Glaucoma Flashcards
What is glaucoma?
Increased intraocular pressure (IOP)
How does the aqueous humor flow though the eye?
Ciliary body —> posterior chamber —> pupil —> anterior chamber —> iridoconreal angle —> venous drainage
What enzyme is responsible for active secretion of aqueous humor?
Carbonic anhydrase
T/F: glaucoma is almost always due to impaired outflow
True
— iridocorneal angle
— uveoscleral
Acute clinical signs of glaucoma?
Red eye — episceral injection Blepharospasm Corneal edema Mydriasis Impaired vision
Chronic clinical signs of glaucoma?
Optic disc cupping
Retinal degeneration
Irreversible blindness
Buphthalmos
Lens changes — Haabs striae (cracks in desmenths membrane)
Lens luxation
Phthisis bulbi — shrunken eye, end strange
What factors do you base your prognosis for vision on in a case of glaucoma?
Acute vs chronic — duration of signs over a day decreases prognosis
Buphthalmic —bind
Bupthalmia vs exophthalmia
—> check IOP
—> check corneal diameter (larger with buphthalmia)
—> lens luxation (secondary with bupthamia)
At what IOP can you confirm glaucoma?
> 20mmHg or >20% difference between eyes is suspicious for glaucoma
> 25-27mmHg with clinical signs is sufficient for diagnosis of glaucoma
What are the primary causes of glaucoma?
Primary angle closure glaucoma — goniodysgenesis (most common)
Primary open angle glaucoma
Breeds predisposed to primary angle closure glaucoma?
Cocker spaniels, basset hounds
Females > males
Middle aged to older
Breed predisposed to primary open angle glaucoma
Beagle
What are causes of secondary glaucoma?
Associated with other ocular or systemic abnormalities
Uveitis
Neoplasia
Lens luxation
How do you diagnose a primary glaucoma?
Lack of uveitis
Lack of intraocular tumors
Lack of lens luxation
Appropriate signalment
Goinosocpy — examin iridocorneal angle (referral procedure)
T/F: Primary angle glaucoma attacks are associated with stress, excitement, and dim light
True
T/F: primary angle glaucoma is usually unilateral disease
False
Initially unilateral but becomes bilateral
What is the most effective therapy for primary glaucoma in canines?
Lantanoprost
— topical prostaglandin derivative
Increases uveoscleral outflow
Potent miotic increases drainage angle
Side effects to lantanoprost?
Topical irritation, uveitis
When is lantanoprost contraindicated?
Secondary glaucoma due to uveitis
Lens luxation
Not effective in most forms of feline glaucoma
What is the most effective therapy for glaucoma in cats and horses?
Dorzolamide
Carbonic anhydrase inhibitor
— decrease aqueous production
How do you treat pressure induced ischemia and inflammation in a glaucoma case?
Neo/poly/Dex
Prednisolone acetate
If both lantanoprost and dorzolamide are ineffective at reducing glaucoma, what can you use?
mannitol IV
Hyperosmoic
What surgical therapies can treat glaucoma?
If eye is visual
- increase aqueous outflow (gonioimpant) which drains from anterior chamber into SQ
-decrease aqueous production (ciliary body ablation) — trans-scleral or endolaser
What prophylactic therapy can you use in the contralateral eye to prevent onset of glaucoma
Betaxolol
- increased chance of KCS
Demarcarium bromide
- can cause uveitis
- use in combo with topical steroid
Timolol
What are the treatment options for end-stage glaucoma ? And when is it indicated?
Enucleation
Evisceration and prosthesis
Ciliary body ablation
Blind and painful eyes
