Glaucoma

Question 1

What is glaucoma?

Answer 1

Increased intraocular pressure (IOP)

Question 2

How does the aqueous humor flow though the eye?

Answer 2

Ciliary body —> posterior chamber —> pupil —> anterior chamber —> iridoconreal angle —> venous drainage

Question 3

What enzyme is responsible for active secretion of aqueous humor?

Answer 3

Carbonic anhydrase

Question 4

T/F: glaucoma is almost always due to impaired outflow

Answer 4

True

— iridocorneal angle
— uveoscleral

Question 5

Acute clinical signs of glaucoma?

Answer 5

Red eye — episceral injection 
Blepharospasm 
Corneal edema 
Mydriasis 
Impaired vision

Question 6

Chronic clinical signs of glaucoma?

Answer 6

Optic disc cupping

Retinal degeneration

Irreversible blindness

Buphthalmos

Lens changes — Haabs striae (cracks in desmenths membrane)
Lens luxation

Phthisis bulbi — shrunken eye, end strange

Question 7

What factors do you base your prognosis for vision on in a case of glaucoma?

Answer 7

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)

Question 8

At what IOP can you confirm glaucoma?

Answer 8

> 20mmHg or >20% difference between eyes is suspicious for glaucoma

> 25-27mmHg with clinical signs is sufficient for diagnosis of glaucoma

Question 9

What are the primary causes of glaucoma?

Answer 9

Primary angle closure glaucoma — goniodysgenesis (most common)

Primary open angle glaucoma

Question 10

Breeds predisposed to primary angle closure glaucoma?

Answer 10

Cocker spaniels, basset hounds

Females > males

Middle aged to older

Question 11

Breed predisposed to primary open angle glaucoma

Answer 11

Beagle

Question 12

What are causes of secondary glaucoma?

Answer 12

Associated with other ocular or systemic abnormalities

Uveitis
Neoplasia
Lens luxation

Question 13

How do you diagnose a primary glaucoma?

Answer 13

Lack of uveitis
Lack of intraocular tumors
Lack of lens luxation
Appropriate signalment

Goinosocpy — examin iridocorneal angle (referral procedure)

Question 14

T/F: Primary angle glaucoma attacks are associated with stress, excitement, and dim light

Answer 14

True

Question 15

T/F: primary angle glaucoma is usually unilateral disease

Answer 15

False

Initially unilateral but becomes bilateral

Question 16

What is the most effective therapy for primary glaucoma in canines?

Answer 16

Lantanoprost

— topical prostaglandin derivative

Increases uveoscleral outflow
Potent miotic increases drainage angle

Question 17

Side effects to lantanoprost?

Answer 17

Topical irritation, uveitis

Question 18

When is lantanoprost contraindicated?

Answer 18

Secondary glaucoma due to uveitis
Lens luxation

Not effective in most forms of feline glaucoma

Question 19

What is the most effective therapy for glaucoma in cats and horses?

Answer 19

Dorzolamide

Carbonic anhydrase inhibitor
— decrease aqueous production

Question 20

How do you treat pressure induced ischemia and inflammation in a glaucoma case?

Answer 20

Neo/poly/Dex

Prednisolone acetate

Question 21

If both lantanoprost and dorzolamide are ineffective at reducing glaucoma, what can you use?

Answer 21

mannitol IV

Hyperosmoic

Question 22

What surgical therapies can treat glaucoma?

Answer 22

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

Question 23

What prophylactic therapy can you use in the contralateral eye to prevent onset of glaucoma

Answer 23

Betaxolol
- increased chance of KCS

Demarcarium bromide

• can cause uveitis
• use in combo with topical steroid

Timolol

Question 24

What are the treatment options for end-stage glaucoma ? And when is it indicated?

Answer 24

Enucleation
Evisceration and prosthesis
Ciliary body ablation

Blind and painful eyes

Question 25

What is usually the primary presenting sign in feline glaucoma?

Answer 25

Mydriasis

Almost always due to uveitis