Ophthalmic emergencies Flashcards
(33 cards)
What is an ocular emergency?
- a condition that threatens vision and/or the globe itself
Examples of ophthalmic emergencies
- traumatic globe prolapse (aka traumatic proptosis)
- retrobulbar abscess
- acute glaucoma
- anterior lens luxation
- corneal emergencies
- sudden onset blindness
Globe prolapse vs exophthalmos
Globe prolapse
- globe is acutely displaced forwards beyond the plan of the eyelids
Exophthalmos
- a degree of forward displacement of the globe with the eyelids remaining in a normal anatomical position
Pathophysiology of globe prolapse
- immediate oedema of conjunctiva and orbital soft tissue -> further exacerbated by the eyelid spasm (obstructs venous drainage leading to more swelling)
- traction on optic nerve likely to result in permanent blindness
- desiccation of ocular surface -> potential for corneal ulceration
- rupture of extra ocular muscles
How skull shape influences orbit shape - brachycephalic breeds
- shallow orbits impart very little protection for eye
- very little force required to cause prolapse
- easy to replace, better prognosis
Feline globe prolapse
Cats have deeper orbits and therefore better protection
- large amounts of force required to prolapse globe
- head trauma in an RTA
Globe prolapse - replace or enucleate?
In theory better prognosis if:
- brachycephalic
- positive PLR
- eye that attempts to move
Worse prognosis if:
- cat or dolichocephalic breed
- hyphaema
- corneal/scleral rupture
If in doubt, attempt replacement - can enucleate later if needed
Enucleate immediately if attachments almost all severed or if optic nerve is severed
Globe prolapse - tx
Why:
- needs treating immediately: by you rather than by referral
- rapid tx will improve prognosis for vision and globe
- distressing to animal & O
- painful
Prep:
- keep globe moist - lubricating ointment (if pt allows)
- prevent self-trauma with buster collar
- provide analgesia/sedation
- GA for globe replacement once stable
— ± clip hair
— prep area with aqueous povidine-iodine solution or sterile saline
Tx:
- lateral canthotomy
— make eyelid opening larger by cutting skin at lateral canthus
— reduces pressure on globe and makes replacement much easier
- pull eyelids outwards, forwards, up and over globe
— stay sutures, spay hooks, Allis tissue forceps
- simultaneous gentle pressure on globe (wet swab) to replace back into orbit
- repair lateral canthotomy
— double layer closure with figure of 8 at eyelid margin
— 4/0 - 6/0 polyglactin (Vicryl)
- temporary tarsorrhaphy
— (suture eyelids together)
— to prevent re-prolapse and tamponade haematoma and oedema within orbit
— 5/0 vicryl
– 3-4 simple interrupted or mattress sutures ± stents (to stop the sutures pulling through)
— needle must emerge from the eyelid margin or just in front, must not go full thickness through eyelid (risk of suture rubbing on the eye)
Globe prolapse - aftercare
- systemic antibiotics (amoxyclav good) and anti-inflammatories
- broad spec topical antibiotic (if have left a small gap at the medial side for drops to be put into)
- buster collar
- re-evaluation after 10-15d to remove sutures and decide if enucleation is required
Globe prolapse - prognosis
Must manage O expectations
Prognosis for vision
- guarded
- most eyes are blind (80% dogs, ?100% cats)
Prognosis for retaining globe
- reasonable (most O prefer blind eye to no eye)
- other complications: lagophthalmos, neutrophil keratitis (animal can’t feel surface of the eye so can damage it / get ulcers), dry eye, permanent strabismus
Retrobulbar abscess - what is it?
- abscess or cellulitis behind globe
Retrobulbar abscess - CS
- acute onset
- unilateral
- exophthalmos (proptosis)
- pain, esp on opening the mouth
— ramus of mandible puts pressure on eye hence pain when opening mouth - 3rd eyelid protrusion and swelling
- ocular discharge
- pyrexia, lethargy
- direction the eye is pushed is usually where the lesion is
- retropulsion of both eyes: one with abscess will not retropulse very well
Retrobulbar abscess - diagnosis
- CE & CS
- US: look for fluid-filled cavity
- look in mouth
— (remember close proximity of upper dental arcade to soft tissue floor or orbit)
— tends to be swelling behind the upper rear molar
Retrobulbar abscess - tx
- drain abscess under GA
- access to soft tissue floor of orbit via mouth
- scalpel incision, insert artery forceps blindly into retrobulbar space
- remember most eyes are 2cm from cornea to sclera
- release pus (if get pus, swab for C&ST)
- pressure around and traction on optic nerve can cause temporary blindness, and if not tx urgently, permanent blindness
- medical management
– systemic NSAIDs
– systemic antibiotics, start with amoxyclav whilst waiting for C&ST, 2w course
– may need IV fluids and injectable meds if not eating
– topical lubricants until normal blinking returns
Acute glaucoma - CS
- ocular pain (classic triad):
— blepharospasm
— increased lacrimation
— photophobia - head shy, yelping, dull/quiet
- vision loss
- change in appearance
- corneal oedema (when IOP >40mmHg)
- episcleral vesels congestion
- fixed, dilated pupil (no PLR)
— eye can’t see, pressure on optic nerve means animal can’t see
— high pressure will paralyse the muscles in the iris so no PLR
What 2 groups of dogs are predisposed to acute glaucoma? & how to differentiate
Pure breed dogs
- with hereditary primary glaucoma
- spaniels, retrievers, bassets, huskies
Terrier breeds
- with acute lens luxation and secondary glaucoma
How to differentiate?
- is it a predisposed breed?
- can you see an underlying cause? (uveitis, lens luxation)
Acute glaucoma - diagnosis
Tonometry: measure IOP
- normal range in dogs & cats: 10-25mmHg
- acute glaucoma: often >40mmHg, may see IOPs of 60-80mmHg
Acute glaucoma - tx
Reduce IOP - choice of meds depends on underlying
- prostaglandin analogue (Latanoprost) if suspect primary
- carbonic anhydrase inhibitors (brinzolamide, dorzolamide) always ok
- IV mannitol if not responding to drops (not often stocked in practice)
Analgesia
Seek referral advice / offer referral ASAP
Primary glaucoma is a bilateral condition
- consider referral assessment of other eye
Causes of lens luxation
Primary
- hereditary weakness in lens zones, terrier breeds predisposed
- secondary: may follow glaucoma, uveitis, cataract
Types of lens luxation & which is an emergency
Lens may move anteriorly or posteriorly - anterior lens luxation is an ophthalmic emergency
Anterior lens luxation - CS
- acutely painful eye
- glaucoma (episcleral injection, raised IOP, diffuse oedema, vision loss)
– lens moving out of place blocks the draining angle therefore often get acute glaucoma - focal cornea oedema
- lens outline may be visible in anterior chamber
How to decide if lens luxation or primary glaucoma?
Is it a predisposed breed?
- if a terrier assume anterior lens luxation until proven otherwise
Does the dog have a hx of either problem?
- if 1 eyed dog, check why the other was removed
If very cloudy
- take a photo with flash
- consider US
Look at the other eye for clues - bilateral condition
Anterior lens luxation - tx
Offer referral: emergency surgical removal of lens or ‘couching’ to push lens backwards
Analgesia
- e.g. oral NSAID and opioid
Anterior lens luxation - ongoing management
Bilateral condition
- contralateral eye likely to be affected but at an earlier stage i.e. subluxation
- consider referral assessment / prophylactic tx
- if eye is enucleated, send for histopathology
