Ocular Emergencies Flashcards
Define emergency
Unexpected event that requires immediate action
Define ocular emergency
Condition that threatens vision and/or the globe itself
Define globe prolapse
Globe is acutely displaced forwards beyond the plane of the eyelids
Define exophthalmos
A degree of forward displacement of the globe with the eyelids remaining in a normal anatomical position
What is the pahophysiology of a globe prolapse?
- Immediate oedema of conjunctiva and orbital soft tissue, exacerbated by the eyelid spasm (venous drainage obstructed, further swelling …etc)
- Traction on optic nerve likely to result in permanent blindness
- Desiccation of ocular surface, corneal ulceration
Discuss globe prolapses in brachycphalic breeds
- Shallow orbits impart very little protection for eye
- Very little force required to cause prolapse
- Easy to replace, better prognosis
- Scruffing the animal can cause the eyes to prolapse
Discuss globe prolapses in cats
•Cats have deeper orbits and therefore better protection
–Large amount of force required to prolapse globe
–Head trauma in an RTA
Should we replace the globe?
Attempt replacement if not sure; enucleation can be done later
•If attachments are almost all severed, or if optic nerve severed, enucleate immediately
How do we treat a globe prolapse?
- IMMEDIATE TREATMENT indicated
- Pain
- Distressing to animal and owner
- Improves prognosis for vision and globe
- Delay for referral usually inappropriate
- This condition needs to be dealt with asap by YOU!
- Keep globe moist
–Wet swab, ointment (if animal lets you)
- Prevent self-trauma with Buster collar
- Sedation/analgesia
- GA for replacement of globe
How do you replace a globe prolapse?
•Pull eyelids forward
–hooks, stay sutures, Allis tissue forceps
•+/- lateral canthotomy
–cut skin at lateral canthus to make eyelid opening larger
–reduces pressure on globe
- Happened within half hour – get on with it
- Long time ago – clip hair
- Clean area
- Gentle pressure with wet swab on globe to push back into orbit
- Repair canthotomy
- Suture eyelids together (temporary tarsorrhaphy)
–Prevents re-prolapse
–Tamponades haematoma and oedema within orbit
- Systemic NSAIDS, antibiotics
- Remove stitches in 10-14 days
What does this show?
Lateral canthotomy
Discuss how you would complete a tarsorrhaphy?
- Simple interrupted sutures
- Start 3-5mm away from eyelid margin
- Needle can emerge from eyelid margin (preferred) or (just behind)
- 5/0 Vicryl
- 3-4 sutures
- Horizontal mattress sutures
- Plastic tubing to reduce pressure on eyelid skin
- Suture material must not go full thickness through eyelid – will rub on cornea and cause pain and ulceration
What is the issue here?
Stitches have been put too deep
What is the prognosis for a globe prolapse?
- Guarded, even with prompt, appropriate treatment
- Majority of eyes are blind (80% dogs, ?all cats)
- Most owners prefer a blind eye to no eye
- Blind but pain-free globe is acceptable
- Blind but uncomfortable globe may require enucleation later…
What causes a retrobulbar abscess?
Abscess or cellulitis behind the globe
What are the clinical signs of a retrobulbar abcess?
–Acute onset
–Unilateral (usually)
–Exophthalmos (proptosis)
–Pain, especially on opening the mouth
–Third eyelid protrusion and swelling
- Ocular discharge
How can you treat a retrobulbar abscess?
•Drain abscess under GA
–Sometimes cellulitis so nothing got drain
–Might want to image first – U/S CT best
- Access to soft tissue floor of orbit via mouth
- Scalpel incision, insert artery forceps blindly into retrobulbar space
- Recall that most eyes are 2cm from cornea to sclera
- Release pus…
- Hard to go into the eye as the eye is pushed forwards!
–Wouldn’t need to do this proecedure unless this was the case anyway
What is this?
Retrobulbar abscess
What is the issue of a retrobulbar abscess?
•Pressure around and traction on optic nerve can cause temporary blindness and, if not treated urgently, permanent blindness
What is the medical management of a retrobulbar abscess?
–Systemic NSAIDS
–Systemic antibiotics
–Topical lubricants until normal blinking returns
What causes acute glaucoma?
Acute rise in intraocular pressure
What are the clinical signs of acute glaucoma?
•Pain
–Classic triad of ocular pain
1) Increased lacrimation
2) Blepharospasm - closing eye
3) Photophobia - avoiding bright light
–Yelping, head shyness, dull/quiet (behaviour as though has a migraine)
–Go to bed and don’t want to move – imagine migraine
•Reduced vision or blindness
–Usually happens in one eye at a time though
•Change in appearance of eye…
What is blue eye?
Cornea oedema with IOP >40mmHg
What is this?
Red eye - Episcleral congestion
What will be missing with a dilated pupil?
PLR
How do you diagnose acute glaucoma?
- Tonometry
- Normal range in dogs and cats
–15-25mmHg
•Often >40mmHg
–Corneal oedema (‘blue eye’ typically develops when IOP >40)
•Possible to get IOPs of 60-80mmHg
How do you treat acute glaucoma?
•Reduce IOP – ASAP!!!!!!
–Choice of anti-glaucoma drug depends on cause of acute glaucoma
–Prostaglandin analogue (eye drop form) effective in dogs
•Analgesia – essential
–Anti-inflammatories e.g. meloxicam
–Opioids
•Ideally, referral to an ophthalmologist asap
Who is predisposed for acute glaucoma?
1.Hereditary primary glaucoma in purebreed dogs (e.g. spaniels, retrievers, basset hound, Siberian husky)
•Normal throughout life. Trigger factor 5-9 yo (unknown what) suddenly get it. Abnormal drainage angle!!!
2.Terrier breeds with acute lens luxation and secondary glaucoma
•Cross terriers too! Can get primary too
What happens with an anterior lens luxation?
Lens obstructs flow of aqueous through pupil causing… Increased IOP
Which breed do you suspect to have a anterior lens luxation?
Terrier
What is this?
Anterior lens luxation
Name some corneal emergencies
- Chemical injury
- FB
- Melting ulcer
- Severe lacerations
How do you treat chemical injuries?
•IMMEDIATE irrigation of ocular surface
–If at home, tap water is fine
–Tap water or saline or Hartmann’s solution if animal in the practice
•Tap water is better
–Flush copiously e.g. 500ml to 1 litre until pH normal (7.5); sedation likely to be necessary
•Test pH of conjunctival sac to determine nature of chemical e.g. urine dipstick
–Flush eye first
–Helps with prognosis – alkali injury is worse! Although you should be able to get this from history
- Early specialist advice
- Medical management for corneal ulceration
–Alkalis may induce ‘melting’ or liquefactive necrosis, intensive medical management indicated
Which of these is the only true emergency?
–Deep corneal ulcers
–Descemetocoeles
–Perforated corneal ulcer
–Iris prolapse
- ‘Melting’ ulcer
Melting ulcer
Discuss this
Perforated corneal ulcer with
iris involvement
Eye perforates – pain! Eye creates clot of aques and fibrin stabilies the eye but needs surgery
What is this?
‘Melting’ cornea
What is this?
Corneal laceration, iris prolapse and lens extrusion
Lens extruded – need to remove eye
How can we diagnose sudden vision loss?
–Electroretinogram (ERG) to assess retinal function
–MRI scan to see if they have gone blind de to something in the brain
Name differentials for sudden vision loss?
- Acute glaucoma
- Acute uveitis
- Intraocular haemorrhage
- Retinal detachment
- Optic neuritis –swollen ON can be difficult to se. Give steroids and reverse blind
- SARD (Sudden Acquired Retinal D egeneration)
- Toxicity (ivermectin, enrofloxacin in cats)
- Intracranial lesion e.g. tumour
- If you cant see anything then the chances are its one of the last 4 so then you can ERG or scan. Cant give prognosis and treatment plan unless you know
