Glaucoma Review and Managment Flashcards
What is glaucoma?
-Multifactorial disease
-Elevation of intraocular pressure incompatible with ocular health
-causes irreversible vision loss through optic nerve and ganglion cell death
Where is aqueous humor produced?
Ciliary Body
Where does aqueous humor flow after being produced by the ciliary body?
Through the pupil to the anterior chamber
Where does aqueous humor exit?
through the two drainage pathways
What physiologic dynamics have to be occurring to keep normal intraocular pressure?
Production of AH must equal the outflow of AH
What is primary glaucoma?
Heritable/breed related abnormality of aqueous drainage angle
What is secondary galucoma?
Numerus causes of drainage angle obstruction
-Lense luxation, uveitis, hyphemia, intraocular neoplasia, melanocytic glaucoma, pigmentary uveitis, pseudophakia/aphakia, trauma
What are some causes of feline glaucoma?
Primary: rare - Persian, Siamese and Burmese
Secondary: Similar to dogs, uveitis, aqueous humor misdirection
What are the mechanisms of vision loss in glaucoma?
High IOP
Optic Nerve Ischemia
Neurotoxic Event
Is glaucoma painful?
Yes
What are some clinical signs of glaucoma?
Acute: Blepharospasm, corneal edema, episcleral injection, dilated pupil, variable vision
Chronic: Acute possible, buphthalmos, Haabs striae (Strech), Lense subluxation, cupped optic nerve
How do you diagnose glaucoma?
Clinical signs - cloudy eye, haabs stria, fractures in desmet membrane
History and signalment - breed (basset and spaniel)
IOP measurement (tonometry) 15-25 normal - higher glaucoma
Gonioscopy (specialist)
Bupthalmus = glaucoma issue
What is tonometry?
Measure IOP
*Always do both eyes, normal is 10-25, stress can increase it *
-Acceptable methods: Rebound, applanation, indentation
-Absolute too high or disparities between the 2
(Changes through day)
What is tonometry used for?
-Primary way to diagnose glaucoma and decide therapy
-IOP varies greatly day to day
-Not helpful for early detection (not a yearly thing)
What is Gonioscopy?
-Examination of the drainage angle of the eye
-Need a special lens
- Determine likelyhood of primary glaucoma
What are the goals of treatment for glaucoma?
Maintenace of vision if possible
-buphthalmic - no visual potential (chronic)
Patient comfort
Prophylaxis in at risk eye
What effects your management approach?
Etiology of glaucoma
Current IOP
Presents/Absence of vision
Stage of Disease
What are the 3 main categories of treatment?
Emergency therapy
Maintenance therapy
End-stage/salvage procedure
What classes of drugs can be used to treat glaucoma?
Systemic hyperosmotic medications
carbonic anhydrase inhibitors
miotics
prostaglandin analogue
B-adrenergic blocking agents
What should you do for emergency management of glaucoma?
Topical Iatanoprsot (Xalatan)
-1-2 doses topically 5 min apart, rapid onset of action, convenient
-Prostaglandin analogue
-Only use if Lense not in anterior chamber
Systemic hyperosmotic medication
-IV mannitol or oral glycerin
-quick acting, short response, no use if cardiovascular issue, inferior to topical prostaglandin
What do you treat with for maintenance of Glaucoma?
Carbonic Anhydrase Inhibitors (CAIs)
-most useful - effective and safe in all species
-topical and systemic available
Dorzolamide (trustopt) - TID
Brinxolamide (Azopt) - TID
-Can cause local irritation but no systemic side effect
Mitotics
prostaglandins vs other, moderatly effective, dont use in glaucoma secondary to uveitis or anterior lense lucxation, ocular side effects, good prophylaxis
-Demecarium bromide BID
-Pilocarpine QID
Prostaglandin Analogues
-Latanoprost (xalatan)
-Travoprost (Travatan)
-Bimatoprost (lumigan)
(not helpful in cat)
B-Blockers (topical)
-Mild/moderate effect, not enough as sole agent, prophylaxis, bradycardia and harm asthma
-Timolol maleate
-Betaxolol
Combo drugs
-Dorzolamide-timolol (cosopt)
Which glaucoma medication class is not useful in cats?
Prostaglandin Analoguse
Which glaucoma treatment is safe and effective for all species?
Carbonic Anydrase Inhibitors
Which drug class should you avoid in glaucoma secondary to uveitis or anterior lens luxaiton?
Miotics
Which drug class should be avoided in bradycardia or may worsen asthma?
B- Blockers
What are the general treatment principles for glaucoma?
-Treat aggressively early
-Don’t taper medications in apparently well controlled cases
-Consider surgical intervention if possible in early in disease
How should you follow up with your glaucoma case?
Daily/weekly recheck until IOP control established
-Recheck 3-4 weeks after
-Check IOP every 4-6 weeks in eye at risk of glaucoma
-Owner education and observation critical
What is the target IOP for glaucoma patients?
Dont even want a high normal
<15-20mmHg ideal
(IOP fluxuates so don’t rely on IOP reading)
What medications should you administer for medical prophylaxis?
-Delay in onset of primary glaucoma in second eye
-medications- topical miotitc benefit, CAI and B-blocker, adjunctive topical corticosteroids
What other medical treatment considerations should be taken?
Manage concurrent ocular disease
Topical mydriatics (atropine) are contraindicated - dont dilate the eye when high pressure
What can be done surgically to manage glaucoma?
Decrease Aqueous Production
-Cyclodestructive procedure
-Cyclophotocoagulation
-Cyclocryotherphy
Increase aqueous outflow - shunt/gonioimplants
Combination procedure
What is the prognosis for glaucoma?
Long-term visual prognosis is poor
- go blind in several months, surgical intervention prolongs vision but doesn’t cure it
Salvage surgical procedures - irreversibly blin eyes
What are some salvage procedures that could be performed?
Enucleation, Evisceration/intrascleral prothesis
Chemical ciliary body ablation
What drug is used for chemical ciliary body ablation?
Intravitreal gentamicin injection with steroid (blind eye only, avoid Lense puncture, outcome unpredictable)
