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NEU2 > Small animal ophthalmology 2 > Flashcards

Small animal ophthalmology 2 Flashcards

Feline ophthalmology, the eye and systemic disease, ophthalmic emergencies

1
Q

Describe the signs of conjunctivitis in the cat

A
  • Ocular discharge
  • Conjunctival hyperaemia
  • Uncomfortable but no pain
  • Pupil normal
  • Sneezing and rhinitis may be seen in younger cats
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2
Q

Describe neonatal ophthalmia in cats

A

Conjunctivitis beneath eyelid before eyes open (i.e. before 10-12 days)

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3
Q

What are common causes of conjunctivitis in the feline eye

A
  • Feline herpes virus
  • Calicivirus
  • Chlamydia felis
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4
Q

Describe symblepharon in the cat

A
  • Conjunctiva becomes so ulcerated that it sticks to itself

- Unlikely to be able to restore normal anatomy, likely to have corneal scarring

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5
Q

Describe the appearance of lipogranulomatous conjunctivitis in the cat

A
  • Eye not always sore, thickened or inflamed
  • Swelling on inner surface of upper and lower eyelids associated with Meibomian glands
  • Similar to styes
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6
Q

Outline the cause of lipogranulomatous conjunctivitis in the cat

A
  • May be associted with infection
  • Not fully understood
  • Some inflammatory component e.g. low level chronic infection of eyelid margins
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7
Q

Outline the treatment of lipogranulomatous conjunctivits in the cat

A

May need surgery to control if leads to irritation

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8
Q

What is Haws syndrome of the cat?

A

Haws = third eyelid

Haws syndrome is prolapse of the third eyelid

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9
Q

Describe the typical presentation of Haws syndrome in the cat

A
  • Vaguely unwell
  • Usually presented due to looking peculiar, not other neuro signs
  • Some low level lethargy
  • Diarrhoea
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10
Q

Outline the cause and treatment of Haws syndrome in the cat

A
  • Unknown, though to be associated with some kind of viral infection
  • Dysautonomia of some sort
  • Generally self limited and will spontaneously resolve
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11
Q

What is herpes keratitis of the feline eye?

A

Corneal condition caused by FHV-1

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12
Q

Describe the appearance of herpes keratitis in the feline eye

A
  • Pathognomic dendritis ulcers
  • Can recur (latent in trigeminal nerve)
  • Assocaited with KCS, entropion, symblepharon, occluded puncta
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13
Q

Outline the treatment of feline herpes keratitis

A
  • Trifluorothymidine, gancyclovir, interferon, oral lysine

- Famcyclovir oral is first choice of treatment

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14
Q

Describe the appearance of eosinophilic keratitis of the feline eye

A
  • Diffuse corneal oedema, vascularisation and plaques
  • Usually unilateral initially, often dorsolateral quadrant
  • Plaques/deposits on cornea/limbus/conjunctiva, bizarre whitish colour resembling cottage cheese
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15
Q

Describe the diagnosis of eosinophilic keratitis of the feline eye

A
  • Clinical signs

- Granulomatous inflammation on exfoliative cytology with eosinophils

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16
Q

Outline the treatment of eosinophilic keratitis in the feline eye

A

Usually responds to corticosteroids or cyclosporine but often difficult to treat and often recurs

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17
Q

Outline the cause of eosinophilic keratitis in the feline eye

A
  • May be a sign of autoimmune diseases within the cornea

- Not fully understood, associated with herpes but can also occur in itself

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18
Q

What is corneal sequestrum of the feline eye also known as?

A

Corneal necrosis

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19
Q

Outline the causes of feline corneal sequestrum

A
  • Unknown cause
  • Some breed-predisposition (e.g. Persians) and in non-pedigree cats after corneal insult
  • Some association with herpes
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20
Q

Describe the appearance of a feline corneal sequestrum

A
  • Range from ill-define tea stains of corneal stroma to clearly demarcated black plaques
  • Variable amount of neovascularisation
  • Ulceration associated with pain
  • Surface necrosis of superficial cornea
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21
Q

Outline the treatment of feline corneal sequestrum

A
  • Surgical removal of plaque if risk of rupture

- Plaques may slough and spontaneously resolve

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22
Q

What is meant by, and give examples of, primary ocular neoplasias in the cat?

A

Arise within the eye itself

  • Diffuse iris melanoma
  • Ciliary body adenocarcinoma
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23
Q

Give examples of neoplasias that may cause secondary effects in the eye

A
  • FeLV, lymphoma/lymphosarcoma

- Metastases

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24
Q

Describe the occurrence of diffuse iris melanomas

A
  • Mainly seen in cat

- In cats diffuse lesions, in dogs single lesion

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25
Q

Describe the appearance of diffuse iris melanomas in the cat

A
  • Generally pigmented
  • Can have premelanoma stages called melanosis where there are no neoplsatic cells present yet
  • Characteristic patchy dark pigmentation of iris surface, may change over time and become diffuse thickening changing iris to look abnormally thickened
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26
Q

Outline the treatment of diffuse iris melanoma in cats

A
  • Look at iris stroma/iris root (drainage angle) and ultrasound to assess if stroma is thickening
  • Can leave or be proactive
  • Ablation of iris to prevent tumour spread
  • Enucleation to prevent metastasis, even if eye is otherwise functional
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27
Q

Describe the ocular signs that may occur with lymphoma or leukaemia virus in cats

A
  • Change in colour, hyperaemia
  • Nodular appearance, with slit lamp see these as nodular thickenings
  • Ocular signs associated with severe lymphoreticular disease
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28
Q

Compare the occurence of cataracts in cats and dogs

A

Uncommon in cats vs dogs

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29
Q

List the potential causes of cataracts in the feline eye

A
  • CAn be inherited and present at different stages of life
  • Associated with intraocular inflammation
  • Inflammation e.g. uveitis
  • Encephalitozoon cuniculi
  • Post traumatic ocular sarcoma
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30
Q

Explain why E. cuniculi may cause cataracts in cats

A

Has tropism for the lens

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31
Q

Explain how trauma may lead to cataracts

A

Once lens is breached, have increased risk of tumour e.g. ocular sarcoma, forming later in life. Is specific to cats

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32
Q

Describe the presentation of anterior uveitis in cats

A
  • Insidious onset

- May see iris hyperaemia, iris nodules, keratitis precipitates

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33
Q

What are the main 4 causes implicated in uveitis in cats?

A
  • FeLV
  • FIV
  • FIP
  • Toxoplasmosis
    (idiopathic also common)
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34
Q

Outline the diagnosis of uveitis in the cat

A
  • Tests for the most common causes of uveitis
  • Ophthalmic examination
  • Blood profile
  • FeLV/FIV testing
  • Serology and PCR
  • Radiography and ultrasound
  • Cytology and histopathology
  • Referral to specialist
  • In most cases, ophthalmic exam, best guess diagnosis, empirical treatment and assessment of response to therapy form basis of diagnosis
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35
Q

What are keratitic precipitates in the feline eye?

A

Inflammatory products (WBCs etc) adhering to the cornea. Cause unknown. Aka mutton fat deposits

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36
Q

Describe the appearance of the normal feline retina

A
  • More uniform than dog, optic discs smaller and rounder, surrounded by pigment ring
  • No venous cricle
  • Generally 3 arterioles
  • Tapetum more uniformly greenish yellow
  • More vivid colour than dogs
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37
Q

Describe the appearance of the feline retina with taurine deficiency

A
  • Leads to retinal degeneration
  • Band-shaped lesion dorsal to optic disc horizontally
  • Progressing to generalised degeneration and blindness
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38
Q

Describe the appearance of choroidal metastases in the cat

A
  • Sight deficiency, optic nerve and vessels very abnormal, patchy hazy areas
  • Metastatic spread from pulmonary carcinoma
  • Forms thromboembolism
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39
Q

Discuss the importance of a retinal exam in older cats

A
  • retinal hypertension common in older cats, indicaive of disease
  • can lead to retinal detachment or retinal haemorrhaging
  • Often no particular signs until too late
  • Need to identify and treat the underlying condition
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40
Q

List the common causes of hypertension in geriatric cats

A
  • renal disease
  • Hyperthyroidism
  • Conn’s disease (tumour of adrenocortical gland leading to hyperaldosteronism)
  • Diabetes mellitus
  • Essential hypertension
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41
Q

Explain why the eye is vulnerable to systemic disease

A
  • Systemic blood supply

- Immunoprivilege

42
Q

List systemic diseases associated with uveitis in the dog

A
  • Infectious canine hepatitis
  • Leptospirosis
  • Brucellosis
  • Toxoplasmosis
  • Systemic mycoses
  • Leishmaniasis
  • Ehrlichiosis
  • Rickettsia
  • Ocular nematodes
  • Uveodermatological syyndrome
  • Lymphoma
  • Multiple myeloma
  • Metastases
  • immune mediated thrombocytopaenia
  • Blood dyscrasias
  • Hypertension
43
Q

Describe uveodermatological syndrome in the dog

A
  • Severe/acute/chronic skin change
  • Colour change
  • Autoimmune disease against melanin
  • Lots of melanocytes in the eye
  • Leads to inflammatory changes in the eye, can lead to blindness
  • Slow progression, can be slowed with treatment
  • Also called VKH, more common in akias
44
Q

List the systemic diseases associated with uveitis in the cat

A
  • Feline leukaemia virus
  • Immunodeficiency virus
  • Feline infectious peritonitis
  • Toxoplasmosis
  • Bartonea
  • Mycobacterium
  • Hyerptension
  • E. cuniculi
45
Q

List the systemic diseases associated with uveitis in the horse

A
  • Equine recurrent uveitis

- Leptospirosis

46
Q

List the systemic diseases associated with uveitis in cattle

A
  • Bacterial septicaemia
  • MCF
  • TB
  • Leptospriosis
  • Thromboembolic meningiencephalitis
  • Silage eye
47
Q

Describe the ocular manifestation of Angiostrongylus

A
  • Haematogenous spread

- Becomes antigenic focus of inflammation and infection in the eye, causing blindness

48
Q

Explain the formation and treatment of diabetic cataracts

A
  • Sugar accumulates in eye
  • Alternate pathways (AR pathway) followed, leads to accumulations of osmotic metabolites (sorbitol) that draw in water
  • Risk of lens rupture, need to remove cataracts
49
Q

Explain the formation of and describe the apperance and treatment of a lipid laden aqueous in the dog

A
  • Eyes become opaque overnight
  • White opalescent material in anterior chamber
  • Occurs due to hyperlipidaemic state and high TAGs in blood
  • Treat by starvation
50
Q

Explain how hypothyroidism can affect the eye

A
  • Corneal lipidosis
  • Accumulation of lipid in cornea, lipid laden aqueous
  • May have elevated cholesterol
  • Arcus formation can occur - lipid in cornea in bilateral ring shape and patchy
51
Q

What are the potential causes of calcareous degeneration in the eye?

A

Corneal calcification, can be due to extreme aging, renal disease or Cushing’s

52
Q

Describe a potential ocular manifestation of hypoparathyroidism

A

Cataracts unusual spotty appearance

53
Q

Describe the ocular manifestation of lymphoma

A
  • cellular deposits in anterior chamber
  • Iris swollen
  • Lymphadenopathy, hypercalcaemia and polydipsia commonly seen
54
Q

Explain how multiple myeloma may lead to ocular signs

A
  • Disseminate abnormal plasma cells

- Hypertension may occur due to hyperviscosity and hypergamaglobulinaemia of the blood

55
Q

Describe the ocular manifestation of systemic mycosis fungoides

A
  • Free blood in the eye
56
Q

What is mycosis fungoides?

A

Cutaneous lymphoma

57
Q

How does mycosis fungoides lead to ocular signs?

A

Coagulopathy leading to free blood seen (may also have skin crusting and fissuring, platelets are norma)

58
Q

Describe the ocular manifestation of malignant histiocytosis

A

Nodules of the eye

59
Q

Describe malignant histiocytosis

A
  • Proliferative inflammatory disease that becomes fatal

- Circulating histiocytes which in mild cases may cause only skin disease e.g. crusting or nodular lesions of skin

60
Q

Describe the development, apperance and treatment of uveal melanomas

A
  • Can be primary neoplasia of the eye or secondary as a metastasis
  • Distinct solid mass, slightly raised, will change
  • Benign gets bigger
  • Eye may need to be removed to prevent metastasis or due to discomfort
61
Q

List metastases of solid tumours that may cause ocular signs

A
  • Haemangiosarcoma
  • malignant melanoma
  • Iveal melanoma
  • Mammary adenocarcinoma
  • Angioinvasive pulmonary carcinoma in cats
62
Q

List diffuse tumours that may cause ocular signs

A
  • Lymphoma
  • Multiple myeloma
  • Mycosis fungoides
  • Malignant histiocytosis
63
Q

List endocrine conditions that may cause ocular signs

A
  • Diabetes
  • Hyperlipidaemia
  • Canine hypothyroidism
  • Hyperthryoidism
  • Cushing’s
  • Hypoparathryoidism
64
Q

Describe uveal cysts (prevalence, appearance)

A
  • Common, non-neoplastic

- Pigmented abnormalities, very spherical, semi-transparent

65
Q

Give examples of coagulopathies that can affect the eyes

A

Immune mediated thrombocytopaenia, coumarin toxicity

66
Q

Give examples of drug reactions that may affect the eyes

A
  • Sulphonamides exacerbate dry eye
  • Enrofloxacin induced blindness may occur in cats
  • Idiosyncratic drug eruptions
67
Q

Give examples of neurological conditions that may affect the eye

A
  • Chorioretinitis
  • Optic neuritis
  • Papilloedema
68
Q

Explain why neurological disease can manifest in the eye

A
  • Retina is a neurological tissue

- Clear layer with ganglion cells, myelinated in dog

69
Q

What is the common ocular manifestation of inflammatory meningitis?

A

Acute blindness

70
Q

Describe optic neuritis

A
  • Uncommon inflammatory condition of the optic nerve
  • If bilateral = acute blindness
  • No specific diagnosis until further investigation
71
Q

What are the common causes of optic neuritis in the dog?

A
  • Canine distemper

- GME

72
Q

What is papilloedema?

A

Oedema of the optic nerve without free blood

73
Q

Describe the ocular manifestation of immune mediated thrombocytopaenia

A
  • Eyes look full of blood
  • Sight tests show poor vision
  • Petechial haemorrhages of mucous membranes
  • Redness in eye may clear when rested and steroids
  • If blood clots, may get fibrin and glaucoma, leading to non-functional eye
74
Q

What are the common underlying causes of immune mediated thrombocytopaenia?

A

Primary or secnodary to neoplasia, or drugs

75
Q

List ophthalmic emergencies

A
  • Traumatic globe prolapse
  • Retrobulbar abscess
  • Acute glaucoma
  • Anterior lens luxation
  • Corneal emergencies
  • Sudden onset blindness
76
Q

Define an ophthalmic emergency

A

A condition that threatens vision and/or the globe itself and requires immediate action

77
Q

Compare what is meant by a globe prolapse and exophthalmos

A
  • Prolapse: globe acutely displaced forwards beyond the plane of the eyelids
  • Exophthalmos: degree of forward displacement of the globe with the eyelids remaining in their normal anatomical position
78
Q

Describe the pathophysiology of a globe prolapse

A
  • Immediate oedema of conjunctiva and orbital soft tissue, exacerbated by eyelid spasm preventin gvenous drainage and leading to further swelling
  • Traction on optic nerve likely to result in permanent blindness
  • Dessicationof ocular surface, corneal ulceration
79
Q

Discuss globe prolapse in brachycephalic breeds

A
  • Shallow orbits impart little protection for eye
  • Very little force required to cause prolapse e.g. scruffing
  • Easy o replace, better prognosis than for other breeds
80
Q

Discuss globe prolapse in cats

A
  • cats have deeper orbits and therefore better protection

- Large amount of force required for prolapse e.g .head trauma in RTA

81
Q

Describe the indications for the replacement or enucleation of a globe following prolapse

A
  • Generally attempt replacement if not sure, enucleation can be done later
  • Enucleation if soft tissue attachments are almost all severed of if optic nerve severed
82
Q

Outline the treatment of globe prolapses

A
  • Immediate treatment required
  • Analgesia
  • Faster treatment improves prognosis for vision and globe
  • Delay for referral usually inappropriate
  • Keep globe moist with wet swab, ointment
  • Prevent self-trauma with buster collar
  • Sedation
  • GA for replacement of globe once ensure there is no other trauma that precludes GA e.g. ruptured diaphragm
  • Systemic NSAIDs and antibiotics
  • Remove stitches in 10-14 days
83
Q

Outline the method for the replacement of a prolapsed globe

A
  • +/- clip hair: yes if prolapsed several hours, no if in last half hour (save time)
  • Prep with sterile saline or povidone iodine (no scrub, no alcohol)
  • Pull eyelids forwards using hooks, stay sutures or Allis tissue forceps (difficult in practice)
  • Lateral canthotomy to increase eyelid opening, reduces pressure on globe
  • After canthotomy, pull eyelids forwards, up and over globe with simultaneous pressure on globe via wet swab
  • Repair canthotomy, deep layer first then skin
  • Temporary tarsorrhaphy to protect eye and prevent re-prolapse
84
Q

Outline the method for a temporary tarsorrhaphy

A
  • Simple interrupted sutures, start 3-5mm away from eyelid margin
  • Needle can emerge from eyelid margin (preferred) or just behind
  • Use 5/0 vicryl, 3-4 sutures
  • Care not to penetrate conjunctiva
  • Sutures need to be tight as swelling will go down
  • Can also use horizontal mattress sutures, and use plastic tubing to reduce pressure from sutures on eyelid skin
85
Q

Explain the common appearance of the eye following prolapse

A
  • Medial rectus muscle almost always ruptures
  • Often leads to lateral strabismus
  • In almost all cases will return to normal ~4 weeks
86
Q

Discuss the prognosis of globe prolapses

A
  • Guarded, even with prompt, appropriate therapy
  • Majority of eyes are blind
  • Most owners prefer blind eye to no eye
  • Blind but pain-free globe is acceptable, blind but uncomfortable globe requires enucleation
87
Q

Describe the clinical signs of a retrobulbar abscess

A
  • Acute onset
  • Unilatral
  • Exophthalmos
  • Pain (esp on opening mouth)
  • ocular discharge
  • Third eyelid protrusion and swelling
  • Often pyrexic (inflammatory process)
88
Q

What are some potential causes of retrobulbar abscesses?

A
  • Idiopathic
  • Foreign body
  • Tooth root abscess
  • Many causes
89
Q

Describe the approach to a potential retrobulbar abscess

A
  • Urgent, but not as urgent as globe prolapse
  • Examine mouth, although pain may not allow this
  • Examine for entry wound or abscess that has come to head in mouth
  • Examine for signs of rotting teeth
90
Q

Describe the treatment of a retrobulbar abscess

A
  • Drain abscess under GA
  • Access to soft tissue floor of orbit via mouth
  • Scalpel incision, insert artery forceps blindly into retrobulbar space
  • Most eyes are 2cm from cornea to sclera, do not drape as need to be able to see eye in order to prevent puncture
  • Release pus, may collect for culture
  • Ultrasound can be used to visualise abscess but not usually used during procedure
91
Q

Outline the medical management of retrobulbar abscesses

A
  • Systemic NSAIDs
  • Systemic antibiotics
  • Topical lubricants until normal blinking returns
92
Q

Discuss the prognosis of a retrobulbar abscess

A
  • If pressure and traction on optic nerve can have temporary or permanent blindness if not treated fast enough
  • Prognosis generally good, usually resolve and don’t recur
  • Recurrence is possible, esp. if undiagnosed FB
93
Q

What is a potential outcome of acute glaucoma in the dog?

A

Can become irreversibly blind within 12 hours

94
Q

Describe the clinical signs of acute glaucoma

A
  • Increased lacrimation
  • Blepharospasm
  • Photophobia
  • +/- yelping, head shyness, dull/quiet (similar to migraine?)
  • Reduced vision or blindness
  • Blue eye due to corneal oedema when IOP >40mmHg (normal 15-25mmHg)
  • Episcleral congestion (conjunctival hyperaemia and involvement of deeper vessels)
  • Pupil dilation, fixed, no PLR
95
Q

Describe the diagnosis of acute glaucoma

A

Tonometry (normal is 15-25mmHg, often >40mmHg, possible to get 60-80mmHg)

96
Q

Describe the treatment of acute glaucoma

A
  • Reduce IOP, choice of drug depends on cause, PG analogue eye drops effective in dogs
  • Analgesia essential (carprofen, meloxicam)
  • Referral to ophthalmologist ASAP
97
Q

What are the 2 main groups likely to present with acute glaucoma?

A
  • Hereditary primary glaucoma in purebreeds e.g. spaniels, retrievers, Bassett hounds, Siberian husky
  • Terrier breeds with acute lens luxation and secondary glaucoma
98
Q

How does primary glaucoma of purebreeds occur?

A
  • Nothing wrong with eye, born with abnormal drainage angle

- Some trigger factor in middle age, unknown what this is

99
Q

What is the most likely diagnosis for a terrier with an acutely painful eye?

A

Lens luxatoin

100
Q

Describe lens luxation in terriers

A
  • Hereditary condition
  • Defect of lens zonules
  • In middle age, lens detaches, moves forwards and becomes wedged in anterior chamber and get rapid increase in pressure

NEU2 (23 decks)

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