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Systemic Pathology II > Ocular > Flashcards

Ocular Flashcards

1
Q

What are the 3 tunics of the eye? What structures are in each? What is the function of each?

A
  1. FIBROUS: cornea, sclera; shape, protection, light refraction
  2. VASCULAR/UVEA: iris, ciliary body, choroid; pigmented and vascular for light reflection, scattering, nutrition, and waste removal
  3. NERVOUS: retina, optic nerve; electric and chemical signaling to brain
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2
Q

What is the purpose of the aqueous humor, lens, and vitreous humor?

A

light refraction and internal pressure maintenance (must be transparent!)

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3
Q

Eye anatomy:

A
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4
Q

What are 6 common clinical presentations of ocular disease?

A
  1. blindness resulting from alterations in the cornea, lends, or humors, damage to the retina or optic nerve, and extraocular lesions in the brain’s occipital lobes
  2. conjunctival discharge
  3. swelling and pain (chemosis)
  4. sensitivity to light
  5. excessive (epiphora) or decreased lacrimation due to damage to the glands
  6. opacity of the cornea or lens
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5
Q

What is exophthalmos? Proptosis? Buphthalmos? Enophthalmos? Hyphema? Hypopyon?

A
  • protrusion of eyes within the orbit
  • protrusion of eyes out of the orbit, typically due to fractures or space-occupying lesions
  • enlargement of the eyes
  • sunken in eyes, typically caused by orbital fractures or muscle atropy
  • blood in anterior chamber
  • pus in anterior chamber
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6
Q

What is this?

A

buphthalmos - enlarged eye

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7
Q

What is this?

A

proptosis - protrusion of eye out of orbit

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8
Q

What is this?

A

exophthalmos - protrusion of eye within orbit

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9
Q

What is this? What are some possible differential diagnoses?

A

hyphema - blood in anterior chamber

hypertension caused by hyperthyroidism or CKD

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10
Q

What is this?

A

hypopyon - pus in anterior chamber

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11
Q

What is the most common cause of congenital ocular abnormalities?

A

infectious, nutritional, or genetic teratogens that cause defective cell signaling during organogenesis in embryonic development

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12
Q

What is microphthalmia?

A

congenital/hereditary anomaly where one or both eyes are abnormally small and are histologically malformed and disorganized

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13
Q

What is synophthalmos?

A

congenital/hereditary anomaly where two eyes are present in a singular orbit caused by incomplete separation of the paired globes

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14
Q

What is cyclopia?

A

congenital/hereditary anomaly where there is a singular, central eye

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15
Q

What is the most common cause of cyclopia and synophthalmos in sheep? When in embryonic development is this able to happen?

A

ingestion of Veratrum californicum, which contains cyclopamine and jervine that are able to cause the failure of the prosencephalon to divide into the 2 lobes of the cerebral hemispheres

day 14-15 of gestation, when this division is beginning to occur

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16
Q

What vasculature is present in the embryonic eye? How does this develop during gestation?

A

hyaloid artery branches and supplies blood to different structures of the eye

these vessels should regress 2-4 weeks after birth

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17
Q

What is persistent pupillary membrane? How does it affect the animal?

A

persistence of the vascular fetal structure that covers the pupil and causes uveal/vascularized strands to develop across the pupil iris-to-iris, iris-to-lens, or iris-to-cornea

most common in cats —> does not progress, is not painful, and does not affect vision

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18
Q

What are the 5 layers of the normal cornea?

A
  1. epithelium - nonkeratinized stratified squamous
  2. basement membrane
  3. stroma - parallel collagen fibers (clear spaces that look like edema are common artifacts upon fixation)
  4. Descement’s membrane - produced by endothelium
  5. endothelium
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19
Q

What part of the eye is most susceptible to damage?

A

cornea —> outermost, exposed layer

(allow light to enter)

20
Q

What are 5 common responses of the cornea to injury?

A
  1. edema - opacity
  2. inflammation - keratitis
  3. vascularization*
  4. pigmentation*
  5. fibrosis*

*chronic, lymphoplasmacytic

21
Q

Chronic corneal damage:

A
  • inflammation
  • vascularization
  • pigmentation
  • results in opacity, pigmentation, and vision effects
22
Q

Keratitis and healing:

A
  • opacity, pigmentation, vascularization
  • decreased opacity and vascularization
23
Q

What are 4 common causes of keratitis? What specific bacterium and virus cause this?

A
  1. irritation - entropion, eyelid masses, particulate material
  2. desiccation/exposure - lagophthalmos (incompletely closed eyelids common in brachycephalic breeds), buphthalmos (glaucoma), exophthalmos (orbital masses)
  3. repeated corneal ulceration
  4. trauma

Moraxella bovis, feline herpesvirus-1

24
Q

What is indicative of acute keratitis?

A

accumulation of neutrophils cause keratomalacia (melting ulcer) due to excretion of proteases and metalloproteases

  • endogenous: inflammation
  • exogenous: bacteria, fungi

(basophilic band = neutrophils)

25
Q

What is indicative of chronic keratitis?

A

lymphoplasmacytic inflammation leads to epidermalization (eye becomes “skin-like”) —> acanthosis, melanosis, vascularization, stromal scarring (fibrosis)

26
Q

What is chronic superficial keratitis/conjunctivitis? What is the most likely etiology? What animal is predisposed?

A

pannus - fleshy gray-pink superficial tissue formation in the limbus where the sclera meets the cornea (no ulceration!)

immune-mediated reaction to UV light modifying cornea-specific antigens

German Shepherds

27
Q

What are boxer ulcers? At what age does it most commonly develop? What is the most likely cause?

A

indolent (lazy) ulcer that is a non-healing, superficial corneal erosion

middle to older age

spontaneous or traumatic defect in epithelial adhesion to stroma

28
Q

What are the 2 histological characteristics of boxer ulcers?

A
  1. non-adherent hyperplastic epithelium
  2. clefts between epithelium and stroma
29
Q

What is eosinophilic keratitis?

A

proliferative, placoid lesions of white material common in cats and horses

30
Q

What cytology is indicative of eosinophilic keratitis?

A

impression smear = EOSINOPHILS. granules, epithelial cells, mast cells

31
Q

What is corneal sequestrum? What is the likely cause? How does it affect the eyes?

A

amber/black stromal pigmentation commonly seen in Persian and Siamese cats

corneal disease: injury (trauma) and FeHV-1

  • stromal hyalinization (necrosis) causes epithelium to slough off
  • prone to bacterial colonization
32
Q

What is the most common cause of fungal/mycotic keratitis? In what animals is this most common?

A

opportunistic Aspergillus or Fusarium infection of corneal wounds being treated with antibiotics or corticosteroids

horses in warm and humid climates

33
Q

What lesion is characteristic of fungal/mycotic keratitis? What tropism does it typically have? What does this cause?

A

destructive, deep stromal, ulcerative suppurative keratitis with keratomalacia (liquefaction)

Descement’s membrane —> ruptures, causing exudate spillage into the anterior chamber (endophthalmitis)

34
Q

Fungal/mycotic keratitis, keratomalacia:

A
35
Q

What causes corneal degeneration? What 3 metabolic disorders are most common?

A

accumulation of lipids and calcium

  1. high fat diets - amphibians, reptiles, and birds fed high amounts of crickets and mealworms
  2. hyperadrenocorticism, hypothyroidism, diabetes
  3. hypercalcemia
36
Q

What is characteristic in the histology of lipid keratopathy?

A
  • cholesterol clefts
  • oil red O stained fat droplets
37
Q

What is the most common origin of corneal neoplasms?

A

extension from adjacent tissue (conjunctiva)

38
Q

In what animals is squamous cell carcinoma of the eyes most common? What is the cause?

A

horses, Hereford cattle, cats

unpigmented skin around the eye is damaged by UV light and it extends from the conjunctiva or eyelids

  • ulceration and discharge
39
Q

What is the most common cause of corneal neoplasms in dogs? What is a major risk factor?

A

dogs with chronic keratitis develop hyperplasia, which develops into dysplasia and neoplasia

use of immuno-modulating drugs

40
Q

What is corneal dermoid?

A

congenital, non-neoplastic, choristoma - where normal tissue not usually found in the eye is present

41
Q

What a staphyloma? What is it commonly lined by? What is thought to be the cause?

A

circumscribed outpouching of the sclera due to weakening or thinning

uveal tissue —> pigmentation from choroid makes it look like a melanocytic tumor

increased intraocular pressure from glaucoma, trauma, or scleritis

42
Q

Staphyloma:

A

outpouching, can include cornea

43
Q

What is granulomatous/necrotizing scleritis? What is characteristic? In what animals is it most common?

A

idiopathic painful, rapidly-progressive inflammation that can involve the entire sclera, along with the uvea and retina, leaving the contralateral eye at risk

robust inflammation containing epithelioid macrophages, multinucleated giant cells, and collagenolysis

dogs

44
Q

What is the most prevalent scleral disease of dogs? How does it look grossly?

A

nodular granulomatous episcleritis (NGE)

firm, painless, moveable, smooth, gray-pink mass/swelling

45
Q

What is characteristic of the histology of nodular granulomatous episcleritis (NGE)? What does it commonly respond well to?

A

discrete granulomas lacking collagenolysis

immunosuppressive therapy

46
Q

What is the most common neoplasm of the sclera? What must it be differentiated from in cats?

A

limbal melanocytoma —> benign (no metastasis), large, extension into cornea, most common in dogs

iris melanoma extension

47
Q

What is characteristic of the histology in limbal melanocytoma?

A

heavy pigmentation with minimal atypia and absent mitoses

  • benign!

Systemic Pathology II (24 decks)

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