complete: horse, cow, sheep
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3
Q

What are the retrobulbar tissues?

A
  • Extraocular muscles
  • Nerves
  • Vessels
  • Fat
  • lacrimal gland
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4
Q

What are some periorbital structures?

A
  • Nasal and oral cavity
  • Paranasal sinuses
  • Tooth roots
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5
Q

What are the different changes in volume of the eye?

A
  • Exophthalamos
  • Enophthalamos
  • *see the third eyelid in both
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6
Q

What is exophthalmos?

A
  • Eye pushed formed
  • Space-occupying lesions
    o Retro bulbar OR orbital=same thing
  • Ex. neoplasia, inflammation, cysts
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7
Q

What is enophthalmos?

A
  • Eye sinks backward
  • Ex. dehydration, atrophy of orbital fat (older animals)
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8
Q

Eyelid ‘parts’

A
  • Outer lid surface: skin
  • Between: muscle and connective tissue
  • Inner lid: palpebral conjunctiva
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9
Q

What is at the eyelid margin?

A
  • Cilia
  • Tarsal/meibomian gland orifices
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10
Q

What is the function of the eyelid?

A
  • Sensation given by cilia
  • Meibomian gland secretions: lipid layer of tear film
  • Physical protection
  • Reduction of tear evaporation
  • Distribution of tears
  • Pumping of tears down the nasolacrimal duct
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11
Q

What are some things that can happen to eyelids? (bleph=eyelid)

A
  • Eyelid agenesis (coloboma)
  • Blepharitis (infectious or immune-mediated)
  • Eyelid laceration leading to fibrosis
  • Eyelid neoplasia
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12
Q

Bulbar conjunctiva

A
  • Conjunctival epithelium extending from limbus to conjunctival fornix
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13
Q

Palpebral conjunctiva

A
  • Conjunctival epithelium extending from eyelid margin to conjunctival fornix
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14
Q

What does conjunctiva do?

A
  • Smooth, lubricated surface for blinking
  • Conjunctival goblet cells: secrete mucin component of tears
  • Lymphoid follicles: respond to antigens as part of immune surveillance
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15
Q

What can happen to conjunctiva?

A
  • Conjuctiviitis
  • Follicular lymphoid hyperplasia
  • Goblet cell atrophy due to chronic conjunctivitis
    o Leads to tear film quality disorder
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16
Q

Conjuctivivits

A
  • Primarily in cats
  • Etiology: FHV-1, Chlamydophila felis
  • *non-specific and secondary in most other species
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17
Q

What are the 3 components of tears?

A
    1. Lipid layer: produced by meibomian glands of eyelid
    1. Aqueous layer: produced by lacrimal gland (60%) and third eyelid gland (40%) (quantitative)
    1. Mucin: produced by conjunctival goblet cells
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18
Q

What does lacrimal do?

A
  • Provide optically uniform corneal surface
  • Flush foreign material and debris
  • Permit passage of O2 and nutrients to the cornea
  • Antimicrobial enzymes
19
Q

Alterations of quantity (aqueous) or quality (mucin, oil) affect corneal health and clarity: examples

A
  • Vascularization
  • Keratinizaiton
  • Pigmentation
  • Lackluster cornea
  • Scarring
  • Corneal ulceration
20
Q

What is deficiency in quantity of lacrimal called?

A
  • Keratoconjuctivitis sicca
  • “dry eye”
21
Q

What is deficiency in quality of lacrimal called?

A
  • Tear film quality disorder
22
Q

Nasolacrimal system anatomy and physiology

A
  • Upper and lower puncta
  • 75% tear drain through it (25% evaporate)
23
Q

Nasolacrimal pathology (4 types)

A
  • Lacrimal punctal atresia: do NOT exist
  • Supernumerary puncta
  • Nasolacrimal cysts
  • Dacryocystitis
24
Q

Corneal anatomy

A
    1. Epithelium
    1. Stroma: collagen lamellae
    1. Descemet’s membrane: basement membrane of endothelium
    1. Endothelium: one layer of cells
25
Q

Corneal physiology

A
  • Refracts light
  • CLEAR for vision
    o Non-pigmented
    o Non-keratinized
    o Non-vascularized
    o Organized collagen lamellae
    o Dehydrated state
26
Q

Cornea is non-vascularized

A
  • Aqueous humor and tears provide nutrition and oxygen
27
Q

Dehydrated state of cornea

A
  • Active pumping in endothelium via Na/K ATPase
  • Physical barrier (tight junctions in endothelium and epithelium)
28
Q

Corneal pathology: loss of corneal clarity

A
  • Pigmentation
  • Keratinization
  • Vascularization
  • Edema
  • Cellular, lipid, mineral infiltrates
  • Corneal ulceration: superficial and deep
  • Scarring
29
Q

Superficial ulceration cornea

A
  • ONLY corneal epithelium
30
Q

Deep ulceration of cornea

A
  • Corneal stromal involvement
31
Q
A

corneal pigmentation

32
Q
A

Corneal edema

33
Q
A

Corneal mineral and lipid infiltration

34
Q

Corneal epithelial pathology

A
  • Epithelial hyperplasia, keratinization, pigmentation
    o *response to chronic inflammation
  • Superficial corneal ulceration
35
Q

What are the 3 mechanisms of corneal edema (corneal stromal pathology)?

A
  1. Disruption of epithelium: corneal ulcer
  2. Loss of endothelial pump function
  3. Leakage from newly formed vessels: corneal vascularization
36
Q

Loss of endothelial pump function (corneal edema)

A
  • Reduced number of endothelial cells (degeneration or dystrophy)
  • Reduced function of endothelial cells (inflammation, glaucoma
37
Q

Keratitis (ulcerative and non-ulcerative) (corneal stromal pathology)

A
  • Inflammation of cornea: neutrophils, lymphocytes, and plasma cells
  • Vascularization: vessels migrate to areas of injury
    o Corneal ulceration: takes ~4 days for vessels to start growing then they grow at a rate of 1 mm/day
    o *red ring=trying to heal it, white rim=inflammatory infiltrate
38
Q

What is episclera?

A
  • Loose connective tissue between conjunctiva and sclera
39
Q

What is sclera?

A
  • Dense connective tissue between episcleral and uvea
40
Q

What is the function of the sclera and episclera?

A
  • Continuous with cornea, together they comprise fibrous layer of eye=structural support
  • Protection of intraocular structures
  • Insertion of extraocular muscles
41
Q

Episcleritis

A
  • Nodular, focal and diffuse forms
  • Superficial disease
  • DOES NOT AFFECT DEEPER OCULAR STRUCTURES
  • Immune-mediated inflammation of episcleral (mixed inflammation)
42
Q

Scleral coloboma

A
  • Focal absence of sclera
43
Q

Scleritis

A
  • Causes: immune-mediated, traumatic, infectious agents
  • DEEP disease, affects deeper structures: uvea and retina
44
Q

Necrotizing scleritis

A
  • Collagen degradation
  • Avulsion of extraocular muscles

SYSTEMIC PATHOLOGY 3 (6 decks)

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