The blind eye Flashcards
What are the causes of blindness?
- symblepharon
- keratitis
- uveal disease
- cataracts
- glaucoma?
- posterior segment disease (vitreous, retina)
How can glaucomas cause blindness?
high intraocular pressure
neurodegenrative dz
progressive and ultimately kleads to blindness
What is symblepharon?
condition where there is adhesion of conjunctival tissue to another conjunctival surface or the cornea
mostly seen in kittens and feline herpesvirus type 1
What is pigmentary keratophathy?
pigment on the cornea
secondary to entropion, trichiasis, euryblepharon
common in brachycephalic
What are the clinical signs of uveitis?
flare on tyndall effect
hypopyon (WBC)
hyphema (blood)
synechia (anterior, posterior)
decreased IOP unless chronic (increased)
What are potential causes for hyphema?
don’t assume trauma unless injury observed
lung worm dz
systemic hypertension
immune-mediated thrombocytopenia, coagulopathy, intraocular neoplasia
infectious disease: ehrlichia, leishmaniasis
What are the 2 types of sequelae?
anterior synechia: corneal perforation causing adhesion of the iris to the cornea
posterior synechia: adhesion of iris to the lens
What is persistent pupillary membranes PPMs?
developmental abnormalities that should have regressed
originate strands from the iris collarete
can cause corneal or lens opacity
What are potential complications of uveitis?
- corneal oedema
- cataracts
- synechiae
- pre-iridal fibrovascular membranes
- retinal detachment
- lens luxation
- glaucoma
What are the causes of uveal disease?
- systemic hypertension
- infectious (viral, parasitic, fungal, bacterial)
- immune-mediated
- neoplastic
- complicated ulcers/reflex uveitis
What are primary and secondary causes for uveal disease?
primary: opthalmic causes (complicated ulcer, FB, etc.)
secondary: systemic causes (infl., hypertension, idiopathic, etc.)
How do we treat uveal disease?
TREAT CAUSE
start systemic anti-inflammatories if possible
topical anti-inflammatory tx
What are the systemic non-steroidals and steroids we can give as systemic anti-inflammatory for uveal dz?
non-sterioidal” carprofen, meloxicam
steroid: prednisolone
What are the types of topical anti-inflammatory tx we give for uveal dz?
steroid eye drops: prednisolone acetate, dexamethasone phosphate
cycloplegics: atropine/cyclopentolate
(stop spasms of the ciliary body)
What are the possible ophtalmic findings of animals with hypertension?
intraocular haemorrhage
bullous retinal detatchment
iridal haemorrhages
tortuosity of retinal vessels
What is equine recurrent uveitis (ERU) ?
heterogenous disease
nonspecific immune mediated
leading cause of blindness in horses
peak initial uveitis episode at 4-6y/o
warmbloods, draft, european
What is the signs of classic ERU?
most common type
active inflammatory episodes followed by periods with minimal ocular signs
increasingly severe episodes of uveitis and progress to chronic signs
What are acute classic ERU signs?
miosis
iris hyperaemia/swelling
ocular pain
conjunctival hyperaemia
corneal oedema
fibrin in anterior chamber
What are the chronic signs of classic ERU?
atrophy
granular iridica
fibrosis iris
ICA
hyperpigmentation iris
What are the complications of classic ERU?
cataract
posterior synechia
glaucoma
phthisis bulbi
What are the clinical signs of insidious ERU?
minimal signs of ocular discomfort
low-grade immune response that continues and slowly progresses to chronic clinical signs ERU
appaloosa, draft breed
difficult to dx until severe chronic signs
What are the clinical signs of chronic insidious ERU?
ICA fibrosis
iris fibrosis
cataract formation
conjunctival hyperaemia
iris hyper pigmentation
granula iridica atrophy
synechia formation
What are the clinical signs of posterior ERU?
subtle anterior uveitis (miosis)
vitreal opacities (pond-like reflexion of the vitreous)
retinal inflammation
retinal detachment or degeneration
What is the first and second aim when tx ERU?
first: preserve vision
second: reduce and control ocular inflammation to limit permanent damage to the eye
What are the medical tx for acute ERU cases?
topical steroids/NSAID
atropine
systemic anti-infl.
What are the medical tx for severe chronic ERU cases?
subconjunctival or intravitreal injection steroids
What are the 3 possible surgical tx for ERU?
suprachoroidal cyclosporine implants
pars plana vitrectomy (clears media/remove membranes)
enucleation
What are the 2 ways cataracts can cause uveitis?
phacolytic: leaky lens (lens protein diffuse through intact lens capsule with chronic cataracts)
phacoclastic: ruptured lens (protein gets into eye via rupture of lens capsule)
What are the 2 ways chronic uveitis can cause cataracts?
due to poor nourishment of the lens
altered chemistry of the aqueous humour
What is the difference between direct illumination and retroillumination of cataracts?
direct illumination: cataract will look fully white
retroillumination: shadow/dark from behind the opacity
What type of cataracts interfere with sight and cause blindness?
incipient, immature and mature interfere with sight
mature only will cause blindness
What are the 7 causes for cataracts?
inherited
congenital
traumatic
metabolic
nutritional
progressive retinal atrophy
senile
Where do congenital cataracts form?
always nuclear
What are causes of traumatic cataracts?
FB
cat scratches
What type of uveitis can be induced by traumatic cataracts?
phacoclastic uveitis
tear can cause a FB reaction = need to remove the lens material w/ cataract surgery to stop chronic uveitis
What causes metabolic cataracts?
diabetic cataractogenesis
glucose is small enough to difuse into lens capsule from aqueous humour
its made into sorbitol, too big to leave lens
draws water in w/ osmosis, lens can eventually rupture
What are nutritional causes for cataracts?
uncommon now
puppies and kittens fed inappropriate milk replacementrs, deficiency of essential amino acids
How does progressive retinal atrophy cause cataracts?
secondary to retinal degeneration
degenerating retina releases toxins which cause cataracts
What is often affected with senile cataracts?
the cortex is generally affected
wedge shaped
if small might not occlude vision
What are vitreal diseases causing blindness?
persistent hyaloid artery and primary vitreous
cataracts +/-
What are retinal diseases that can cause blindness?
retinal dysplasia
progressive retinal atrophy
retinal toxicity: high dose enrofloxacin in cats
acute retinal diseases (Sudden acquired retinal degeneration syndrome and immune-mediated retinopathy)
What are the 3 main types of retinal dyplasia and what breeds are prone?
retinal folds
geographic
retinal detachment (severe)
CKCS, ESS
What is progressive retinal atrophy PRA?
inherited degenerative disease of the retina causing night blindness and eventually day blindness
can lead to cataracts but can’t get sx to tx it
What can inidcate progressive retinal atrophy in an ophtalmic examination?
clinical hx
breed
hyperreflective tapetum (thinning of retina)
vascular attenuation (thinning retinal vessels)
late stage: cataracts
What drugs are toxic to retinas in cats?
high dose enrofloxacin
even at current recommended doses
can also cause neuro signs
** all fluoroquinolones to be used with caution but no retinal toxicity is reported w/ pradofloxacin!
How can we diagnose sudden acquired retinal degeneration syndrome SARDS?
acute/subacute vision loss
PLR may or may not be present
ophtalmic exam unremarkable
diagnostic test: electroretinography!! (shows there is no response in retina)
What are the 2 types of retinal detachment?
inflammatory: retina pushed by fluid (bullous, seagull shape)
disindertional: retina loses peripheral attachments (rhegmatogenous)
What are the causes for optic neuritis?
meningoencephalitis of unknown origin/aetiology (MUOA)
infectious dz: distemper, ehrlichia, crypto,…
What is the most common neoplasia of the optic nerve?
meningioma
What are the signs of optic neuritis?
hyperaemia of the papilla
vascular congestion
peripapillary hemorrhages
What is Collie Eye Anomaly (CEA)?
combination of choroidal hypoplasia and optic nerve head coloboma
can develop retinal detachment, hyphema, vitreal haemorrhage
What are the causes of blindness?
glaucoma: high intraocular pressure
eyelid abnormalities: symblepharon
corneal abnormalities: pigmentation
uveal disease: hypopyon, hyphaema
catarcats
retinal and optic nerve diseases
