The Blind Eye Flashcards
What are some common causes of blindness?
Symblepharon Keratitis Persistent pupillary membranes Uveal problems Cataracts Glaucoma Fundic disease
What is symblepharon?
Two layers stuck together:
Conjunctiva and cornea
Eyelid and cornea
Eyelid and conjunctiva
What is a key cause of symblepharon in kittens/cats ?
What is the general pathogenesis?
FHV type I
Causes ulceration of the conjunctiva and cornea
- wounds stick together and create adhesions
(Uncommon)
What type of keratitis is common in brachys?
Pigmentary keratopathy
- pigment on cornea
- occurs secondary to entropion, distichiasism, eurynlepharon
What is euryblepharon?
Large palpebral fissure
What is lagopthalmus?
inability to close eyelid completely
How do you treat patients with pigmentary keratopathy due to brachycephalic ocular syndrome?
Surgical correction of euryblepharon (etc)
What is the pupillary membrane
Embryologic membrane that should regress
Originates from iris colarette
BVs which emerge from middle part of iris and nourish lens during development
What can PPMs cause?
Corneal and/or lens opacity
What clinical signs are associated with uveitis?
FLARE - Tyndall effect
Hypopion +/ hyphaema
Synechia - adhesions between iris and cornea or lens
DECREASED IOP - can increase if chronic
Why do you see reduced IOP in patients with acute uveitis?
Ciliary body doesn’t produce as much aqueous humour
What is the uvea?
All the vascular tissue in the eye
- iris and ciliary body - anterior
- choroid - posterior
What causes flare?
Increased proteins in the anterior chamber
Does hypopion always indicate infection?
NO
Usually STERILE
What is the difference between anterior and posterior synechia?
Anterior - iris adheres to cornea
Posterior - iris adheres to lens
How can you differentiate between PPMs and synechia ?
PPM - originates from iris colarette (middle segment)
Synechia - comes from margin of iris
What complications can occur due to uveitis?
Why?
Corneal oedema - damage to endothelium which usually pumps out fluid
Cataracts - poor nourishment to lens
Synechia
Retinal detachment - inflammation of choroid
Lens luxation in cats
Glaucoma - accumulation of inflammatory cells etc
What causes uveal problems ?
- systemic hypertension
- infectious
- immune mediated
- neoplastic
- complicated ulcers
What are some infectious causes of uveitis?
Viral - FeLV, FIV, FIP
Bacterial - pyo and others e.g. cystitis
Parasitic - Toxoplasma, Leishmania
Fungal- Cryptococcus (not common)
What neoplasms can cause uveitis?
Lymphoma MOST COMMON
Metastatic adenocarcinoma
What is reflex uveitis ?
CNV irritated causing epiphora and reflex cascade leading to uveitis
What is the most common cause of uveal problems?
What is the suggested tx ?
Idiopathic
Immunosuppressive therapy
When can you use steroids?
If corneal ulcer has been RULED OUT
What opthalmic findings would you expect with systemic hypertension?
Intraocular haemorrhage
Bullous retinal detachment
Iris earl haemorrhages
Tortuosity of retinal vessels (don’t look as straight)
What is a cataract?
Any opacity of the lens which impedes light transmission
How are cataracts related to uveitis?
Can cause uveitis
Can be a sequel to uveitis due to poor lens nourishment
What is the difference between cataracts and nuclear sclerosis?
Nuclear sclerosis isn’t associated with visual defects - can still see through it on fundoscopy
Aging change that generally does NOT cause blindness
Which cataracts cause blindness?
Complete
What are the causes of cataracts?
Inherited Congenital Traumatic Metabolic Nutritional PRA Senile
How do traumatic cataracts tend to occur?
Blunt trauma (compression of eye) or penetrating trauma (FB or scratch)
How can phacoclastic uveitis occur secondary to FB trauma?
How is it treated?
FB opens up lens capsule leading to leakage of lens protein into the anterior chamber and expose it to the immune system.
Difficult to control medically - Lens removal usually indicated - REFERRAL
What causes metabolic cataracts?
DIABETES in DOGS (rare for cats)
Describe the appearance of senile cataracts
Cortex (periphery)
Wedge shaped
Rarely progress to complete cataract
What should you do to relieve pain in end stage glaucoma?
REMOVE EYE
What are some key retinal diseases?
Retinal dysplasia
PRA
Retinal toxicity - high dose enrofloxacin in cats
Acute retinal disease - SARDS, IMR
What breed is typically affected by retinal dysplasia?
SPANIELS
CKCS ESS
Congenital
What is PRA?
What CS is it associated with
Progressive Retinal Atrophy
Night blindness progress to day blindness
Leads to cataract (end stage)
Not painful
What is associated with PRA on opthalmic examination?
Hyperreflective Tapetum - retinal thinning
Vascular attenuation - retinal vessel thinning
Late stage: cataracts
What is retinal detachment?
What are the two types?
Neuro-retina detaches from retinal pigment epithelium
INFLAMMATORY = BULLOUS
DISINSERTIONAL = RHEGMATOGNOUS
What causes bullous retinal detachment?
Retina is pushed by fluid
What causes rhegmatogenous retinal detachment ?
Retina loses peripheral attachments
What are the clinically significant optic nerve diseases?
Optic neuritis
Optic nerve neoplasia
What causes optic neuritis?
Meningoencephalitis of known origin / aetiology(MUO/A)
Infectious diseases
- Distemper
- Ehrlichia
- Cryptococcus
What is the most common neoplasia of the optic nerve?
MENINGIOMA
How can you identify optic neuritis
Hyperaemia of the papilla
Vascular congestion
Peri papillary haemorrhages
