Glaucoma Flashcards
(23 cards)
What does increase in IOP lead to?
Damages retina and optic nerve
T/F
Glaucoma is the leading cause of retinal detachment in the middle aged dog
False
leading cause of blindness
How long do you have to save vision in a dog with glaucoma?
48 hours
Where is the iridocorneal angle located?
Between iris and cornea
How is aqueous humor produced and drained? What is the path it takes?
Produced by ciliary body –> flows b/w lens and iris through pupil –> out ICA b/w iris and cornea
What can cause glaucoma?
Any part of the aqueous humor flow blocked
What is seen with acute glaucoma?
Elevated IOP Red eye Vision loss corneal edema Mydriasis
Three characteristic signs of chronic glaucoma
- Buphthalmos
- Haab’s striae
- Lens subluxation
What is Haab’s striae?
Gray line across eye
seen when descemets membrane snaps
What are some ways we evaluate eye pressure?
Schiotz Tonometer
Tonopen
Tonovet
What is Gonioscopy?
Examination of the opening into the ciliary cleft (drainage angle)
What is the medical term for what causes primary glaucoma? Define it
Goniodysgenesis - ICA didn’t form properly
Breeds that are pre-disposed to primary glaucoma
Cocker Spaniel Basset Hound Terriers Springer spaniel Great Dane Siberian Husky Samoyed Bouvier des Handres
What causes secondary glaucoma?
Sequelae to: Melanoma Pink eye in cattle Chronic RU in horse Lens luxation Uveitis (iris bombe or cells creating plug)
Where is the posterior chamber of the eye?
Between lens and back of the iris
There is a conventional outflow track and an unconventional outflow track for AH… what are they?
Conventional - ICA
Unconventional - uveoscleral pathway
What percentage of outflow is from the ICA in horses, cats, and dogs?
Horses - 50%
Dogs - 85%
Cats - 97%
What are two mechanisms causing mydriasis with glaucoma?
- optic nerve is not functioning –> no light input leaves eye to stimulate pupil to constrict
- elevated IOP –> ischemia to iris sphincter muscle –> can’t constrict. Increase IOP is also pushing pupil open
What are some ways IOP is falsely elevated?
- struggling patient
- collar is too tight
- tight restraint around neck
- pushing on globe while attempting to open eyelids
What type of procedure is pharmacologic ciliary body ablation? What patient is this used for?
Salvage procedure
Cure for chronic cases
Explain the pharmacologic ciliary body ablation procedure
Inject gentamicin with dexamethasone into the vitreous body
What are risks of the pharmacologic ciliary body ablation procedure?
- Toxic to retina – only use in blind patients!
- Can cause phthisis bulbi
- Ciliary body may regenerate
- May hit lens –> phacoclastic uveitis that will require enucleation
What pressure is usually painful?
30mmHg
