Painful eyes and ocular emergencies (ECA week 12)

Question 1

What should be used if eyelids are too swollen to examine an eye?

Answer 1

Use ultrasound to check for structural damage to the globe
If normal then can tell owner good prognosis even without examining the eye

Question 2

Auriculopalpebral nerve block - How to do it? What does it block? When to use it?

Answer 2

Blocks motor supply to the upper eyelid

Use for placing SPL system, or for examining painful eye if needed - don’t want to force the eye open too much as may have a structurally weak eye e.g. if deep ulcer

Feel nerve as run finger over zygomatic arch (feels like spaghetti), inject 2-5ml LA

Question 3

What should always be done to check for corneal damage?

Answer 3

Stain the eye with fluorescein. Can also give idea of depth of ulcer.

Question 4

True or False: Fluorescein can be reused for multiple cases.

Answer 4

False. Single use pipettes.

Question 5

How to check the eye for foreign bodies?

Answer 5

LA to surface of eye
Run gloved finger under conjunctival fornix looking and feeling for FB
Look under third eyelid by prolapsing it and then holding with atraumatic forceps

Question 6

What is the Seidel test used for?

Answer 6

To check for penetration of the globe

Question 7

How is the Seidel test performed?

Answer 7

Block upper eyelid, apply fluorescein, observe for aqueous humour leaking

Question 8

When to use cytology and culture for eyes?

Answer 8

Particularly for contaminated/complicated ulcers or if suspecting fungal keratitis etc

Question 9

How to take a sample for culture of the eye?

Answer 9

Sedation and AP block
Ideally no topical LA - though studies shown minimal effect on results
Normal charcoal swab
Roll onto microscope slide and stain with diff-quick (or send away)

Question 10

What should be used for cytology sampling?

Answer 10

Cytology brush
Fine to use topical LA

Question 11

What is a method to protect a painful eye from self-trauma?

Answer 11

Use commercial masks with hard cup or make a donut dressing

Question 12

Describe how to make a donut dressing to protect a painful eye from self trauma or during transport etc.

Answer 12

At the end of a cotton wool roll there is a thin piece of rolled up cotton - roll this into an ‘O’, cover with dressing material and attach to head with tensoplast

Question 13

How to decide whether to place a subpalpebral lavage system on the upper or lower eyelid?

Answer 13

May be determined by area of pathology, but if not then consider advantages and disadvantages to both

Upper eyelid:
- Some people think more difficult due to deeper fornix (but some people find easier with fingers pointing up to place)
- Higher risk complications especially if becomes displaced
- Better drug distribution

Lower eyelid:
- Some people find easier to place
- Reduced rate of complications (poss due to protection from third eyelid if becomes displaced)
- Decreased absorption of medication

Question 14

What are the steps for placing a subpalpebral lavage system?

Answer 14

1. Sedate the horse well
2. Block the eyelids:
   - If doing upper eyelid: auriculopalpebral (motor) and frontal (sensory to most of upper eyelid) nerve blocks
   - If doing lower eyelid: local injection SC where lavage system will come out (medial section of eyelid)
3. Anaesthesia of corneal surface - proxymetacaine/tetracaine (can’t use other LA on surface of eye)
4. Eyelid skin preparation - clip and scrub area where lavage system will exit and where sutures will be placed
5. Identify conjunctival fornix (where the palpebral conjunctiva turns into bulbar conjunctiva - push finger over/under eye until hit the blind sac)
   - For lower eyelid the fornix is less deep, aim between lower and third eyelid (medial but not too far medial as don’t want to damage puncta of nasolacrimal system)
   - For upper eyelid aim for central eyelid with same distance from medial and lateral canthus.
6. Protect tip of needle with finger (finger against eye) and insert through eyelid - can use second hand to separate needle from finger once in fornix and advance
7. Pull the catheter through eyelid until footplate is in place
8. Connect injection port
9. Secure the system: plait forelock and one in mane - catheter threaded through these. Secure catheter to head (with tension so footplate doesn’t become displaced) with tape butterfly wings with suture either side of wings to head or can thread tubing directly under skin a couple of times with same needle (friction of sc tissue keeps in place). Secure injection port to tongue depressor and tape to plait of mane at base of neck. Tips - if comes with injection port catheter, pull stylet back slightly so don’t puncture tubing when inserting. If comes with blunt ended needle to insert, cut tip of needle cap off and thread cap over tubing, then thread needle to end of tubing, then bring needle cap back onto hub of needle to give structural support.
10. 0.2-0.3ml medication, gently followed by air until horse starts to blink, allow 10-15 mins between medications. If just using one medication, can fill whole tubing with medication instead, as really do hate air. If frequent medications necessary in severe cases, consider infusion pump.

Can stay in place for weeks and weeks, but need maintenance: every day check for displacement of system from conjunctival fornix, check injection port, check sutures, check medication visible on ocular surface following administration

Question 15

What should be blocked if performing a subpalpebral lavage on the upper eyelid?

Answer 15

Auriculopalpebral (motor to upper eyelid) and frontal nerve blocks (sensory to most of upper eyelid)

Question 16

What technique is used to locate the supraorbital foramen during a frontal nerve block?

Answer 16

Pass finger over dorsal orbit to feel for a depression

(Right photo)

Question 17

What is the recommended examination following blunt trauma? History?

Answer 17

Complete exam, including neuro exam with cranial nerves (might be brain traima)
Ultrasound if eyelid inflammation does not allow ocular exam

Consider why it happened - colic? Fall?

Question 18

What imaging techniques are useful for checking fractures after blunt trauma to eye?

Answer 18

CT very useful, but if not available radiography can be helpful and US looking for incongruity/depressed bone

Question 19

What are the most common clinical finding following blunt trauma?

Answer 19

Cataracts (66% of cases)
Corneal oedema (77% of cases)
Reduced IOP (42% of cases)
Aqueous flare (35% of cases)
Luxation, subluxation or loss of lens (33% of cases)
Fibrin in anterior chamber (33% of cases)
Hyphaema (29% of cases)
Rupture of granula iridica (26% of cases)
Retinal detachment (13% of cases)

Question 20

How quickly can a cataract form following blunt trauma?

Answer 20

Within a matter of days

Question 21

What is the treatment for corneal oedema?

Answer 21

No specific treatment
Can apply 5% topical saline to try to draw some of the oedema away

Question 22

Does a luxated lens always need to be removed?

Answer 22

Not always - some cause no problem (usually if posteriorly subluxated)
Remove whole lens if causing problem (some have cataract affecting vision, some can drive glaucoma)

Question 23

Treatment of hyphaema after trauma?

Answer 23

Some textbooks recommend injection of TPA into anterior chamber

Fernando is more conservative these days - as long as treat primary problem then blood and fibrin will resolve in a matter of days for vast majority of cases, so generally can avoid the risks of injecting

Question 24

What should be used to prep the eyelid area before repair of an eyelid laceration?

Answer 24

Saline or dilute iodine (1:50)
Not chlorhexidine near eyes!

Question 25

What suture material size is recommended for eyelid repair?

Answer 25

4/0 - 6/0

Question 26

Which eyelid laceration can be more problematic?

Answer 26

Upper - responsible for 60-70% of the tear film coverage of the ocular surface But if medial lower eyelid, may have damaged palpebral puncta - warn owner may have epiphora for rest of life

Question 27

Key points for eyelid repair?

Answer 27

Debride as little as possible - excellent blood supply, so even dubious tissue will probably survive Meticulous repair If not happy with the finish, remove sutures and start again Referral if needed, especially if not compliant and GA needed (better to do this than have lifetime of ocular issues) Can do figure of 8 stitch first to oppose edge and then continue along Or can just do simple stitch to start with (like Lavach photo) and then continue on from there simple interrupted - may need to remove previous stitches as go along as things move Make sure no stitches against cornea If not proud of job, then not good enough!

Question 28

What are clinical signs of ulcerative keratitis?

Answer 28

Pain, blepharospasm, epiphora, photophobia

Question 29

What is the rate of healing of superficial corneal ulcers?

Answer 29

Officially 0.6mm/day, but probably quicker than this if no complicating factors

Question 30

How does the appearance of a deep ulcer differ to a superficial corneal ulcer?

Answer 30

Superficial - cling film appearance Deep - crater

Question 31

How does the treatment for a deep corneal ulcer differ from a superficial ulcer?

Answer 31

The same, just treat for longer Warn owner permanent scarring likely following deep ulcer

Question 32

What is keratomalacia? Treatment?

Answer 32

Melting ulcer caused by activation of proteolytic enzymes by corneal epithelial cells, leucocytes and microbes -> destruction of stroma Requires early aggressive therapy - cornea can melt away and rupture within a matter of hours Topical serum (collect in plain tube, allow clot to form, then centrifuge) or topical EDTA (saline in EDTA tube, then move to another EDTA tube to double the dose) - both very effective Topical acetylcysteine can also be used Topical tetracycline or doxycycline - have immunomodulatory effects and will inhibit enzyme action Systemic flunixin - both as analgesia and anti-inflammatory action

Question 33

What is a descemetocele? Treatment?

Answer 33

Ulcer with only Descemet’s membrane and endothelium remaining Emergency - eye is very weak Fluorescein negative, not very painful Aggressive therapy needed - same as for deep melting ulcers, plus probably need atropine: - Topical serum (collect in plain tube, allow clot to form, then centrifuge) or topical EDTA (saline in EDTA tube, then move to another EDTA tube to double the dose) - both very effective - Topical acetylcysteine can also be used Topical tetracycline or doxycycline - have immunomodulatory effects and will inhibit enzyme action - Systemic flunixin - both as analgesia and anti-inflammatory action Surgical therapy often advised - conjunctival flaps, amnion grafts If referral for surgery not an option, consider tarsorraphy (surgically closing the eyelids) or contact lens (both less ideal)

Question 34

What is the prognosis for surgical repair of full corneal thickness laceration with iris prolapse?

Answer 34

65-80% success suggested, unless complicating factors making poorer prognosis

Question 35

Treatment of a full corneal thickness laceration with iris prolapse?

Answer 35

Enucleation tempting and is option But also can attempt to manage medically - treat same as a deep ulcer. With time might settle - prolapsed iris might incorporate into cornea and close the penetrating defect. Iris shape will be affected and likely synechia but some cases do really well. Key is to control infection within the eye as much as possible - if infection sets in then hopeless prognosis. Surgical repair is ideal - 65-80% success rate

Question 36

What makes a full thickness laceration with iris prolapse have a poorer prognosis?

Answer 36

Secondary to long standing ulcer as margins more irregular and poorer quality so more difficult to surgically repair (prognosis better if from acute sharp injury) >15mm Keratomalacia Hyphaema Extension beyond limbus - more structural damage to eye Complications: infection, uveitis etc

Question 37

What is the leading cause of blindness in horses?

Answer 37

Uveitis

Question 38

What are the types of uveitis?

Answer 38

Anterior, posterior, pan-uveitis (most are pan) Primary or secondary (e.g. to ulcer, Rhodococcus in foals) Single event, chronic (if no response to treatment), or recurrent (resolves but recurs)

Question 39

What are the signs and features of acute anterior uveitis?

Answer 39

Ocular pain, blepharospasm, lacrimation Might have corneal changes: oedema, vascularisation, cellular infiltrate, keratic precipitates, neovascularisation Aqueous flare (rupture of ocular blood barrier so leakage into anterior chamber → turbid aqueous humour - easier to see with slit lamp), hypopyon, hyphaema Miosis, iris colour changes Low intraocular pressure

Question 40

What are the signs and features of acute posterior uveitis?

Answer 40

Less common or less commonly noticed? Obvious pain less consistent Vitritis with liquefaction of the vitreous Vitreal floaters, vitreal flare Retinal changes

Question 41

What is the treatment for uveitis?

Answer 41

Atropine - relieves pain from spasm of ciliary body, avoids complications like synechiae, stabilises blood-ocular barrier, q4hrs until achieve dilation of pupil, don’t worry too much about risk of slowed motility (pain will also affect this) but have owner to monitor faecal output Topical corticosteroids (systemic sometimes) - as often as possible e.g. 3-4 times per day at least, pred or dex both fine, pred in theory better penetration. Treat for 6 weeks after resolution of signs with some form of continued anti-inflammatories - longterm topical steroids not ideal, but could reduce frequency to once per day for 6 weeks, or instead systemic NSAIDs for 6 weeks - reduces likelihood of chronic or recurrent uveitis If ulcer can use topical NSAID instead of steroids - effect not as potent. Systemic flunixin - more potent than bute for ocular pain

Question 42

What does aqueous flare indicate?

Answer 42

Rupture of ocular blood barrier with uveitis -> turbid aqueous humour

Question 43

What is the recommended duration for treating uveitis with anti-inflammatories (once per day topical steroids or systemic NSAIDs) after resolution of signs?

Answer 43

6 weeks