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What is the first diagnostic process to do when dealing with eye disease?
Clinical examination of whole animal, don't jump straight to the obvious lesion
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Sequence of eye examination:
- Perform in a dark room
- Assess both eyes
- Examine from a distance
- Examine from outside to inside
- Dazzle/menace response and PLR
- Can animal see? Ask owner
- Shirmer tear test and fluorescein
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Entropion
- Breed predispositions: Rotties and Shar pei
- Anatomical defect: need to evert lid to see margin
- Surgical correction: Holz-Celcus
- Puppies: don't ignore, eyelid tacking
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- Eyelid neoplasia
- Mostly sebacious adenoma
- Old dogs
- Full thickness wedge resection - early
- Can remove up to 1/3 length of lid
- Need to avoid 'step' in lid margin
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- "Cherry eye": third eyelid gland prolapse
- Very common in young dogs
- Tx: surgical replacement of glands
- Ddx: scrolling of cartilage of 3rd eyelid - common in giant breeds
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- Keratoconjuctivitis sicca (dry eye)
- Lack of aqueous tear production leads to conjunctivitis & superficial keratitis
- Very sore
- Mucopurulent ocular discharge
- Secondary corneal ulceration
- Dx: STT <10mm per minute
- Very common
- Always perform STT with chronic/recurrent conjuctivitis
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- Keratoconjuctivitis sicca
- This is clinical presentation when aqueous tear production is very low
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- Corneal ulceration: very common in all species
- Dx: fluorescein and close examination
- Tx: dependent on cause, can be surgical or medical
- Always try to determine cause
- Shallow ulcer should heal within a week esp in young dog
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Causes of corneal ulceration
- Dystrophy (eg: boxer ulcer)
- Trauma
- KCS
- Eyelid/eyelash abnormality
- Foreign body
- Exposure (prominent globe eg Peke)
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- Descemetocoele
- Deep ulcer: ophthalmic emergency
- Look at edge of ulcer to estimate depth
- Tx: surgical repair - this is referral surgery, has very high success rate
- Always give owner the option
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- Melting ulcer: liquefactive stromal necrosis
- Complications: Pseudomonas infection - very rapid progression
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- Feline corneal sequestrum
- Very common in cats
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- Equine fungal keratitis
- Usually caused by using topical steroids on ulcerated cornea
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- Infectious bovine keratoconjuctivitis aka pinkeye
- Moraxella bovis
- UV, dust and flies increase risk
- Tx: topical antibiotics
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- Perforation
- Occasionally ulceration can lead to perforation
- Protruding mass out of eye is usually iris prolapse
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- Uveitis
- C/S: red eye; pupil constriction; cloudy eye; iris reddening
- Recognise early and treat aggressively
- Not that common
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Causes of uveitis
- Traumatic (especially if unilateral)
- Infectious: especially cats (FIV/FeLV/FIP/toxo)
- Lens induced: cataract or lens luxation
- Systemic: neoplasia or autoimmune
- Mostly idiopathic
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Glaucoma
- More common than uveitis
- Raised intraocular pressure (measured by tonopen or schiotz tonometer) is diagnostic
- Ophthalmic emergency
- 72 hours to permanent blindness
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Clinical signs of glaucoma
- Ocular pain
- Blindness in affected eye
- Episcleral congestion - red eye
- Corneal oedema (steamy cornea)
- Mydriasis (dilated pupil)
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Causes of glaucoma
- Inherited or primary (goniodysgenesis): defect in drainage angle - treat both eyes
- Secondary:
- lens luxation
- chronic uveitis
- intraocular neoplasia
- May occur simultaneously with uveitis
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- Lens luxation
- Common in middle aged terriers
- Often present with corneal oedema and secondary glaucoma
- Tx: surgical lens extraction saves vision
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Cataract
- Clouding of lens due to changing protein content
- Ddx: Dogs >9yo have some degree of lens clouding but can see through it. Cataracts opaque
- Common causes:
- inherited
- metabolic (diabetes mellitus)
- Others: age, secondary to intraocular disease, traumatic
- Tx: referral surgery only option
- Sx: $3000 unilateral, $4-4500 both eyes
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- Retinal detatchment
- Old cats - associated with hypertension
- Looks like curtain in back of eye
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Inherited retinal disease
- Most common in dogs: Progressive retinal atrophy (PRA)
- PRA seen in middle aged breeds esp Labs & spaniels
- Leads to gradual deterioration of vision
- Other disease includes:
- collie eye anomoly
- retinal dysplasia
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Sudden onset blindness
- Cats: most commonly is retinal detachment due to systemic hypertension
- Dogs: most commonly is Sudden Acquired Retinal Degeneration (SARDs) - middle aged dogs
- Rare in horses and production animals
- Refer
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