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Easter term fourt hyear > Ophthalmology uveitis and glaucoma > Flashcards

Ophthalmology uveitis and glaucoma Flashcards

1
Q

What are the two parts of the ciliary body

A

Pars plicata which produces aqueous and is the origin of the zonules
Pars plana which merges with the retina

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2
Q

What is the choroid

A

A layer of pigmented, vascular and lymphoid tissue behind the retina

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3
Q

Where is the reflective tapetum found

A

Within the inner choroid

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4
Q

Function of the choroicapillaris

A

To supply nutrients to the inner retina via retinal pigment epithelium

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5
Q

What is anridia and which domestic species does it affect

A

Lack of iris
Due to mutation in pax-6 homeobox genes; out of domestic species just horses seem to be affected

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6
Q

What does correctopia mean

A

Abnormal pupil position

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7
Q

Where is an iris coloboma usually seen

A

Ventrally

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8
Q

What does dyscoria mean

A

Abnormal pupil shap

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9
Q

What is the most common congenital defect of the uceal tract

A

Persistent puppilary membranes = vascular remnants from development; can cause cataract

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10
Q

What sections of uveal tract could uveitis affect

A

Anterior = iris
Intermediate = ciliary
Posterior = choroid

If all inflamed = panuveitis

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11
Q

What is rubeosis iridis

A

Red tinge to iris due to formation of new blood vessels in uveitis

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12
Q

WHy might we get a reduction in intraocular pressure in uveitis

A

Due to loss of function of the ciliary body

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13
Q

What is the classic triad of signs in uveitis

A

Miosis
Photophobia
Inflammatory cellular involvement

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14
Q

What are the main infectious causes of uveitis in the cat

A

TIP, FIV, FeLV, Toxoplasma

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15
Q

What infection in the cat causes pyogranulomatous inflammation and vasculitis with prominent rubeosis iridis

A

Feline infectious peritonitis (FIP)

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16
Q

How do common causes of uveitis differ in the dog and cat

A

In the dog it is mostly idiopathic and non-infectious; commonly see trauma and lens induced uveitis

In cats usually infectious

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17
Q

What causes lens induced uveitis

A

Gradual leakage of lens proteins (soluble) through lens capsule; triggers immune response since these antigens are ‘foreign’

Seen in diabetes as lens expands but capsule doesn’t

Get very dark brown iris

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18
Q

What type of uveitis is associated with dark brown iris

A

Lens induced

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19
Q

What is reflex uveitis

A

Specific traumatic uveitis condition; corneal injury leads to trigeminal nerve response to cause miosis; whole eye muscle ends up in spasm

Need atropine to stop this

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20
Q

What is Vogt-Koyanagi-Harada like syndrome

A

Autoimmune reaction against melanin-associated antigen in pigmented uvea and skin
–> Causes autoimmune uveitis and skin depigmentation
–> Seen in Japanese Akitas and Samoyeds

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21
Q

What common eye neoplasm in cats cause lead to uveitis

A

Leukaemia lymphocarcoma complex

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22
Q

What tumour can cause intraocular inflammation in the eye and what does this mean for tumour prognosis

A

Lymphoma
= automatically stage 5

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23
Q

What infectious agents can cause uveitis in the dog

A

Canine adenovirus
Agents from abroad e.g leishmania, borrelia, ehrlichia

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24
Q

What is different about iridal melanoma in dogs vs cats

A

Benign in dogs
Often malignant in cats

25
Q

What may a pink mass appearing through the pupil be

A

Ciliary body adenoma or adenocarcinoma

26
Q

What is iris atrophy and what is a differential for is

A

Acquired condition where iris becomes translucent with irregular pupillary margin and sluggish pupillary light reflex
–> Especially profound in poodles and see holes in iris

Differential = coloboma but this is acquired

27
Q

Describe the redness seen in an eye with glaucoma (compared to with conjunctivitis)

A

> Vessels are engorged so looks more red
But no redness between vessels

Because this is due to high pressure in vessels NOT due to cytokines

28
Q

4 key symptoms of glaucomatous eye

A
  • Red eye: engorged vessels
  • Painful eye (acute) with corneal oedema
  • Pupil dilation
  • Blind eye due to optic disc cupping
29
Q

How does glaucoma cause blindness

A

Because pressure forces the optic disc backwards, pushes on lamina cribrosa through which the optic nerve axons pass and kills of ganglion cell bodies

30
Q

Movement of fluid from production to leaving

A

Produced by the ciliary body, flows through pupil into anerior chamber, drains through trabecular meshwork to the ciliary cleft and out via drainage vessels

31
Q

Do we ever get glaucoma due to overproduction of aqueous

A

No

32
Q

What specific type of glaucoma is the beagle prone to

A

Open angle type
Iridocorneal angle is open but the trabecular meshwork is blocked by proteoglycan build up

33
Q

What tumour can get stuck in the iridocorneal angle

A

RIng melanoma

34
Q

Is glaucoma usually primary or secondary in cats

A

Secondary
- Due to inflammation (uveitis) or neoplasia

35
Q

What cause of glaucoma are we more likely to see in terriers or border collies and why

A

Secondary to lens luxation
Due to inherited weakness in the zonule
–> Acute glaucoma

36
Q

What is iridodonesis

A

Wobbling of the iris without the support of the lens behind it
e.g in lens luxation where lens then moved posterior

37
Q

Signs we will see in lens luxation glaucoma

A

If luxated anteriorly see lens in front of eye

Other signs: iridodonesis (wobbling of iris without lens support), corneal oedema in centre where lens abutted endothelium, aphakic crescent

38
Q

Which tonometry method is good for very small eyes e.g birds

A

Tonovet tonometer (= rebound)

39
Q

How can glaucoma occur secondary to anterior uveitis

A

Synechiae block movement of fluid through pupil
Inflammatory swelling of ciliary cleft closes angle
Inflammatory debris collecting in and blocking the trabecular meshworm

40
Q

In what breed can you get blockage of iridocorneal angle due to pigment deposition WITHOUT melanoma

A

Cairn terrier

41
Q

How can glaucoma occur secondary to neoplasia

A

Either by large solid mass blockin the iridocorneal angel
Or neoplastic cells (e.g lymphoma) blocking trabecular meshwork

42
Q

When do we see ciliary cleft collapse

A

End stage glaucoma
Tumour

43
Q

What is the emergency treatment initially done for glaucoma

A

IV mannitol at 20% 10mg/kg over half an hour
–> To reduce intraocular pressure

44
Q

3 methods of reducing aqueous production

A
  1. Carbonic anhydrase inhibitors (NB: old drugs cause metabolis acidosis)
  2. beta blockers to constrict the ciliary body
  3. Surgical reduction: freezing or laser
45
Q

When are beta blockers useful in reducing aqueous production

A

In low tension glaucoma e.g 30mmHg BUT we usually get presented with much higher pressures than this

46
Q

Why is endoscopic laser of ciliary body complex and hard to do (to reduce aqueous production)

A

Need to remove the lens to get the aqueous in

47
Q

Why is there a high risk of fibrosis in response to foreign material in the eye e.g in drainage implants

A

Due to TGFbeta action

48
Q

What is the unconventional drainage pathway for aqueous and how might we open it pharmacologically

A

= through ciliary body and is usually opened up in response to prostaglandins in inflammation
- Fluid goes via suprachoroidal spaces to uveoscleral drainage pathway

  • We could use PGF2alpha, Latanoprost
49
Q

WHat are some problems we can face with the vigor drainage implant

A
  • Get secondary prostaglandin mediated production of new aqueous which is full of fibrin
  • FIbrin can block the microchannels and stop drainage
50
Q

If we are doing an eye enucleation do we need to worry about tying off the optic nerve

A

No
- The vessels on either side of it are small in the dog and cat so will stop bleeding with firm pressure

51
Q

WHat is limbal flush

A

See hyperaemia especially visible at the limbus in uveitis because the vessels of the ciliary body are there so when inflamed, cytokines gives hyperaemia

52
Q

Differentiating conjunctivitis from uveitis simple

A

Conjunctivits: redness on globe AND eyelid mucosa
Uveitis: redness just on the globe; esp at limbus

53
Q

In which cause of red eye do we see a constricted pupil and in which do we see a dilated one

A

Constricted pupil in uveitis
Dilated one in glaucoma

54
Q

WHich cause of red eye is more liekly to present with serous/mucoid/purulen discharge

A

Conjunctivitis
- The others just mainly lacrimation

55
Q

Pain severity of different causes of red eye

A

Most painful = glaucoma
Then uveitis
Conjunctivitis painfree or mild

56
Q

Which cause of conjunctivitis could lead to blindness and what type of blindness

A

Distemper
= central blindness

57
Q

In which cause of red eye are the aqueous and iris ost affected

A

Uveitis

58
Q

What cause of red eye is most likely to present with hypopyon flat layer of pus

A

Severe uveitis (= from aqueous)

59
Q

What might cause a sluggish pupillary light reflex and irregular pupillary margins

A

Iris atrophy
Esp profound in poodles

Easter term fourt hyear (48 decks)

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