Equine Ophthalmology Flashcards
Give some clinical signs of ulcerative keratitis
- Bleparospasm
- Pain
- Epiphora (excessive eye-watering)
- Photophobia
What other stain can you use on the eye to check for ulcers?
Rose bengal
Which part of the cornea is damaged with superficial ulcers?
Only the epithelium
How do you treat a superficial ulcer?
- Topical antimicrobials +/- topical atropine
- Healing rate= 0.6mm/day
Which part of the cornea is damaged with deeper ulcers?
- Stroma
- Scarring likely
What is keratomalacia?
Melting ulcer
What causes a melting ulcer?
Activation and/or production of proteolytic enzymes by:
- Corneal epithelial cells
- Leucocytes
- Microbial organisms (Pseudomonas)
Which bacteria is likely to be in an eye with a melting ulcer?
Pseudomonas
How do you treat keratomalacia (melting ulcers) and descemetoceles?
- Topical serum
- Topical EDTA
- Topical acetylcysteine
- Topical tetracyclines or doxycycline
- Systemic NSAIDs eg flunixin
What is a descemetacele?
- Melting ulcer that penetrates down to the Descemets membrane
- Will be fluoroscein-negative
How do you treat a stromal abscess?
- Antimicrobials (eg fluoroquinalones)
- May need surgery (debridement or corneal grafting)
What causes viral keratitis?
EHV-2
How would you recognise viral keratitis?
- Multiple superficial, white, punctate or linear opacities
- Varying degree of ocular pain
How do you diagnose viral keratitis?
Difficult: virus isolation +/- PCR
How do you treat viral keratitis?
- Topical aciclovir
- Topical idoxuridine
- Topical Trifluorothymidine
- Topical Aciclovir
- Topical Interferon γ
- Topical corticosteroid?
Are immune-mediated keratopathies usually unilateral or bilateral?
Unilateral
How do you treat an immune-mediated keratopathy?
- Medical: topical corticosteroid, cyclosporine A, doxycycline
- Surgical: keratectomy, cyclosporine A implant
What can happen if uveitis is left untreated?
Blindness
What are the 2 ways anterior uveitis can occur?
- Primary (ie eye trauma)
- Secondary to systemic disease (eg Rhodococcus, Leptospira)
Give the clinical signs of anterior uveitis
- Pain: blepharospasm and epiphora
- Chemosis
- Constricted pupil
- Aqueous flare (milky appearance of anterior chamber)
- Blood, pus or fibrin in anterior chamber)
How do you treat uveitis?
- Topical corticosteroids (if no ulcer)
- Topical atropine (q 4 hours until pupil dilates)
- Topical NSAID (if ulcer)
- Topical antimicrobial? (if ulcer)
- Systemic NSAID (flunixin)
- Surgery: cyclosporine A implant, enucleation?
Give some long-term complications of uveitis
- Atrophy granula iridica
- Synechiae
- Cataracts
- Glaucoma
- Retinal pathology
- Blindness
- Phthisis bulbi
‘Butterfly’ lesions around the optic disc are associated with which condition?
Uveitis
What is the normal intraocular pressure of a horse?
15-30 mmHg
Give some clinical signs of glaucoma
- Hydrophthalmos/buphthalmos
- Corneal oedema
- Corneal striae
- Lens luxation
- Blindness
How do you medically treat glaucoma?
- Carbonic anhydrase inhibitors: topical (dorzolamide) and/or systemic (acetazolamide)
- Topical beta blockers: timolol
- Anti-inflammatories: NSAIDs and/or corticosteroids, topical and/or systemic
How do you surgically treat glaucoma?
- Laser destruction of ciliary body
- Aqueous shunts
- Enucleation
95% of the retinal blood supply is provided by what?
Choroid vessels
Why should you be careful when using atropine?
Can cause gut stasis -> colic
