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
2
Q
Describe neonatal ophthalmia in cats
A
Conjunctivitis beneath eyelid before eyes open (i.e. before 10-12 days)
3
Q
What are common causes of conjunctivitis in the feline eye
A
- Feline herpes virus
- Calicivirus
- Chlamydia felis
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
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
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
7
Q
Outline the treatment of lipogranulomatous conjunctivits in the cat
A
May need surgery to control if leads to irritation
8
Q
What is Haws syndrome of the cat?
A
Haws = third eyelid
Haws syndrome is prolapse of the third eyelid
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
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
11
Q
What is herpes keratitis of the feline eye?
A
Corneal condition caused by FHV-1
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
13
Q
Outline the treatment of feline herpes keratitis
A
- Trifluorothymidine, gancyclovir, interferon, oral lysine
- Famcyclovir oral is first choice of treatment
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
15
Q
Describe the diagnosis of eosinophilic keratitis of the feline eye
A
- Clinical signs
- Granulomatous inflammation on exfoliative cytology with eosinophils
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
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
18
Q
What is corneal sequestrum of the feline eye also known as?
A
Corneal necrosis
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
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
21
Q
Outline the treatment of feline corneal sequestrum
A
- Surgical removal of plaque if risk of rupture
- Plaques may slough and spontaneously resolve
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
23
Q
Give examples of neoplasias that may cause secondary effects in the eye
A
- FeLV, lymphoma/lymphosarcoma
- Metastases
24
Q
Describe the occurrence of diffuse iris melanomas
A
- Mainly seen in cat
- In cats diffuse lesions, in dogs single lesion
25
Describe the appearance of diffuse iris melanomas in the cat
- 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
26
Outline the treatment of diffuse iris melanoma in cats
- 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
27
Describe the ocular signs that may occur with lymphoma or leukaemia virus in cats
- Change in colour, hyperaemia
- Nodular appearance, with slit lamp see these as nodular thickenings
- Ocular signs associated with severe lymphoreticular disease
28
Compare the occurence of cataracts in cats and dogs
Uncommon in cats vs dogs
29
List the potential causes of cataracts in the feline eye
- CAn be inherited and present at different stages of life
- Associated with intraocular inflammation
- Inflammation e.g. uveitis
- Encephalitozoon cuniculi
- Post traumatic ocular sarcoma
30
Explain why E. cuniculi may cause cataracts in cats
Has tropism for the lens
31
Explain how trauma may lead to cataracts
Once lens is breached, have increased risk of tumour e.g. ocular sarcoma, forming later in life. Is specific to cats
32
Describe the presentation of anterior uveitis in cats
- Insidious onset
| - May see iris hyperaemia, iris nodules, keratitis precipitates
33
What are the main 4 causes implicated in uveitis in cats?
- FeLV
- FIV
- FIP
- Toxoplasmosis
(idiopathic also common)
34
Outline the diagnosis of uveitis in the cat
- 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
35
What are keratitic precipitates in the feline eye?
Inflammatory products (WBCs etc) adhering to the cornea. Cause unknown. Aka mutton fat deposits
36
Describe the appearance of the normal feline retina
- 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
37
Describe the appearance of the feline retina with taurine deficiency
- Leads to retinal degeneration
- Band-shaped lesion dorsal to optic disc horizontally
- Progressing to generalised degeneration and blindness
38
Describe the appearance of choroidal metastases in the cat
- Sight deficiency, optic nerve and vessels very abnormal, patchy hazy areas
- Metastatic spread from pulmonary carcinoma
- Forms thromboembolism
39
Discuss the importance of a retinal exam in older cats
- 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
40
List the common causes of hypertension in geriatric cats
- renal disease
- Hyperthyroidism
- Conn's disease (tumour of adrenocortical gland leading to hyperaldosteronism)
- Diabetes mellitus
- Essential hypertension
41
Explain why the eye is vulnerable to systemic disease
- Systemic blood supply
| - Immunoprivilege
42
List systemic diseases associated with uveitis in the dog
- 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
Describe uveodermatological syndrome in the dog
- 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
List the systemic diseases associated with uveitis in the cat
- Feline leukaemia virus
- Immunodeficiency virus
- Feline infectious peritonitis
- Toxoplasmosis
- Bartonea
- Mycobacterium
- Hyerptension
- E. cuniculi
45
List the systemic diseases associated with uveitis in the horse
- Equine recurrent uveitis
| - Leptospirosis
46
List the systemic diseases associated with uveitis in cattle
- Bacterial septicaemia
- MCF
- TB
- Leptospriosis
- Thromboembolic meningiencephalitis
- Silage eye
47
Describe the ocular manifestation of Angiostrongylus
- Haematogenous spread
| - Becomes antigenic focus of inflammation and infection in the eye, causing blindness
48
Explain the formation and treatment of diabetic cataracts
- 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
Explain the formation of and describe the apperance and treatment of a lipid laden aqueous in the dog
- Eyes become opaque overnight
- White opalescent material in anterior chamber
- Occurs due to hyperlipidaemic state and high TAGs in blood
- Treat by starvation
50
Explain how hypothyroidism can affect the eye
- 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
What are the potential causes of calcareous degeneration in the eye?
Corneal calcification, can be due to extreme aging, renal disease or Cushing's
52
Describe a potential ocular manifestation of hypoparathyroidism
Cataracts unusual spotty appearance
53
Describe the ocular manifestation of lymphoma
- cellular deposits in anterior chamber
- Iris swollen
- Lymphadenopathy, hypercalcaemia and polydipsia commonly seen
54
Explain how multiple myeloma may lead to ocular signs
- Disseminate abnormal plasma cells
| - Hypertension may occur due to hyperviscosity and hypergamaglobulinaemia of the blood
55
Describe the ocular manifestation of systemic mycosis fungoides
- Free blood in the eye
56
What is mycosis fungoides?
Cutaneous lymphoma
57
How does mycosis fungoides lead to ocular signs?
Coagulopathy leading to free blood seen (may also have skin crusting and fissuring, platelets are norma)
58
Describe the ocular manifestation of malignant histiocytosis
Nodules of the eye
59
Describe malignant histiocytosis
- 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
Describe the development, apperance and treatment of uveal melanomas
- 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
List metastases of solid tumours that may cause ocular signs
- Haemangiosarcoma
- malignant melanoma
- Iveal melanoma
- Mammary adenocarcinoma
- Angioinvasive pulmonary carcinoma in cats
62
List diffuse tumours that may cause ocular signs
- Lymphoma
- Multiple myeloma
- Mycosis fungoides
- Malignant histiocytosis
63
List endocrine conditions that may cause ocular signs
- Diabetes
- Hyperlipidaemia
- Canine hypothyroidism
- Hyperthryoidism
- Cushing's
- Hypoparathryoidism
64
Describe uveal cysts (prevalence, appearance)
- Common, non-neoplastic
| - Pigmented abnormalities, very spherical, semi-transparent
65
Give examples of coagulopathies that can affect the eyes
Immune mediated thrombocytopaenia, coumarin toxicity
66
Give examples of drug reactions that may affect the eyes
- Sulphonamides exacerbate dry eye
- Enrofloxacin induced blindness may occur in cats
- Idiosyncratic drug eruptions
67
Give examples of neurological conditions that may affect the eye
- Chorioretinitis
- Optic neuritis
- Papilloedema
68
Explain why neurological disease can manifest in the eye
- Retina is a neurological tissue
| - Clear layer with ganglion cells, myelinated in dog
69
What is the common ocular manifestation of inflammatory meningitis?
Acute blindness
70
Describe optic neuritis
- Uncommon inflammatory condition of the optic nerve
- If bilateral = acute blindness
- No specific diagnosis until further investigation
71
What are the common causes of optic neuritis in the dog?
- Canine distemper
| - GME
72
What is papilloedema?
Oedema of the optic nerve without free blood
73
Describe the ocular manifestation of immune mediated thrombocytopaenia
- 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
What are the common underlying causes of immune mediated thrombocytopaenia?
Primary or secnodary to neoplasia, or drugs
75
List ophthalmic emergencies
- Traumatic globe prolapse
- Retrobulbar abscess
- Acute glaucoma
- Anterior lens luxation
- Corneal emergencies
- Sudden onset blindness
76
Define an ophthalmic emergency
A condition that threatens vision and/or the globe itself and requires immediate action
77
Compare what is meant by a globe prolapse and exophthalmos
- 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
Describe the pathophysiology of a globe prolapse
- 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
Discuss globe prolapse in brachycephalic breeds
- 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
Discuss globe prolapse in cats
- cats have deeper orbits and therefore better protection
| - Large amount of force required for prolapse e.g .head trauma in RTA
81
Describe the indications for the replacement or enucleation of a globe following prolapse
- 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
Outline the treatment of globe prolapses
- 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
Outline the method for the replacement of a prolapsed globe
- +/- 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
Outline the method for a temporary tarsorrhaphy
- 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
Explain the common appearance of the eye following prolapse
- Medial rectus muscle almost always ruptures
- Often leads to lateral strabismus
- In almost all cases will return to normal ~4 weeks
86
Discuss the prognosis of globe prolapses
- 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
Describe the clinical signs of a retrobulbar abscess
- Acute onset
- Unilatral
- Exophthalmos
- Pain (esp on opening mouth)
- ocular discharge
- Third eyelid protrusion and swelling
- Often pyrexic (inflammatory process)
88
What are some potential causes of retrobulbar abscesses?
- Idiopathic
- Foreign body
- Tooth root abscess
- Many causes
89
Describe the approach to a potential retrobulbar abscess
- 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
Describe the treatment of a retrobulbar abscess
- 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
Outline the medical management of retrobulbar abscesses
- Systemic NSAIDs
- Systemic antibiotics
- Topical lubricants until normal blinking returns
92
Discuss the prognosis of a retrobulbar abscess
- 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
What is a potential outcome of acute glaucoma in the dog?
Can become irreversibly blind within 12 hours
94
Describe the clinical signs of acute glaucoma
- 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
Describe the diagnosis of acute glaucoma
Tonometry (normal is 15-25mmHg, often >40mmHg, possible to get 60-80mmHg)
96
Describe the treatment of acute glaucoma
- Reduce IOP, choice of drug depends on cause, PG analogue eye drops effective in dogs
- Analgesia essential (carprofen, meloxicam)
- Referral to ophthalmologist ASAP
97
What are the 2 main groups likely to present with acute glaucoma?
- Hereditary primary glaucoma in purebreeds e.g. spaniels, retrievers, Bassett hounds, Siberian husky
- Terrier breeds with acute lens luxation and secondary glaucoma
98
How does primary glaucoma of purebreeds occur?
- Nothing wrong with eye, born with abnormal drainage angle
| - Some trigger factor in middle age, unknown what this is
99
What is the most likely diagnosis for a terrier with an acutely painful eye?
Lens luxatoin
100
Describe lens luxation in terriers
- 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
