THE WEBINAR VET. K9 Ulcers: Drops, Cut or Refer. Guy Clare MA BVSc CertVOphthal E: 8/11/2016

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1 THE WEBINAR VET K9 Ulcers: Drops, Cut or Refer Guy Clare MA BVSc CertVOphthal E: 8/11/2016 Corneal anatomy; Corneal Ulcer Diagnosis; Corneal Ulcer Aetiology; The Boston Terrier; Indolent Ulcers and Stromal Ulcers

2 Corneal Anatomy Corneal Anatomy Schematic 2

3 Ulcer Diagnosis 1. FLUORESCEIN EXAMINATION: if +ve ulceration Fluorescein examination is, in my opinion, mandatory in every painful eye AND before prescribing topical steroids. It is invaluable for detecting defects in the corneal surface (ulceration) Place dye (either from the wettened dye impregnated strip or from the single use fluorescein solution pipettes) on the conjunctiva, close the lids and then flush the cornea with copious amounts of water Dim the lights and view the cornea with the aid of the blue filter on the direct ophthalmoscope or Woods Lamp to highlight fluorescence in regions where there is a corneal surface defect. a. If there is an indolent ulcer there will be evidence of non-adherent epithelium around the edges of the ulcer due to fluorescein penetrating beneath the flap of epithelium. The presence of under-running makes the diagnosis of an indolent ulcer (see below for suggested management) b. If the walls of an ulcer fluoresce and the bottom of the well doesn t then this should be noted as a very deep ulcer a descematocele as Descemet s membrane does not stain with fluorescein. The eye is one cell thickness away from rupturing Ulcer Aetiology BANDIT Aetiology of corneal ulceration: - Breed Aberrant hair abrasion Entropion Distichiasis Ectopic Cilia Trichiasis Eyelid Agenisis Congenital dermoid Nerve palsy: - 3

4 V: sensory to the cornea. PALSY neurotropic keratitis corneal ulceration VII: motor to orbicularis oculi lid closure. PALSY exposure keratitis and highly likely ulcerative keratitis Dry eye Irritants (acid / alkali), Immune mediated, Iatrogenic, Infective (not in the dog) & Idiopathic Trauma either linear or puncture / foreign body especially organic material held onto the cornea by surface tension and grass seeds The Boston Terrier A Classic Breed from an Ophthalmic Perspective because: - 1. Corneal endothelial dystrophy i.e. an endothelial reason for corneal oedema which is progressive and can bullous keratopathy and superficial corneal ulceration Other breeds include Chihuahua; Dachsunds; German Short-haired Pointer; German Wire-haired Pointer 2. 2 Cataract Models: - EARLY genetic test available and manifests as blindness due to mature cataract by 3yo LATE no genetic test available, manifests before 8yo and rarely progresses to blindness Other breeds include: SBT; French Bulldog; Australian Shepherd 4

5 INDOLENT ULCER: Affects any breed, but the Boxer and Pembroke Corgi are over-presented Ulcer occurs as a cleavage plane between the basal columnar layer of the corneal epithelium and it s basement membrane Areas of non-adherent epithelium cause under-running Pain is very common however corneal oedema is generally NOT a feature of these types of ulcers as the basement membrane of the epithelium is intact SCCED ulcer: Superficial Chronic Corneal Epithelial Defect, although I think that SPONTANEOUS Chronic Corneal Epithelial Defect is a better name This type of ulcer has no known infective aetiology, rather is a problem of healing and therefore treatment needs to be aimed at stimulating healing Indolent Ulcer Management Decide whether you are going to treat with the animal conscious or following an anaesthetic. The key steps for repair are: - adequate debridement of the non-adherent epithelium and then subtle damage to the superficial stroma so that the necessary growth factors are released to allow formation of the junctional complexes that bind the basal, columnar layer of epithelium to it s basement membrane (hemi-desmosomes) If conscious (DROPS) approach elected for: - a. Apply topical local, and debride with a cotton bud b. You can often perform a grid with a compliant patient (but always muzzle for confidence) and use a 25G needle c. I sometimes offer a contact lens d. Medicate with: - i. Chloramphenicol topically q 6h ii. Mydriatic (Mydriacyl or Atropine I now prefer Mydriacyl in this instance) iii. Sodium hyaluronate 0.15% or >0.15% topically q 6h (to act as a liquid contact lens iv. NSAID PO (although this is controversial) If GA (CUT) elected for: - a. One touch approach to manipulating the eye rat tooth Adson forceps at the medial aspect grasping conjunctiva beneath the third eyelid b. Superficial keratectomy using the back of a number 11 scalpel blade c. 25G needle to create grid keratotomy brick-work as opposed to noughts and crosses d. Third eyelid flap (TEF) for 14 17d, there should be NO blepharospasm whilst the TEF is in place. If there is then the TEF should be removed and the cornea assessed e. Medicate with topical chloramphenicol and systemic NSAID DO NOT OBSCURE THE VIEW OF THE CORNEA WITH A THIRD EYELID FLAP OR TEMPORARY TARSORRHAPHY IF YOU ARE NOT 100% HAPPY WITH YOUR DIAGNOSIS 5

6 STROMAL ULCERS: (beware any ulcer where there is corneal oedema) With stromal involvement ASSUME destructive collagenases have been switched on and therapy should be aimed at reversing these changes. This can be achieved by: - INTENSIVE TOPICAL (DROPS) REGIME Use a powerful topical antibiotic with a high chance of Pseudomonas spp sensitivity i.e. tobramycin, ofloxacin, ciprofloxacin, gentamicin, framycetin q 2h Take blood to make autologous plasma (or serum or blood) drops q 2h o I collect 10-20mls of blood into Lith Hep blood tubes o Spin the Lith Hep tubes down in the centrifuge and collect the plasma o Place the plasma into EDTA blood tubes filled to the level that you would normally add blood to o Dispense with several 1ml syringes (to suck-up the plasma / EDTA drops and administer onto the affected eye(s)) o LABEL: Apply 1 drop every 2h onto the affected eye(s) until further notice o Keep refrigerated, will last for up to 10d Use a topical mydriatic MYDRIACYL (tropicamide 0.5 or 1%) q 8h or atropine q 24h until pupil dilation is achieved (beware the possible side effect of reducing tearing with topical atropine and hyper-salivation due to its bitter taste) Ca2+ Chelator: - o Systemic doxycycline 10mg/kg q 24h PO for it s action as an anti-protease as opposed to it s anti-bacterial spectrum Systemic NSAID (controversial, but I like it to try and lessen the risk of secondary uveitis) Systemic antibiotics, in my experience, are less important Good signs associated with healing are: reduced corneal oedema, reduced pain and epithelialisation of the lesion (therefore it becomes fluorescein negative) Stromal ulcer prognosis: With a conservative approach brief the owners about the intensive topical regime and the requirement for this to be continued for at least the first 72h. I give owners a < 50/50 chance that this will result in the eye eventually healing. With surgery (debridement of the ulcer followed by a conjunctival pedicle graft) then I often give owners a 95% chance of healing. The topical regime is less arduous (q6h) following conjunctival pedicle graft surgery and costs in Australia are in the region of $2400 to $2600. DO NOT OBSCURE THE VIEW OF THE CORNEA WITH A THIRD EYELID FLAP OR TEMPORARY TARSORRHAPHY IF YOU HAVE CORNEAL OEDEMA, AIM THERAPY AT SWTICHING OFF PROTEASE ACTIVITY OR REFER FOR CONJUNCTIVAL PEDICLE GRAFT SURGERY 6