Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

NEU2 > Small animal ophthalmology 3 > Flashcards

Small animal ophthalmology 3 Flashcards

Ophthalmic emergencies, ocular pharmacology

1
Q

Describe the treatment of anterior lens luxation

A
  • Surgical removal of lens
  • Commonly bilateral - other eye likely to be at subluxation rather than full but still affected
  • Analgesia required e.g. oral NSAID and opioid in short term
  • Referral for lens removal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Give examples of corneal emergencies

A
  • Chemical injury
  • Foreign body
  • Melting ulcer
  • Severe lacerations
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the treatment of chemical corneal injuries

A
  • Eyelid often also affected
  • Immediate irrigation: tap water, saline, Hartmann’s
  • Flush until pH normal (7.5), sedation likely to be necessary
  • seek early specialist advice
  • Medical management for corneal ulcers: alkalis may induce melting or liquefactive necrosis, intensive medical management indicated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What would constitute a corneal foreign body classing as an emergency?

A

Only if large and painful, urgent attention for all FBs, but most are not true emergencies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Outline the treatment of corneal foreign bodies

A
  • Sedate/GA
  • Local anaesthetic
  • Use magnification and remove FB (may need referral depending on depth)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Categories corneal ulcers as either urgent or true emergencies

A
  • Urgent: deep corneal ulcers, demetocoeles, perforated corneal ulcer, iris prolapse
  • Melting ulcers are true emergencies
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the potential response and outcome of the iris to a perforated corneal ulcer

A
  • Iris can come forward and plug perforation
  • May get plug of fibrin
  • Reduces pain
  • Can be left overnight if stable, treatment may require a graft
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Compare the prognosis for sharp vs blunt corneal trauma

A
  • Sharp: better prognosis

- blunt more likely to cause splitting of globe hich then requires removal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Identify the common causes of sudden onset blindness

A
  • Acute glaucoma
  • Acute uveitis
  • Intraocular haemorrhage
  • Retinal detachment
  • Optic neuritis
  • Sudden Acquired Retinal Degeneration (SARD)
  • Toxicity (ivermectin, enrofloxacin in cats)
  • Intracranial lesion e.g. tumour
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Discuss the use of steroids in the treatment of sudden onset blindness

A
  • IN some, will prevent blindness, in others no difference

- e.g. optic neuritis steroids good, in SARD steroids no use - irreversible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

In a case of sudden onset blindness with no visible abnormalities in the eye, what are the most likely differentials and how will you diagnose the cause?

A
  • Optic neuritis
  • SARD
  • Toxicity
  • Intracranial lesion
  • ERG (electroretinogram) or MRI for diagnosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe ophthlamic drops (formulation, duration of action, application)

A
  • Can be solutions, suspensions, emulsions
  • Short duration of action
  • High frequency of application
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe ophthalmic gels (formulation, duration of action, application)

A
  • Liquefy on contact with ocular surface
  • Longer duration of action
  • Easy to apply
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe ophthalmic ointments (formulation, duration of action, application)

A
  • Paraffin-based/lanolin based
  • Prolonged corneal contact
  • Low frequency of adminstration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Compare and explain the importance of the delivery volume and retained volume of eye drops

A
  • Delivered: 50ul, retained: 20ul
  • Only give 1 drop at a time
  • > 1 drop stimulates reflex tearing and dilution effect
  • Allow 10-15mins between administration of different topical drugs and apply longer acting drugs last
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

List common topical antibacterial drugs for ophthalmic use

A
  • Fusidic acid
  • Chloramphenicol
  • Fluoroquinolones
  • Aminoglycosides
  • Cloxacillin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Against which agents is fusidic acid effective?

A
  • Good G+ve acitivity, esp. Staph

- Poor vs Chlamydophila felia, Pseudomonas spp.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe the main advantages of topical fusidic acid for ophthalmic use

A
  • Good corneal penetration
  • Gel/drop formulation, easy to use
  • Once daily dosing, good owner compliance
  • Licensed (Isathal)
  • Good first line topical for minor ocular surface infections e.g. conjunctivitis, minor superficial ulcers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the activity of topical ophthalmic chloramphenicol

A
  • Broad spec, incl, anaerobes

- Poor vs. Chlamydophila felis, Pseudomonas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe the main advantages of topical ophthalmic chloramphenicol

A
  • Good corneal penetration
  • Good for ocular surface disease esp. in dogs, ocular surgery, penetrating corneal trauma
  • Low toxicity to corneal epithelium, therefore good for corneal ulcers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Describe the activity of topical ophthalmic fluoroquinolones

A
  • Broad spec
  • Effective against G-ve and some G+ve
  • some Staph and Strep species may be resistant
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Give examples and evaluate the use of topical ophthalmic fluoroquinolones

A
  • Ofloxacin, ciprofloxacin
  • Are not first choice, used following culture and sensitivity or if presenting signs are very serious e.g. melting ulcer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Describe the activity of topical ophthalmic aminoglycosides

A
  • Effective against G-ve and some aerobic G+ve incl. Staph spp.
  • Effective against Pseudomonas
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Give examples of and Evaluate the use of topical ophthalmic aminoglycosides

A
  • Neomycin and gentamycin
  • Gentamycin (clinagel, tiacil) historically for suspected Pseudomonas, epitheliotoxic to corneal epithelium, offten irritant, superseded by others
  • Neomycin often in combination with topical steroid (maxitrol) drops/ointments) can cause irritancy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Describe the activity of topical ophthalmic cloxacillin

A

Bactericidal to beta-lactamase-resisant penicillin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Evaluate the use of topical ophthalmic cloxacillin

A
  • Orbenin
  • Topical antibiotic routinely used for IBK, readily available
  • Ideally would use single long acting oxytet injection for IBK but very expensive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Describe the method and advantages of subconjunctival antibiotic injections

A
  • Injection of drug under bulbar conjunciva
  • Slow release of drug, reduces labour intensity of treatment
  • Can be used with any drug
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the most common use of subconjunctival antibiotic injections?

A

Penicillin g in the treatment of IBK

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

List the common systemic antibiotics used in the treatment of ophthalmic conditions

A
  • Clindamycin
  • Tetracyclines
  • Sulphonamides
  • Enrofloxacin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Describe the action of and main use for systemic clindamycin in ophthalmology

A
  • Macrolide antibiotic, bacteriostatis

- Effective against Toxoplasma gondii e.g. Antirobe, Cleocin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Give examples of, and pros and cons of systemic tetracyclines in ophthalmology

A
  • Doxycyline (ronaxan), oxytetracycline
  • Doxy is treatment of choice for feline chlamydial infection 3 week course can eradicate)
  • Can discolour teeth in young animals, not for use in pregnant queens
  • Can cause oesophagitis, essential to give with water/food
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Evaluate the use of systemic sulphonamides in ophthalmology

A
  • Can cause KCS due to toxic effect on lacrimal gland in some dogs
  • May or may not be reversible depending on severity of effect on gland
  • Less frequently used now
  • Monitor STT at start of treatment and weekly while on treatment
  • Horses unaffected by dry eye as a consequence
33
Q

Discuss the use of systemic enrofloxacin in the treatment of ophthalmic disease in cats

A
  • Contraindicated, very narrow therapeutic index in cats
  • can cause permanent blindness due to retinal toxicity, not dose dependent
  • Risk of blindness does not apply to all fluoroquinolones e.g. marbofloxacin is safe at routine doses in cats
34
Q

Outline the use of ophthalmic antifungals

A
  • No commercially available topical preparations
  • Equine keratomycosis more common than canine
  • Seek specialist advice
35
Q

Describe the topical ophthalmic antivirals available in the UK

A
  • Ganciclovir 0.15% (Zirgan): can be used in cats with herpes
  • Aciclovir 3% ointment (Zovirax): OTT, 5x daily, efficacy unsure
36
Q

Describe the oral anti-viral treatments for ophthalmic conditions in the UK

A
  • Famciclovir tablets
  • Expensive, but generic now available
  • Reserved for severe/persisting herpes with clinical signs
  • Recommended dose varies frequently because of ongoing research (currently 90mg/kg BID)
37
Q

What are the indications for the use of anti-inflammatory drugs in ophthalmology?

A
  • Immune mediated disease
  • Extraocular: KCS, feline eosinophilic keraticonjunctivitis, chronic superficial keratitis (pannus)
  • Intraocular: uveitis
38
Q

Explain the contraindications for the use of topical ophthalmic steroids

A

Corneal ulceration in all species, as steroids exacerbate collagenolysis leading to corneal perforation (NB can use systemic steroids with ulcers if needed)

39
Q

What are the main topical steroid options for ophthalmic use?

A
  • Dexamethasone phosphate
  • Prednisolone acetate
  • Combinations with antibiotics
40
Q

Give the main indication for and penetrative ability of dexamethasone phosphate in the eye

A
  • Good for ocular surface disease e.g. pannus
  • Poor penetration into cornea
  • e.g. Maxidex
41
Q

Give the main indication for and penetrative ability of prednisolone acetate in the eye

A
  • Good for intraocular disease e.g. uveitis
  • Good corneal penetration
  • E.g. Predforte
42
Q

What are topical NSAIDs used for in ophthalmology?

A

Uveitis and intraocular surgery

43
Q

Discuss the use of topical NSAIDs in ophthalmology

A
  • Epitheliotoxic and delay healing of corneal ulcers, but not as bad as topical steroids
  • Ketorolac trometamol = acute, most common in general practice
  • Flurbiprofen
  • Better to use systemic NSAID
44
Q

Discuss the use of ciclosporine in the treatment of ophthalmic conditions

A
  • T cell suppression, inihibits IL-2
  • Increases tear production (mainstay of KCS management)
  • Anti-inflammatory action: reduces scar tissue on ocular surface (corneal pigmentation and vascularisation)
  • Safe to use with corneal ulceration (even if dry eye ulcer present)
  • Poor corneal penetration, ocular surface disease only
45
Q

Discuss the use of immunomodulatory drugs used in ophthalmology

A
  • Calcinuerin inhibitors, reduce T lymphcyte activation
  • Address immune mediated destruction of lacrimal tissue
  • Ciclosporin (Optimmune) licensed
46
Q

What are the mechanisms of action of anti-glaucoma drugs?

A
  • Reduce aqueous humour production

- OR increase aqueous humour outflow

47
Q

List anti-glaucoma drugs used in veterinary

A
  • Carbonic anhydrase inhibitors e.g. dorzolamide, brinzolamide
  • Adrenergic agents e.g. tomolol maleate
  • Prostaglandin analogues
  • Osmotic diuretics e.g. mannitol
48
Q

Describe the mechanism of action of carbonic anhydrase inhibitors in the treatment of glaucoma

A
  • Carbonic anhydrase catalyses reaction in ciliary bodies to form aqueous humour
  • CAIs inhibithis and reduce formation of humour, which leads to reduction in IOP
49
Q

Compare topical and systemic carbonic anhydrase inhibitors for glaucoma

A

Topical superseded systemic formulations due to fewer side effects

50
Q

Outline the use of dorzolamide (CAI) in the treatment of glaucoma

A
  • Trusopt
  • Effective in dogs and cats
  • q6-8hrs
  • Can combine with other anti-glaucoma drugs with different modes of action
  • Little reduction in pressure, poor for emergency glaucoma cases
51
Q

Outline the use of brinzolamide (CAI) in the treatment of glaucoma

A
  • Azopt
  • Effective in dogs, not cats
  • q6-8hrs
  • Can combine with other drugs
  • Better tolerated vs dorzolamide due to more neutral pH
  • 1st choice in` dogs
52
Q

Describe the mechanism of action of adrenergic agents for the treatment of glaucoma

A
  • Beta blockers

- Reduce production of aqueous humour

53
Q

Evaluate and give an example of the use of adrenergic agents in the treatment of glaucoma

A
  • Can cause mild miosis
  • Can cause bradycardia (care in small patients with heart disease and/or asthma)
  • Little reduction in pressure
  • Tomolol maleate 0.5% (Timoptol)
54
Q

Describe the mechanism of action of prostaglandin analogues in the treatment of glaucoma

A

PGF2a in low concentrations increases aqueous outflow if in very dilute form

55
Q

Discuss the use of prostaglandin analogues in the treatment of glaucoma and give examples of drugs

A
  • Very effective in dogs, ineffective in cats
  • reduces IOP to safe level within 60-90 min of single application
  • Applied 1-2 times daily
  • Intense miosis follows use
  • Contraindicated in uveitis and anterior lens luxation
  • 0.005% latanoprost (Xalatan) or generic form 0.004% Travoprost (Travatan)
56
Q

Explain why prostaglandin analogues are contraindicated in uveitis and anterior lens luxation

A
  • Due to effects on pupil - don’t want to make pupil any smaller than it already is in uveitis, painful
  • Within lens luxation, further pupil constriction can cause lens to become trapped in anterior chamber
57
Q

Describe how osmotic diuretics work in the treatment of glaucoma

A

Make volume of vitreous shrink, lens moves back, opens up drainage angle

58
Q

Evaluate the use of osmotic diuretics in the treatment of glaucoma and give an example

A
  • mannitol IV over 30 mins
  • Reduces IOP within 1 hour, can last for up to 24 hours
  • Causes osmotic diuresis and dehydration so monitor hydration and electrolytes
  • Check renal and cardiac function before use
  • Now infrequently used
59
Q

What is the action of mydriatics and what are their uses?

A
  • Dilate the pupil
  • For diagnostics: examine lens, fundus, use short acting agent
  • Therapuetic: intraocular surgery, uveitis, long acting agent
60
Q

What is the action of cycloplegics in ophthalmology and what are their uses?

A
  • Relax ciliary body musculature
  • Relieve painful ciliary spasm associated with anterior uveitis
  • Therapeutics only
61
Q

Describe the use of tropicamine in ophthalmology

A
  • Parasympatholytic
  • Mydriatic&raquo_space;cycloplegic effect
  • rapid onset (30 mins), short duration (8-12 hours)
  • Main use is diagnostic purposes
62
Q

Describe the use of atropine in ophthalmoloyg

A
  • Parasympatholytic
  • Mydriatic and cycloplegic effects
  • Slow onset (60 min), long duration (60-129)
  • Main use for therapeutics
63
Q

Outline the side effects and systemic effects of atropine

A
  • Side: reduces tear production, care in animals with dry eye and brachycephalics, raises IOP, contraindicated in glaucoma
  • Systemic: hypersalivation due to bitter taste when travels down tear ducts, tachycardia, constipation (uncommon but care if low bodyweight), care re. colic in horses, monitor gut sounds but use commonly in horses
64
Q

Describe the 3 types of lacrimomimetics

A
  • Aqueous layer: aqueous drops
  • Mucin layer: mucinomimetics (gels)
  • Lipid layer: lipid based ointments (mineral oil, lanoliin, petrolatum)
65
Q

Describe the typical order in which ophthalmic preparations should be applied

A
  • Drops first
  • Then gel
  • Then ointment
66
Q

Describe the use of drop formulation aqueous tear substitutes (examples, period of activity, administration, uses)

A
  • Methyl cellulose, polyvinyl alcohol
  • Short acting <20mins
  • High freq. of administration
  • Canine KCS generally too severe for these to useful
  • Good for flushing thick ocular discharge from affected dry eyes
67
Q

What are mucinomimetics made up of?

A
  • Linear polymers (dextran, polyacrylic acid, polyvinylpyrrolidone)
  • Carbomer 980 gels common
  • Viscoelastics (hyaluron derivative)
68
Q

Describe the use of mucinomimetics (examples, period of activity, administration, uses)

A
  • May be combined with aqueous substitutes
  • Medium duration (4-6hours)
  • 2-6 times daily admin depending on severity of problem
  • Viscotears, Lubrithal (licensed animal prod.), Remend
69
Q

Briefly outline Remend

A
  • Newer product
  • Remend corneal repair gel or Remend lubricating eye drop
  • 0.4-0.75% cross linked hyaluronic acid
  • Needs to be used in combination with antibiotics for ulcers
  • Is not a cure
70
Q

Describe the action of lipid based tear substitutes

A
  • Lanolin, petrolatum, mineral oil

- Prevent evaporation of tear film

71
Q

Describe the use of lipid based tear substitutes (examples, period of activity, administration, uses)

A
  • Lacrilube, VitAPos
  • Long acting (8-12hours), good corneal retention
  • 1-4 times daily
  • Blur vision, harder to apply for some owners
  • Good for protection during GA and for dry eye management e.g. last thing at night
72
Q

What are topical local anaesthetics used for in ophthalmology?

A
  • Diagnostic procedures e.g. tonometry, ocular ultrasound

- Minor surgical procedures e.g biopsy of conjunctiva

73
Q

What are injectable local anaesthetics used for in ophthalmology?

A
  • Periorbital nerve blocks in horses

- Orbital anaesthesia for enucleation

74
Q

Describe the use of topical local anaesthetics in ophthalmology (examples, period of activity, administration, contraindications)

A
  • Proxymetacaine (proparacaine)
  • Acts in 15seconds
  • lasts 30 mins
  • repeat application beneficial: 2-3 drops over 2-3 mins, increases depth and duration of anaesthesia
  • Cannot be used therapeutically as is epitheliotoxic and delays corneal healign
  • Do not apply before STT as will block reflex tear production
75
Q

Describe the use of injectable local anaesthetics in ophthalmology (examples, period of activity, administration, uses)

A
  • Lignocaine (lidocaine 1-2%) acts in 10 mins, lasts 60 mins
  • Bupivicaine (0.25-0.75%) acts in 45 mins and lasts for 6 hours, good for post-operative analgesia
  • Typically use both (lignocaine and bupivicaine 1-3 ml in 1:4 ratio) for enucleation to provide good peri and post-operative analgesia
76
Q

When performing cherry eye surgery, what is an important consideration regarding the application of phenylephrine?

A

Must be applied before any incisions are made, as accidental venous or arterial introduction would lead to unwanted systemic signs

77
Q

Discuss the formation of cysts following surgery for the correction of cherry eye

A
  • Cyst typically forms several weeks after surgery
  • Presents as non-painful swelling of the the TEL
  • Often misinterpreted as re-prolapse of the gland
  • Can be surgically excised intact with a good cosmetic result
78
Q

List common complications following the pocket technique for the correction of cherry eye

A
  • Re-prolapse
  • Cyst formation
  • Suture reaction
  • Corneal ulceration as a result of exposed suture material contacting ocular surface
  • Reduce mobility of the TEL
79
Q

Describe the appearance of generalised progressive retinal atrophy

A
  • Thin retinal blood vessels (vascular attentuation)
  • Tapetal hyper reflectivity
  • Pale optic disc/optic nerve head
  • May progress to irreversible blindness
  • Deteriorating sight (loss of night vision before day vision) and cloudy eyes

NEU2 (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions