Glaucoma DX and Management

Question 1

What’s the cause of glaucoma in dogs?

Answer 1

Narrow angle glaucoma.

Humans is open angle glaucoma.

Question 2

Acute glaucoma

Answer 2

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

Question 3

Chronic glaucoma

Answer 3

buphthalmos, Haab’s Striae, lens subluxation, cataract, peripapillary tapetal hyperreflectivity or hyperpigmentation, and optic nerve cupping/atrophy

Question 4

How are cats different from dogs in gluacoma presentation?

Answer 4

more insidious onset, more resistant to pressure damage, rarely exhibit discomfort

cats with buphthalmos can retain vision while dogs rarely keep it

Question 5

Most important DDX for glaucoma

Answer 5

1. Uveitis
2. Diffuse corneal edema due to endothelial dystrophy/degeneration
3. Scleritis
4. Exophthalmos

Question 6

Normal pressure in the eye

Answer 6

10-20 mmHg – suspect glaucoma >25 mmHg or if disparity between eyes > 7mmHg

Question 7

What is gonioscopy useful for?

Answer 7

Determining primary vs. secondary glaucoma. Primary will be narrow angle glaucoma

Question 8

Is there a cure for glaucoma?

Answer 8

NOPE

Question 9

Goals of glaucoma therapy

Answer 9

1. Preserving vision
2. Patient comfort
3. Prophylaxis to slow the other eye’s degeneration

Question 10

Medications used in glaucoma therapy

Answer 10

1. Hyperosmotics (mannitol or glycerin)
2. Carbonic Anhydrase Inhibitors
3. Miotics
4. Prostaglandin analogs (best!)
5. Beta-blockers

Question 11

When are hyperosmotics contraindicated?

Answer 11

1. Heart failure patients
2. dehydrated patients
3. Renal Failure patients

Question 12

When are CAI’s contraindiacted?

Answer 12

May cause GI upset, lethargy, panting, hypokalemia and rarely neurologic symptoms

Question 13

When are miotics contraindicated?

Answer 13

1. Presence of anterior lens luxation
2. May exacerbate uveitis
3. Demecarium bromide should NOT be used in cats

Question 14

When are prostaglandin analogs contraindicated?

Answer 14

1. Presence of anterior lens luxation

2. May exacerbate uveitis

Question 15

When are beta-blockers contraindicated?

Answer 15

May cause decreased heart rate in small dogs

Question 16

Surgical methods of managing glaucoma?

Answer 16

cyclophotocoagulation - laser

gonioimplantation - shunt

Question 17

TX of Acute Glaucoma/Initial Dx

Answer 17

1. IOP measure and check for presence of Vision
2. IOP > 35mmHg indicates EMERGENCY (Topical Prostaglandin twice w/in 5 min then mannitol if not reduced)
3. CAI and Beta adrenergic can be started concurrently
4. Referral for surgery discussed.

Question 18

TX of Controlled Glaucoma/maintenance therapy

Answer 18

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 .

Question 19

TX of IOP spikes in previously controlled cases

Answer 19

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

Question 20

TX of End stage/Absolute glaucoma

Answer 20

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

Question 21

TX of Eyes at risk of glaucoma (i.e. not yet affected)

Answer 21

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.