Sunday, July 31, 2016

2900. Continuing education: Recent Advances in Ocular Therapies by Robin G Stanley

July 31, 2016

I attended Continuing education: Recent Advances in Ocular Therapies by Dr Robin G Stanley, Animal eye Care, Melbourne today.  His website is animaleyecare.com.au. An excellent presentation.

1. Acute Glaucoma


PROSTAGLANDIN AGONSITS - increase outflow, decrease production of aqueous
a. Xalatan - lantanoprost
b. Travatan - travaprost
Not for luxated lens in anterior chamber (2nd glaucoma)
Not effective in cats

Lantaoprost is very very effective for acute glaucoma. IOP of more than 40 mm Hg back to normal within 90 min (new aqueous production every 90 min)  after a single drop in most cases. Used once daily. Ineffective after 6 weeks in most dogs, possibly related to receptor saturation. Ineffective in cats as cats have no receptors.
Expensive. A$25/2.5 ml. Use generics. Check IOP

2. Secondary Glaucoma

TOPICAL CAIS (carbonic anhydrase inhibitors) decrease production of aqueous, no effect on outflow. More effective than oral CAIs and no systemic toxicity. He seldom use oral CAIs as topical CAI are very effective, not good for primary glaucoma, work better for 2nd glaucoma and seem to be more effective with time.


a. Azarga - Brinzolamide/Timolo (recommended, newer drug with anti-inflam properties)
b. Cosopt - Dorzolamide and Timolo (mainly used to treat ocular hypertension - slightly increased IOP, reduces IOP by 15-20 mm Hg. More effective in reducing IOP when drug is used longer.
Used for the other eye (predisposed eye) to reduce the risk of glaucoma when one eye is affected as this glaucoma develops few months later.


c. Trusopt - Dorzolamide
d. Azopt - Brinzolamide

Technique in taking IOP important as dog struggles, increase IOP.
Uveitis - IOP should be low.  IOP can be a guide to effect of anti-inflam therapy.

SYSTEMIC CAI eg. Daranide or Diamox.

OPTIC NERVE DAMAGE IN GLAUCOMA. No drug.


GLAUCOMA PROPHYLAXIS
1. Do not use prostanoids due to receptor saturation ie. lose their effectiveness over time
2. Other vets use Timolo and Pilocarpine
3. Cosopt  --  mainly used to treat ocular hypertension - slightly increased IOP, reduces IOP by 15-20 mm Hg. More effective in reducing IOP when drug is used longer.
Used for the other eye (predisposed eye) to reduce the risk of glaucoma when one eye is affected as this glaucoma develops few months later.

FELINE HYPERTENSION
1. Amlodopine is very useful. Cats 5 mg tablet. 1/4 to 1/8 sid. More effective than fortekor, enalapril. Retinal haemorrhage (scope)
most old cats have high BP, not treated -- retinal haemorrhage. use Amlodopine. Bubbles intapetum. Measure BP
cat fundus uniform unlike dones.

INFECTED CORNEAL ULCER

Image - eye hypopyon,ulcer melting. swab for culture, gram staiing, sensitivity

Can melt - keratomalacia
Usually Pseudomans or a B Haemolytic Strept. Do culture and sensitivity
Causes excess release of collagenase that dissolves/melts the cornea.
Use fortified gentamicin OR
fluoroquinolones with Conoptal (fusidic acid)
Need to use 6-8x/day

Rather than fortifying
use drops frequently
use every 5 min for the first hour and then hourly for the first day.



THERAPY FOR MELTING CORNEAL ULCER EYE SHOWN IN SLIDE
fortified gentamicin 6 x daily
doxycycline 5 mg/kg bid
atropine Minims a drop to keep pupil dilated
Oral NSAIDs
Nowadays, less use of conjunctival flap surgery (cut off cornea, put flap in) and more use of drugs for melting corneas.
Chloramphenicol eye ointment used by some vets
Gentamicin is toxic in eye drops?

INDOLENT ULCERS IN CATS
usually viral cause
some related to poor quality tears

VIRAL KERATITIS IN CATS
feline herpes virus
stress seem to be important factor e.g. been to cattery, behavioural causes
FELOWAY - feline appeasing pheromone.

Viral keratitis
- dendritic ulcers (slide shown of branching ulcers due to viral spread)
-geographic ulcer (slide showing large ulcer on surface of cornea, like country in a sea as seen in a map)

TOPICAL ANTI-VIRALS
CIDOFOVIR most effective. 1 drop bid. 98% heal within 10 days
Idoxuridine
Acicylovir (Zovirax)
Betadine (Iodine) eye drops

ORAL ANTIVIRALS
Famciclovir 40 mg/kg tid
Compounded by pharmacists with fish paste but some cats dislike it.
Use artificial tears
Use lysine 500 mg orally bid. long term once daily. minimize rate of recurrence. increase to bid if stressed.

interferes with viral replication


ORAL DOXYCYCLINE FOR VIRAL KERATITIS, CORNEAL ULCERS AND CONJUNCTIVITIS

Many cats with viral keratitis have chlamydia infections
5 mg/kg bid
No need topical meds according to Dr Stanley as doxy is sufficient.

Feline conjunctivitis
As in viral keratitis 5mg/kg bid rather than 2.5 mg sid. Sufficient conc in cornea and conjunctiva, so no topical therapy.

Chlamydophyla is a systemic disease and need systemic therapy.


INCREASED RISK OF INFECTION

eg. dry eye, stromal ulcer etc
topical Abs are also needed
- triple AB combination
conoptal
NOT gentamicin or fluoroquinolones unless the ulcer is infected.

FELINE CONJUNCTIVITIS
Zithromax (azithromycin)
useful in a cattery situation  large no. of cats
but doxycycline more effective, has anti-inflam effect which may promote corneal healing. May have some anti-corneal melting effect.
cytology  culture

ANTI-INFLAMMATORIES
1. Topical NSAIDs - voltaren (diclofenac) or Acular (ketorolac) eyedrops
2. Mainly used to reduce  corneal scarring after vascularization in corneal ulcers AND for management of lens-induced uveitis.
3. cornea at risk of ulcerating   eg. keratitis
4. not use for ulcerated cornea.
5. can potentiate corneal ulceration
6. in keratitis treatment, not as effective as topical cortisones e.g. Pred Forte and Maxidex
    esp. diabetic cataract.
7. use topical NSAIDS in viral keratitis in cats. Topical cortisones can reactivate a patent herpes keratitis
8. Oral NSAIDS 80% as effective as systemic steroid. Start on oral doxycycline.

Systemic NSAIDS
Dogs:  Carprofen 2.2 mg/kg bid 3 days then sid
Cats:  Metacam suspension seems to work well in controlling uveitis and ulcers in cats


SEVERE UVEITIS
He will initially use cortisone by all routes e.g. topical, systemic and subconjunctivally
(Image - eye with miosis, hypopyon, inflame uvea)
Sedate and given subconj depot cort e.g. dexa forte. Makes a big difference.  Atropine to dilate pupil

DRY EYE
1. Clear eye of all pus etc before applying optimimmune


ARTIFICIAL TEARS
1. in human studies, better corneal health
2. Refresh Tears Plus
3. Hyaluornate-based drops e.g. Luxyal or Hyloforte (comes as a pump, last longer, more viscous preparation)
Replace quantitiy of tears and increase quality
Systane Hydration Tears for cat flu
4. last only 1-2 hrs on the cornea.

TACROLIMUS
Next wonder drug for dry eye?  Better than Optimmune.
Effective in dry eye cases unresponsive to cyclosporine.
3x/day if cyclosporine not working.
Like cyclosporine, Tacrolimus is used for stopping graft rejection. Trade name is Profraf, FK506
3x/day if Optimmune is not working

Unresponsive Dry eyes
Use Tacrolimus and cyclosporine together
Tacro 3x/day, 15 min later, cyclo
4-6 weeks to get results

Tacro used in inflamed corneal ulcers. makes a difference.





EYE SURGICAL INSTRUMENTS
1. (Thin narrow forceps)
2. Needle driver.
3. Ziegler cilia forceps
4. Thorton open wire lid speculum with lifting wings - better than usual eyelid retractor which is heavy.
5. Stevens tenotomy scissors

PREMEDICATION
1. Premed with injectable NSAID esp. corneal  intraocular surgery. send home with oral NSAIDs
2. Prem with broad spectrum antibiotics.. Generally no follow up with oral antibiotics.

SURGICAL DISINFECTION
3. Betadine iodine solution, not the one type you use for scrubbing
4. dilute 1 part betadine to 9 to 25 parts saline. Not to use water as the ionic nature of the diluent makes the iodine more active.
5. Prep in usual manner.

WATERY EYES
Entropion, puncta atresia (slide of Golden Retriever). extra eye lashes. Schmir tear test 15 is normal.

TEAR DUCT FLUSH
Watery eye - lack of nasolacrimal fluorescein passage
Fluorescein dye appears at nostrils (slide shown).
use lacrimal cannulas or hypodermic needles bent over and the tip broken off and filed smooth or use IV catheters (plastic part of IV cathether).
Under GA esp. for cats or sedation. Large dogs c b flushed with local anaesthetic
Flush thru to the nose so, point the nose down
If unable to flush, try passing suture  down the N/L duct and in large breed dogs, try a retrograde flush from the nose back into the eye (like in horse).
(Image of illustration of needle flushing superior puncta and fingers pressing eye area shown).

If still blocked, flush eye again a couple of weeks later.
lazy tear ducts - tell client that some breeds, the tear ducts are not blocked. but the eye is watery with no N/L fluorescein passage through to the nose.  eg maltese, poodles, Persian cats. difficult case to resolve.

TEMPORARY TARSORRHAPHY
Can be very useful to protect cornea eg. inflamed cornea, superficial ulcer with a dry eye or large eyelid opening.
Split thickness thru the eyelid edge so suture does not rub on cornea. Can be left for months if needed.
TT can be useful in inflamed cornea  (image cornea with lower area vascular vessels)

3RD  EYELID FLAP
Very very useful for corneal disease
If in doubt, flap it
Scarify the bulbar (inside) surface of 3rd eyelid so that it bleeds
monofilament nylon & IV tubing     4/0 cats   2/0 nylon
He is still in favour of 3rd eyelid flap. In Hong Kong, he was expert witness in a case where a HK vet was to be de-registered for using 3rd eyelid flap. Said only 1 case of 3rd eyelid stuck to cornea in 5 years.


(Illustration 3rd eyelid flap -  iv tubing, nylon into upper eyelid, go under upper eylid, across cornea, go above 3rd eyelid and then into tissue of 3rd eyelid, U-turn still  inside tissue 3rd eyelid, back inside tissue eyelid, go  across cornea,  towards upper eyelid and tubing.

Can be a problem in brachcep. the TEF pulls medially, so exposes the lateral cornea. Use TT as well.
IV tubing at lateral canthus?
Concern that flap may stick to cornea. Very rare in his experience. 1 case in 5 years.
Concern that meds may not reach the cornea. yes in theory. give subconju med (gentamicin) and vibravet

INDOLENT CORNEAL ULCER
(Image)
Slow healing
look for underlying casue
Do a STT in all cases of conjunctival and corneal diseases
Check eyelids using magnification
breed predisposition e.g boxers, Samoyed, GR, corgis

MANAGEMENT OF INCOLENT ULCERS
A cotton bud to debride loose epithelium
Grid keratotomy
  Make small incisions into the corena
  DO NOT GRID ODEMATOUS OR INFLAMED CORNEA (Use conj graft).
  90% heal within 10 days
  Image
  25mm needle. Grid 2 mm out into normal cornea
  No need to be well cut grid. Messier, better outcome.
  Grid whole cornea
  Use TEF or TT
Superficial keratectomy
  Refer out troublesome ones

Do not grid non superficial corneal ulcers e.g. stromal ulcers
NEVER GRID A CAT. Get seqestra





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