Glaucoma Review and Managment

Question 1

What is glaucoma?

Answer 1

-Multifactorial disease
-Elevation of intraocular pressure incompatible with ocular health
-causes irreversible vision loss through optic nerve and ganglion cell death

Question 2

Where is aqueous humor produced?

Answer 2

Ciliary Body

Question 3

Where does aqueous humor flow after being produced by the ciliary body?

Answer 3

Through the pupil to the anterior chamber

Question 4

Where does aqueous humor exit?

Answer 4

through the two drainage pathways

Question 5

What physiologic dynamics have to be occurring to keep normal intraocular pressure?

Answer 5

Production of AH must equal the outflow of AH

Question 6

What is primary glaucoma?

Answer 6

Heritable/breed related abnormality of aqueous drainage angle

Question 7

What is secondary galucoma?

Answer 7

Numerus causes of drainage angle obstruction
-Lense luxation, uveitis, hyphemia, intraocular neoplasia, melanocytic glaucoma, pigmentary uveitis, pseudophakia/aphakia, trauma

Question 8

What are some causes of feline glaucoma?

Answer 8

Primary: rare - Persian, Siamese and Burmese
Secondary: Similar to dogs, uveitis, aqueous humor misdirection

Question 9

What are the mechanisms of vision loss in glaucoma?

Answer 9

High IOP
Optic Nerve Ischemia
Neurotoxic Event

Question 10

Is glaucoma painful?

Answer 10

Yes

Question 11

What are some clinical signs of glaucoma?

Answer 11

Acute: Blepharospasm, corneal edema, episcleral injection, dilated pupil, variable vision

Chronic: Acute possible, buphthalmos, Haabs striae (Strech), Lense subluxation, cupped optic nerve

Question 12

How do you diagnose glaucoma?

Answer 12

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

Question 13

What is tonometry?

Answer 13

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)

Question 14

What is tonometry used for?

Answer 14

-Primary way to diagnose glaucoma and decide therapy
-IOP varies greatly day to day
-Not helpful for early detection (not a yearly thing)

Question 15

What is Gonioscopy?

Answer 15

-Examination of the drainage angle of the eye
-Need a special lens
- Determine likelyhood of primary glaucoma

Question 16

What are the goals of treatment for glaucoma?

Answer 16

Maintenace of vision if possible
-buphthalmic - no visual potential (chronic)
Patient comfort
Prophylaxis in at risk eye

Question 17

What effects your management approach?

Answer 17

Etiology of glaucoma
Current IOP
Presents/Absence of vision
Stage of Disease

Question 18

What are the 3 main categories of treatment?

Answer 18

Emergency therapy
Maintenance therapy
End-stage/salvage procedure

Question 19

What classes of drugs can be used to treat glaucoma?

Answer 19

Systemic hyperosmotic medications
carbonic anhydrase inhibitors
miotics
prostaglandin analogue
B-adrenergic blocking agents

Question 20

What should you do for emergency management of glaucoma?

Answer 20

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

Question 21

What do you treat with for maintenance of Glaucoma?

Answer 21

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)

Question 22

Which glaucoma medication class is not useful in cats?

Answer 22

Prostaglandin Analoguse

Question 23

Which glaucoma treatment is safe and effective for all species?

Answer 23

Carbonic Anydrase Inhibitors

Question 24

Which drug class should you avoid in glaucoma secondary to uveitis or anterior lens luxaiton?

Answer 24

Miotics

Question 25

Which drug class should be avoided in bradycardia or may worsen asthma?

Answer 25

B- Blockers

Question 26

What are the general treatment principles for glaucoma?

Answer 26

-Treat aggressively early -Don't taper medications in apparently well controlled cases -Consider surgical intervention if possible in early in disease

Question 27

How should you follow up with your glaucoma case?

Answer 27

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

Question 28

What is the target IOP for glaucoma patients?

Answer 28

Dont even want a high normal <15-20mmHg ideal (IOP fluxuates so don't rely on IOP reading)

Question 29

What medications should you administer for medical prophylaxis?

Answer 29

-Delay in onset of primary glaucoma in second eye -medications- topical miotitc benefit, CAI and B-blocker, adjunctive topical corticosteroids

Question 30

What other medical treatment considerations should be taken?

Answer 30

Manage concurrent ocular disease Topical mydriatics (atropine) are contraindicated - dont dilate the eye when high pressure

Question 31

What can be done surgically to manage glaucoma?

Answer 31

Decrease Aqueous Production -Cyclodestructive procedure -Cyclophotocoagulation -Cyclocryotherphy Increase aqueous outflow - shunt/gonioimplants Combination procedure

Question 32

What is the prognosis for glaucoma?

Answer 32

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

Question 33

What are some salvage procedures that could be performed?

Answer 33

Enucleation, Evisceration/intrascleral prothesis Chemical ciliary body ablation

Question 34

What drug is used for chemical ciliary body ablation?

Answer 34

Intravitreal gentamicin injection with steroid (blind eye only, avoid Lense puncture, outcome unpredictable)