Equine Corneal Dx Flashcards
Equipment - In Car:
- Ophthalmoscope.
- Pen torch.
- Topical local anaesthetics.
- Fluorescein.
- Needles, syringes, intra-epicaine for
- AP nerve block. *
- Culture swabs & culture medium (or can use blunt end of scalpel).
- Cytobrushes, microscope slides & slide boxes.
- Serum tubes, EDTA tubes.
- Drugs: sedation, systemics NSAIDs, topical abs (ophthocycline ®, chloramphenicol), topical atropine, maxitrol, Pred Forte (fridge) saline.
Equipment - At Practice
- Sub-palpebral lavage kit
- Face masks
- Catheters for flushing nasolacrimal ducts
- US and linear probe
- Drugs - systemic glucocorticoids
Equipment - Referral Centre
Everything listed already plus:
Slit lamp.
Panoptic ophthalmoscope.
Diamond burr.
Tonopen/Tonovet.
Intensive care staff!
Surgical facilities.
Corneal Ulcers - Presentation
- Blepharospasm
- Epiphora
- Reddenedconjunctiva
- Cornealoedema
- Swollen eyelids
Secondary problems: - Anterior Uveitis
- Miosis
- Photophobia
Corneal Ulcers - Pathogenesis and Causes
Bacterial keratitis**
- Strep
- Staph
- Pseudomonas
Fungal Keratitis
- Rare
- Aspergillus
Viral keratitis
Corneal Ulcers - Diagnosis
- Thorough examination of the eye surrounding structures:
- Sedation
- a2 agonist + opioid (Detomidine 10μg/kg + butorphanol 0.02mg/kg iv)
- Local anaesthetics = Tetracaine hydrochloride minim
- Auriculopalpebral nerve block
- Fluorescein dye
- Only a small amount needed.
- Use blue light.
- Rose Bengal dye
- Cytology
- Culture
Auriculopalpebral Nerve Block
- Motor nerve block (facial n. VII) to the orbicularis oculi muscle.
- Prevents closure of eyelids.
- Usually only block necessary
- NB: Does not provide analgesia
Location:
* Nerve palpated along the dorsal edge of the zygomatic arch, just anterior to its highest point.
* 23G 1inch needle
* 1-2mL local anaesthetic (Lidocaine or mepivacaine).
Corneal Ulcer - Tx Aims
6 points
- Address any underlying causes (e.g.: foreign bodies).
- Treat or prevent infection.
- Slow the breakdown/dissolution of corneal collagen. 4. Address any secondary uveitis.
- Provide structural support.
- Analgesia.
Corneal Ulcer Tx
Treat or prevent infection:
* Antimicrobials: Topical (q2-4hrs)
* Antibacterial: Chloramphenicol, Gentamicin,
ciprofloxacin)
* Antifungal: Enilconazole, voriconazole
Slow the breakdown/dissolution of corneal collagen:
* Proteinase inhibitors: Topical
* Serum
* EDTA solution
Treat secondary uveitis
* Atropine topical q24h
Analgesia:
* Anti-inflammatories: Systemic
* NSAIDS usually Flunixin 1.1mg/kg iv initially then
oral
Corneal Ulcers - Subpalpebral Lavage
Easy for vet
Place in lower eyelid as less likely to slip and further damage cornea
Corneal Ulcer - Further Intervention - Grid Keratotomy
- Scratch corneal surface
- Stims healing
Corneal Ulcer - Further Intervention - Diamond Burr:
- Debrides corneal surface
- Stims healing
- Repeated
Corneal Ulcer - Further Intervention - Tarsorrhaphy:
- Stops blinking
- Administer tx via SPL.
- Only once stable.
- Keep for ~1week.
Corneal Ulcer - Further Intervention - Conjunctival Pedicle Flap:
- Suture part of conjunctiva over the defect under GA.
- Leave for 2weeks.
- Protects site.
- Improves blood flow
- Can cause scarring and blind spot.
Corneal Ulcer - Further Intervention - Amnion Graft/ patch
- Piece of amniotic membrane to repair defect.
- Under GA.
- Proteinase inhibiting properties
- Antifibrotic properties
Corneal Ulcers - Non-healing:
Assoc w PPID
Total serum cortisol may be normal but cortisol elevations in tear film.
Immune Mediated Keratitis - Clinical Presentation:
All idiopathic non-ulcerative corneal inflam dx.
Dysregulated immune responses.
Clinical presentation:
* Absence of anterior uveitis in the presence of keratitis.
* Unilateral.
* Corneal oedema, cellular infiltration and vascularisation
* No profound ocular pain.
Immune Mediated Keratitis - Categories:
- Superficial IMMK
- Mid-stromal IMMK
- Endothelial IMMK
Immune Mediated Keratitis - Tx:
Glucocorticoids
* Dexamethasone/Polymixin B/Neomycin (Maxitrol)
* Prednisolone (PredForte) TID/QID
NSAIDs
* Used when GCs contraindicated.
Immunosuppressive agents
* Cyclosporin (Optimmune) BID
Eosinophilic Keratitis - Clinical Presentation:
- bilateral.
- Seasonal: increased in summer and autumn.
- Signs of ocular pain: blepharospasm, epiphora and conjunctival hyperaemia.
Eosinophilic Keratitis - Clinical Presentations
Localised non-progressive:
* Minimal corneal involvement or ocular pain.
* Small, white plaque sometimes seen.
Progressive extensive:
* Marked ocular pain.
* Extensive corneal lesions.
* White plaque formation and secondar infectious
ulceration.
Superficial, multifocal:
* Rare.
* Multiple caseous yellow foci spread over the
corneal surface.
* Moderate to severe corneal oedema.
Eosinophilic Keratitis - Tx:
Glucocorticoids
* Dexamethasone/Polymixin B/Neomycin (Maxitrol)
* Prednisolone (PredForte) TID/QID
* (NB use with care if secondary bacterial ulceration)
Immunosuppressive agents
* Cyclosporin (Optimmune) BID
Antihistamines
* Oral cetirizine (0.4mg/kg BID)
Superficial keratectomy to remove plaques and/or inflammatory debris.
Prolonged recovery: months.
Tear Deficient Keratopathies - Causes:
Keratoconjunctivitis sicca.
* Deficiency of aqueous portion of tear film-
vestibular disease, stylohyoid fx, head trauma.
Evaporative dry eye.
* Enhanced evaporative loss- eyelid abnormalities
and/or reduced blinking (Facial nerve paralysis).
Tear Deficient Keratopathies - Clinical Presentation:
- Blepharospasm
- Mucopurulent discharge
- Dull cornea.
