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Module 14 Comparative Ophthalmology > Comparative Ophthalmology > Flashcards

Comparative Ophthalmology Flashcards

1
Q

How long is a phenol red thread test left in the eye for?

How is it measured?

Normal measurement in rabbits?
Birds?

A

15-60secs

Colour changes from yellow to red

Rabbits 24mm in 15secs
Birds 22mm in 15secs

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2
Q

How long is a endodontic absorbent paper point test left in the eye for?

How is it measured?

A

60secs

Measure bent wetted bit

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3
Q

What is the STT for rabbits?

Phenol red thread test?

A

5 +/-3 mm/min

24 +/- 4mm/min in 15secs

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4
Q

What is the STT for birds?

Phenol red thread test?

A

5 +/-3 mm/min

22 +/- 4mm in 15secs

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5
Q

What is a more accurate way of measuring a visual pathway in exotics;
Menace or dazzle reflex?

A

Dazzle reflex

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6
Q

Do rabbits with mildly or heavily pigmented irides have a poorer response with atropine/tropicamide?

A

Heavily pigmented irides

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7
Q

Which drug is used to dilate reptiles eyes?
Birds eyes?

How much?

Why doesn’t tropicamide/ atropine work?

A

Rocuronium
Rocuronium

0.2-0.4mg, use 20mu l drop

Pupil controlled by striated muscle under voluntary control (not autonomic)

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8
Q

What is in focus at dioptre or;
0
+10
+20

A

0 retina
+10 lens and iris
+20 cornea

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9
Q

What is normal tonometry in rabbits?

A

13+/-6

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10
Q

What is normal tonometry in birds?

Owls

A

20+/-4

11+/-4

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11
Q

Should a low or high frequency transducer be used in exotics with small eyes?

A

High (>10Mhz)

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12
Q

Do rabbits have one or two puncta on each eye?

A

One

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13
Q

Is the cornea in rabbits thicker or thinner than dogs?

What size?

A

Thinner

355mum

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14
Q

How do rabbit endothelial cells differ from cats and dogs in regards to repair?

A

Rabbit endothelial cells can regenerate and divide (in dogs/ cats they enlarge to fill gaps)

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15
Q

What type of fundus does a Lagomorph/ rabbit have?

Where is the optic disc in comparison to the midline?

Do rabbits have a tapetum?

A

Merangiotic vascular pattern

Dorsal to the midline

No tapetum

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16
Q

Do rabbits have a tapetum?

A

No

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17
Q

Do rabbits get optic disc cupping easily or not so easily with glaucoma in comparison to companion animals?

A

Easily

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18
Q

Do rabbits have a complete or incomplete orbit

A

Complete

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19
Q

What glands to rabbits have in the orbit?

Which gland is known as the Hardarian gland?

A

Lacrimal gland
Accessory lacrimal gland (3 lobes)
Superficial and deep gland of the TEL

Deep gland of the TEL

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20
Q

Where are meibomian glands in birds?

A

Don’t have any

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21
Q

What muscle in birds pulls the TEL membrane to cover the cornea?

Which nerve innervates this?

A

Pyramidalis muscle

CN VI

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22
Q

Does the TEL in birds have a gland?

A

No

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23
Q

Which glands does the eye have in a bird?

A

Lacrimal gland

Hardarian gland

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24
Q

How many lacrimal puncta does a bird have, one or two?

A

Two

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25
Q

Is the avian orbit complete or incomplete?

A

Incomplete

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26
Q

Which muscle makes up most of the iris in birds?

A

Striated muscle

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27
Q

Does the Retina in birds have a tapetum?

It is avascular so where does it get its nutrition from?

A

No tapetum

Choroid

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28
Q

What is the pecten in birds?

A

Heavily pigmented and variably pleated highly vascularised fan like structure that projects from the optic nerve head in to the vitreous

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29
Q

What is the % of decussation at the optic chiasm in birds?

What does this mean with the PLR?

A

100%

No consensual PLR

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30
Q

What do snakes have instead of eyelids?

A

Spectacles

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31
Q

What layer of the spectacle is shed during ecdysis?

What does it look like just before shedding?

Can the snake see during this?

Can topical meds penetrate the spectacle?

A

Anterior layer

Cloudy due to thickening and accumulation of fluid between the new surface layer and the layer that will be shed

No

No

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32
Q

Which glands (2) in reptiles other than snakes secrete tears?

A

Lacrimal glands

Harderian glands

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33
Q

Which reptiles don’t have a nasolacrimal duct?

A

Chelonians

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34
Q

How do reptiles other than snakes accommodate the lens?

How do snakes do this?

A

Ciliary body

Increased pressure on the vitreous causing forward movement of the lens

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35
Q

Which enucleation technique should be used for rabbits?

Why?

A

Subconjunctival

Orbital plexus can bleed significantly if damaged

36
Q

What can cause a dramatic periodic exophthalmos in rabbits?

A

Mass around the jugular vein (thymoma/ thyroxine carcinoma)

37
Q

Which bacteria are retrobulbar abscesses in rabbits usually caused by?

Cause?

A

Pasteurella

Tooth root abscesses

38
Q

What is the treatment of orbital gland prolapse in the rabbit?

Which glands are prone to prolapse?

A

Replacement and Pocketing of the gland

Harderian gland (superficial and deep glands of the third eyelid)

39
Q

Which species gets conjunctival overgrowth?

Name?

What is the treatment?

Cause?

A

Rabbits

Pseudopterygium/
conjunctival centripetalisation

Radial incisions made, conjunctiva sutured to the sclera
(Simple excision results in re growth)

Unknown

40
Q

What are the most common bacterial isolates of conjunctivitis in rabbits (2)?

A

Staphylococcus

Pasteurella

41
Q

What does treponema cuniculi in rabbits cause?

What is the common name?

Transmission?

Diagnosis?

Treatment?

A

Blepharitis

Rabbit syphilis

Infected genitals of mother to neonates

Spirochete on conjunctival cytology

Parenteral penicillins

42
Q

What is the most common cause of dacryocystitis in rabbits?

Treatment?

A

Dental disease

Flushing nasolacrimal duct
Dental tx
Long term systemic ABs

43
Q

How is entropion treated in rabbits?

What complicates this?

A

Surgery

Blepharitis

44
Q

How Soon should an ulcer in a rabbit heal?

A

Within 7 days

45
Q

Which drug can cause KCS in rabbits?

What is the treatment for KCS in rabbits?

A

Trimethoprim sulfamethoxazole

Topical Cyclosporine

46
Q

What is the diagnosis of eosinophilic keratitis in rabbits?

Treatment?

A

Cytology (but rabbit eosinophils look like heterophils, rabbit neutrophils)

Topical steroids +/ cyclosporine

47
Q

What is the cause of early cupping of the optic nerve in rabbits with glaucoma?

Cause?

Is treatment effective?

A

Lack of well formed lamina cribosa

Goniodysgenesis

No

48
Q

Rabbits can get lens induced uveitis causing white, vascularised, inflammatory lesions in the iris. What is thought to be the cause of these?

A

E cuniculi

49
Q

What are the causes of cataracts in rabbits?

Treatment?

A

Congenital/ hereditary
E cuniculi - mother to offspring, only causes a cataract when the it causes the lens capsule to rupture causing lens induced uveitis and cataract.

Cataract surgery

50
Q

What ocular signs does Infraorbital and periocular sinusitis cause in birds? Acute v chronic?

Treatment?

A

Acute - exophthalmos/ strabismus
Chronic - Enophthalmos

Sinus flushing and surgical debridement

51
Q

What can microphthalmos cause in birds?

Cause of this and anophthalmos?

A

Recurrent conjunctivitis

Hereditary?

52
Q

What is cryptophthalmus in birds?

Cause?

Is surgery successful?

A

Constriction of the eyelid aperture

Trauma
Inflammation
Inherited

No usually scar up again

53
Q

What are the ocular signs of hypovitaminosis A in birds?

Other signs?

Cause?

A

Periocular and conjunctival swelling
Ocular discharge

White plaques in and around the mouth
Laboured/ open mouth breathing
Nasal discharge + sneezing or dry crusted Nares

Exclusive high energy seed diet (esp sun flower seeds)

54
Q

What does poxvirus cause in birds?

A

Blepharitis
Eyelid oedema
Epiphora
Irritating at eyelids (need to prevent this - soften scabs with shampoo)

55
Q

What does knemidokoptes cause in birds?

Common name?

Treatment?

A

Scaly leg, beak, eye

Scaley leg

Ivermectin

56
Q

What are eyelid swellings in birds likely to be?

A

Cystic/ inflammatory secondary to sinusitis

57
Q

Which bird gets one eyed cold (conjunctivitis)?

A

Pigeon

58
Q

What is the treatment for cockatiel conjunctivitis?

Clinical signs?

A

Topical chlortetracycline, ophthcycline/ exocin

Severe conjunctivitis
Chemosis
Hyperaemia

59
Q

What is the cause of Amazon parrot keratitis and Mynah bird keratitis?

Clinical signs?

Treatment?

A

Stress and trauma of capture and transport

Transient ulcerations/ erosions

Self limiting with supportive care

60
Q

What is the treatment of uveitis in birds?

A 
Topical steroids/ NSAIDs
Curariform drops (mydriasis)
61
Q

What is the treatment of cataracts in birds?

What is the main factor that needs to be taken in to consideration before performing the surgery?

A

Phacoemulsification

Needs to be handleable as needs topical tx up to 6x daily

62
Q

What is the most common cause of retinal disease in birds?

A

Trauma

63
Q

What are the clinical signs of horners syndrome in birds?

Diagnosis?

Most likely cause?

A

Only ptosis

Phenylephrine

Trauma

64
Q

What does hypovitaminosis A cause in chelonians?

Treatment?

A

Eyelid swelling
chemotic conjunctiva
Resp issues

Oral May not be enough, so IM injections

65
Q

What can septicaemia in reptiles cause to the eyes?

A

Conjunctivitis

66
Q

What can be the cause of a retained spectacle in snakes?

Treatment?

A

Husbandry (low humidity)
Ill health
Mite- ophionyssus natricis

Increase humidity
Damn cotton wool

67
Q

What causes Bullous spectaculopathy?

What is it?

A

Blocked nasolacrimal duct causing tear fluid to build up subspectacular

Fluid between cornea and spectacle

68
Q

What is the treatment of subspectacular abscessation?

A

Excision of a triangle of spectacle and copious flushing

69
Q

What is the most common cause of uveitis in reptiles?

Treatment?

A

Gram negative infections (eg. Pseudomonas)

Systemic ABs
Topical anti inflammatories

70
Q

What can’t you use tonometry in snakes?

A

They have a spectacle

71
Q

What is the iris muscle of mammals?
Birds and reptiles?

What is needed for mydriasis in birds/ reptiles?

A

Mammals- autonomic innervation of smooth muscle

Birds and reptiles - striated muscle under voluntary control

Non depolarising muscle relaxant
Rocuronium bromide 0.2-0.4mg/eye

72
Q

What diopters are used in smaller eyes for;
Retina
Lens and iris
Cornea

A

0 retina
+10D lens and iris
+20 cornea

73
Q

What makes enucleating a rabbit more difficult?

A

Large retrobulbar venous plexus

74
Q

What is the annular pad in birds used for?

A

Nutrition and accommodation

75
Q

In birds is the fundus vascular or avascular?

A

Avascular

76
Q

What does the nasolacrimal gland in chelonians do?

A

Extra site of salt excretion

77
Q

Generally reptiles extraocular muscles are poorly developed except which one?

A

Lizards

78
Q

Generally reptiles have a well developed retrobulbar muscle except?

A

Snakes

79
Q

Generally reptiles have limited rotational movement except?

A

Chameleons

80
Q

In which of the following do you get scleral ossicles?
Lizards
Snakes
Chelonians

A

Lizards and Chelonians yes

Snakes no

81
Q

Reptiles have an equatorial pad other than which?

What does this do?

A

Snakes

Accommodation

82
Q

What is this?

A

Exophthalmus

Compromise to venous return
Thymoma
Stress
Retrobulbar disease

83
Q

Periocular swellings in reptiles are normally caused by gram positive or negative barriers?

A

Gram negative

84
Q

What can Chelonians get post hibernation?

Cause?

A

White corneal lesions

Too fat diet

85
Q

How many times do rabbits blink?

A

10-12 blinks per hour

Module 14 Comparative Ophthalmology (2 decks)

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