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VMS2007 > Eye Pathology > Flashcards

Eye Pathology Flashcards

I (general features), II (the cornea), III (the uvea), IV (the lens and the retina)

1
Q

Describe the function of the eyelid

A

protect from light and trauma
distribution of tear film
production of lipid component of tear film
removal of excess tears and foreign material
communication

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2
Q

Describe the functions of the cornea

A

secretory (mucous contribution to tear film)
immunity (CALT)
mobility

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3
Q

Describe the function of the sclera

A

provide external support to the globe contents
aid in movement of globa

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4
Q

Describe the function of the third eyelid

A

protect the cornea
distribute tear film
nictitans gland contributes to aqueous component of tear film

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5
Q

What are the 3 components of the tear film and the function of the tear film

A
  1. mucous (goblet cells in conjunctiva)
  2. aqueous (lacrimal and nictitans glands)
  3. lipid (Meibomian gland)

lubrication, immune mediation, removal of debris, cornea nutrition

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6
Q

Define eNtropion

A

internal rolling IN of the eyelid

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7
Q

Define eCtropion

A

external rolling OUT of the eyelid

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8
Q

Give some potential causes for ectropion/entropion

A

congenital, developmental, senile, trauma, inflammation, neurological, iatrogenic, nasal fold trichiasis

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9
Q

Define distichia

A

abnormal hairs arise from the Meibomian gland and exit out of the eyelid margin

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10
Q

Define blepharitis and give the different types

A

inflammation of the eyelids, general or local

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11
Q

Define chalazion

A

sterile granulomatous inflammation in response to the leakage of Meibomian secretion (a kind of local blepharitis).

commonly caused by lipid leakage into the subconjuncitval space

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12
Q

Define a stye

A

suppurative inflammation of the adnexal glands (a type of local blepharitis)

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13
Q

Name the most common eyelid masses in cats and dogs

A

cats = SCC, 91% likely to be malignant
dogs =sebaceous adenomas

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14
Q

Define “Cherry Eye”

A

protrusion of the nictitans gland
prolapsed third eyelid
caused by a congenital laxity in the connective tissue anchoring the gland to the cartilage

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15
Q

Give the CS of conjunctivitis

A

hyperaemic and oedematous conjunctiva (vasodilation, appears red and swollen)
ulceration
fibrosis

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16
Q

Name the possible causes of conjunctivitis

A

Infectious (common in cats, especially FHV, calciviruses and Clamydia felis. uncommon in dogs. see pink eye in cows caused by Moraxella bovis.)

Non-infectious (commonly allergens and environmental irritants. in dogs, dry eye is the most common cause.)

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17
Q

Define Dry Eye (KCS)

A

Immune-Mediated Keratoconjunctivitis Sicca
when the body recognises self-antigens in the lacrimal gland, which starts a T-cell response against the antigens, decreasing tear film quality and quantity.
lack of tear film = chronically exposed cornea, left untreated = blindness

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18
Q

Define the Schirmer Tear Test (STT)

A

diagnostic for dry eye
<10mm tea production in 1 minute

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19
Q

Name some common causes of KCS

A

developmental
metabolic (hyperadrenocorticism, DM)
neoplastic
neurological (facial nerve trauma)
inflammation
infection (distemper virus, FHV-1)
immune-mediated (MOST COMMON)
iatrogenic (cherry eye removal)
traumatic
toxic

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20
Q

Define retained spectacles

A

an issue in snakes, caused by a poor environment and a lack of correct humidity
occurs when the scale that covers the eye cap (the spectacle) does not come off with the rest of the shed skin

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21
Q

Describe the normal corneal structure

A

tear film, corneal epithelium, corneal stroma (thickest part), descemet’s membrane and the corneal endothelium

^ from outside in

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22
Q

Describe the function of the cornea

A

maintain globe structure
transparency for vision

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23
Q

Define a corneal oedema

A

endothelial cell loss, often caused by ulceration, leading to the tear film penetrating into the cornea

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24
Q

What are the causes of corneal oedema

A

ulceration
internal ocular disease (glaucoma, uveitis)
limbal disease

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25
Q

Define corneal ulcers

A

injury to the epithelial cells –> exposed stroma
= corneal ulceration

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26
Q

How does the eye heal corneal ulceration?

A
  1. epithelial cells on the edge will proliferate and undergo structural changes
  2. fibronectin polymerases form on wound, providing an anchoring for ECM
  3. migration phase (new epithelial cells slide over the wound and cover the gap)
  4. proliferation phase (basal cells transform into squamous cells over weeks)
  5. attachment phase (new hemidesmosome attachments anchor to the stroma)
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27
Q

CS of corneal ulceration

A

pain
conjuncitval hyperaemia
corneal oedema
corneal neovascularisation

28
Q

Common causes of corneal ulceration

A

developmental
inflammation
infection
dry eye
traumatic

29
Q

Define a suppurative keratomalacia

A

“Melting Ulcer”
caused by proteinase and collagenase production

30
Q

Define a descemetocele

A

stromal liquefaction that reaches the Descemet’s membrane, resulting in the eye bulging forward (stroma has been lost completely)

31
Q

Define a corneal dystrophy

A

defects in the structure or function of one or more corneal components, not triggered by injury or systemic disease

32
Q

Name some types of corneal deposits

A

central corneal lipidoses (benign and non-progressive)
systemic lipid abnormalities (peripheral stromal deposition of lipid)

33
Q

Define feline corneal sequestrum

A

necrotic cornea, recognised as a discrete orange-brown discolouration of the cornea, affecting one or both eyes

34
Q

Define SCCED

A

spontaneous chronic corneal epithelial deficit
non-healing, superficial ulceration of the epithelial layer of the eye

35
Q

Define keratitis

A

inflammation of the cornea

36
Q

Define Pannus keratitis

A

Chronic, superficial
bilateral, progressive inflammatory disease of the canine cornea
lesion is made up of superficial corneal vascularisation infiltration of granulomatous tissue and pigmentation

37
Q

Define feline eosinophilic keratitis

A

unilateral or bilateral “fluffy” white superficial stromal keratitis
lesion is a mixture of macrophages, plasma cells, fibroblasts, mast cells and a few eosinophils
idiopathic !

38
Q

What are the 3 parts of the uvea

A

iris, ciliary body and choroid

39
Q

Define goniodysgenesis

A

incomplete development of the iridocorneal angle, leading to incomplete remodelling of the anterior chamber.
increases the risk for glaucoma

40
Q

Define glaucoma

A

Diseases characterised by a persistent elevation of intraocular pressure (IOP) due to a decreased outflow of aqueous humour (leading it to build up inside the globe)

41
Q

Define uveitis

A

the presence of inflammatory cells or fibrin in the uveal tract

42
Q

Define anterior uveitis (iridocyclitis)

A

inflammation of the CB and/or iris

43
Q

Define posterior uveitis (choroiditis)

A

inflammation of the choroid

44
Q

Define panuveitis

A

inflammation of the choroid and CB and/or iris

45
Q

Define endophthalmitis

A

inflammation of the uveal tract (CB, iris and choroid), retina and adjacent components

46
Q

Define panophthalmitis

A

inflammation of all tunics +/- the orbit

47
Q

Give the CS of uveitis

A

corneal oedema
conjunctival hyperaemia
aqueous flare (protein within anterior chamber)
hypopyon (cloudy, moving material in the eye)
hyphema (RBCs in anterior chamber, haemorrhage)
rubeosis iridis (“red iris”)
low IOP (hypotony, due to decreased aqueous humour production)
miosis (narrowed pupils)

48
Q

Define ACAID

A

Anterior Chamber Associated Immune Deviation (ACAID)

49
Q

What makes up ACAID

A

anti-inflammatory cytokines
sequestration from immune system
lack of distinct lymph supply
blood-to-aqueous and blood-to-retinal barriers

50
Q

What is the function of ACAID ?

A

The immune privilege of the eye
some ocular and foreign antigens are not recognised as “self” but are still tolerated by the eye
ACAID gives the eye selective unresponsiveness with specific effector responses to mediate ocular immune responses to foreign antigens

51
Q

Name the 3 phases of the ACAID system

A
  1. ocular –> ocular antigen-presenting cells start producing a specific protein relevant to the foreign antigen and exit the eye
  2. thymic –> they will go to the thymus, where they stimulate the production of a unique population of NKT cells (NOT CD4+ or CD8+)
  3. splenic –> they will go to the spleen, where they meet with the NKT cells and form an immunosuppressive environment. they produce ACAID Treg cells, which travel back to the eye to reduce the cell-mediated immune response and down-regulate inflammation
52
Q

Name some causes of uveitis

A

reflex (after keratitis)
immune-mediated (lens-induced)
–> phacolytic = response to leaked lens proteins
–> phacoclastic = response to ruptured lens capsule
uveodermatologic syndrome (autoimmune process targeted against melanocytes)
infection (parasites uncommon, fungi, bacteria, protists, viruses esp. FIPV and ERU)
penetrating trauma
systemic vascular disease
idiopathic

53
Q

Name some sequelae of uveitis

A

fibrovascular membranes form in response to inflammation, most commonly preiridal (PIFM). can result in distortion of pupillary margin and block aqueous outflow (=glaucoma !!)

synechiae are adhesions between an inflamed iris and cornea or lens. cause pupillary block (–> impaired aqueous outflow –> glaucoma !!)

cataracts are caused by impaired lens nutrition

retinal detachment due to inflammation of the choroid

Phthisis bulbi is an end-stage globe, shrunken and disorganized

54
Q

Name some common uveal neoplasms

A

Melanomas
Neuroectodermal tumours
nerve sheath tumours
metastatic neoplasia
iridial neoplasms (–> block aqueous outflow –> glaucoma !!)

55
Q

Define ectopia lentis

A

displacement of the lens

56
Q

What are the causes of ectopia lentis

A

primary (gene mutation, insufficient or abnormal zonular fibres)
secondary (glaucoma, trauma, uveitis, space occupying neoplasms, cataracts)D

57
Q

Define cataracts

A

opacities of the lens

58
Q

How do we classify cataracts ?

A

location (cortical, nuclear, subcapsular)
extent
- incipient <15%
- immature >15%
- mature, complete obstruction
- hypermature, lens starts shrinking

59
Q

Name some causes of cataracts

A

Diabetes (glucose is the main energy source for lens fibres. the rate limiting step is an enzyme, which can get saturated in time of high glucose)
Trauma (irradiation, lens capsule rupture)
Developmental
Glaucoma
Uveiitis
Toxins
Nutritional excess and deficiency

60
Q

What is the most common neoplasm of the cat eye?

A

Feline Post-Traumatic Ocular Sarcoma (FPTOS)

61
Q

Define a coloboma

A

cyst-like outpouching of dysplastic neuroectoderm caused by failure of complete fusion of the optic fissure

62
Q

Define retinal detachment

A

detachment between the retinal pigmental epithelium and the neurosensory layers at the level of the photoreceptors

will see exudate between the separated layers and “clubbing” of retinopigmented epithelium

63
Q

Define Outer Retinal Atrophy

A

degenerative condition (heritable) resulting in photoreceptor atrophy and plexiform layer atrophy. leads to blindness

64
Q

What are the two causes of outer retinal atrophy ?

A

PRA = progressive retinal atrophy
SARDS = sudden acquired retinal degeneration syndrome

65
Q

Define Inner Retinal Atrophy

A

most commonly glaucoma, retinopathy that leads to loss of vision due to loss of retinal ganglion cells due to increased IOP.

66
Q

Name the CS of glaucoma

A

corneal oedema
keratitis
red eye
buphthalmia (big eye)
mydriasis (dilated pupil)

CORe BuM !!

67
Q
A

VMS2007 (14 decks)

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