Glaucoma DX and Management Flashcards
What’s the cause of glaucoma in dogs?
Narrow angle glaucoma.
Humans is open angle glaucoma.
Acute glaucoma
diffuse corneal edema, episcleral injection, BIG pupil, sluggish or non-responsive to light stimulation, and signs of ocular PAIN including blepharospasm and epiphora
vision variable
Chronic glaucoma
buphthalmos, Haab’s Striae, lens subluxation, cataract, peripapillary tapetal hyperreflectivity or hyperpigmentation, and optic nerve cupping/atrophy
How are cats different from dogs in gluacoma presentation?
more insidious onset, more resistant to pressure damage, rarely exhibit discomfort
cats with buphthalmos can retain vision while dogs rarely keep it
Most important DDX for glaucoma
- Uveitis
- Diffuse corneal edema due to endothelial dystrophy/degeneration
- Scleritis
- Exophthalmos
Normal pressure in the eye
10-20 mmHg – suspect glaucoma >25 mmHg or if disparity between eyes > 7mmHg
What is gonioscopy useful for?
Determining primary vs. secondary glaucoma. Primary will be narrow angle glaucoma
Is there a cure for glaucoma?
NOPE
Goals of glaucoma therapy
- Preserving vision
- Patient comfort
- Prophylaxis to slow the other eye’s degeneration
Medications used in glaucoma therapy
- Hyperosmotics (mannitol or glycerin)
- Carbonic Anhydrase Inhibitors
- Miotics
- Prostaglandin analogs (best!)
- Beta-blockers
When are hyperosmotics contraindicated?
- Heart failure patients
- dehydrated patients
- Renal Failure patients
When are CAI’s contraindiacted?
May cause GI upset, lethargy, panting, hypokalemia and rarely neurologic symptoms
When are miotics contraindicated?
- Presence of anterior lens luxation
- May exacerbate uveitis
- Demecarium bromide should NOT be used in cats
When are prostaglandin analogs contraindicated?
- Presence of anterior lens luxation
2. May exacerbate uveitis
When are beta-blockers contraindicated?
May cause decreased heart rate in small dogs
Surgical methods of managing glaucoma?
cyclophotocoagulation - laser
gonioimplantation - shunt
TX of Acute Glaucoma/Initial Dx
- IOP measure and check for presence of Vision
- IOP > 35mmHg indicates EMERGENCY (Topical Prostaglandin twice w/in 5 min then mannitol if not reduced)
- CAI and Beta adrenergic can be started concurrently
- Referral for surgery discussed.
TX of Controlled Glaucoma/maintenance therapy
Early surgical measures tend to improve IOP control and stability.
Carbonic anhydrase inhibitors seem most effective and should be the mainstay of treatment.
Resist the temptation to wean animals off of medications if they appear to be doing well.
If IOP seems stable, monthly IOP rechecks are appropriate.
The owner should be instructed to monitor for clinical signs indicating an IOP elevation .
TX of IOP spikes in previously controlled cases
If a significant spike occurs (i.e. IOP >35 mmHg), hyperosmotic medication or topical application of a prostaglandin analogue to rapidly reduce IOP is indicated
Initial recheck of IOP should be within 1 week of re-establishing IOP control and then weekly until IOP stability is confirmed
TX of End stage/Absolute glaucoma
Salvage procedures (enucleation, evisceration with intrascleral prosthesis, or intravitreal gentamicin injection)
Unfortunately, although glaucoma can often be controlled in the short-term, the long-term prognosis for vision retention is poor.
If IOP is high, you must assume the animal is uncomfortable
TX of Eyes at risk of glaucoma (i.e. not yet affected)
Canine primary glaucoma is a bilateral disease
Miotic medications offer the most promise for delaying onset of disease.
Demecraium Bromide
Prostaglandins can work too but expensive.
