Glaucoma

Question 1

What does increase in IOP lead to?

Answer 1

Damages retina and optic nerve

Question 2

T/F

Glaucoma is the leading cause of retinal detachment in the middle aged dog

Answer 2

False

leading cause of blindness

Question 3

How long do you have to save vision in a dog with glaucoma?

Answer 3

48 hours

Question 4

Where is the iridocorneal angle located?

Answer 4

Between iris and cornea

Question 5

How is aqueous humor produced and drained? What is the path it takes?

Answer 5

Produced by ciliary body –> flows b/w lens and iris through pupil –> out ICA b/w iris and cornea

Question 6

What can cause glaucoma?

Answer 6

Any part of the aqueous humor flow blocked

Question 7

What is seen with acute glaucoma?

Answer 7

Elevated IOP
Red eye
Vision loss
corneal edema
Mydriasis

Question 8

Three characteristic signs of chronic glaucoma

Answer 8

1. Buphthalmos
2. Haab’s striae
3. Lens subluxation

Question 9

What is Haab’s striae?

Answer 9

Gray line across eye

seen when descemets membrane snaps

Question 10

What are some ways we evaluate eye pressure?

Answer 10

Schiotz Tonometer
Tonopen
Tonovet

Question 11

What is Gonioscopy?

Answer 11

Examination of the opening into the ciliary cleft (drainage angle)

Question 12

What is the medical term for what causes primary glaucoma? Define it

Answer 12

Goniodysgenesis - ICA didn’t form properly

Question 13

Breeds that are pre-disposed to primary glaucoma

Answer 13

Cocker Spaniel
Basset Hound
Terriers
Springer spaniel
Great Dane
Siberian Husky
Samoyed
Bouvier des Handres

Question 14

What causes secondary glaucoma?

Answer 14

Sequelae to:
Melanoma
Pink eye in cattle
Chronic RU in horse
Lens luxation
Uveitis (iris bombe or cells creating plug)

Question 15

Where is the posterior chamber of the eye?

Answer 15

Between lens and back of the iris

Question 16

There is a conventional outflow track and an unconventional outflow track for AH… what are they?

Answer 16

Conventional - ICA

Unconventional - uveoscleral pathway

Question 17

What percentage of outflow is from the ICA in horses, cats, and dogs?

Answer 17

Horses - 50%
Dogs - 85%
Cats - 97%

Question 18

What are two mechanisms causing mydriasis with glaucoma?

Answer 18

1. optic nerve is not functioning –> no light input leaves eye to stimulate pupil to constrict
2. elevated IOP –> ischemia to iris sphincter muscle –> can’t constrict. Increase IOP is also pushing pupil open

Question 19

What are some ways IOP is falsely elevated?

Answer 19

• struggling patient
• collar is too tight
• tight restraint around neck
• pushing on globe while attempting to open eyelids

Question 20

What type of procedure is pharmacologic ciliary body ablation? What patient is this used for?

Answer 20

Salvage procedure

Cure for chronic cases

Question 21

Explain the pharmacologic ciliary body ablation procedure

Answer 21

Inject gentamicin with dexamethasone into the vitreous body

Question 22

What are risks of the pharmacologic ciliary body ablation procedure?

Answer 22

1. Toxic to retina – only use in blind patients!
2. Can cause phthisis bulbi
3. Ciliary body may regenerate
4. May hit lens –> phacoclastic uveitis that will require enucleation

Question 23

What pressure is usually painful?

Answer 23

30mmHg