Glaucoma Flashcards
Glaucoma - what is it?
– Syndrome where increased intraocular pressure is
incompatible with vision
Glaucoma - Pathophysiology
– Impaired drainage of aqueous humour
– Ischemia and hypoxia due to compression
– Cell death from retinal ganglion cells and optic nerve
Congenital glaucoma
– Early form of primary glaucoma or malformation of irido-corneal angle – Any breed or sex – Buphthalmia – Prognosis: grave
Hot breeds for primary glaucoma
cocker, boston, basset, poodle, shar pei, husky, samoyed
primary glaucoma
– Bilateral: • Asynchronous appearance – Irido-corneal angle • closed, narrow or open – Goniodysgenesis • Angle is abnormal www.bostonterrierdog.net www.iwantapounddog.blogspot.com Glaucoma 
Secondary glaucoma
– Lens luxation: TERRIERS
– Uveitis: Iris bombe
– Neoplasia
Clinical signs of acute glaucoma.
Clinical signs: Acute – Diffuse corneal edema – “Red” eye – Dilated fixed pupil – Unilateral – Vision loss
Clinical signs of chronic glaucoma.
Clinical signs: Chronic – Buphthalmia – Exposure keratitis – Corneal striae – Diffuse corneal edema – Fixed dilated pupil – +/- lens luxation – Retinal atrophy – Vision 
Glaucoma tests - 3 instruments
– PLR: indirect
– Fluorescein stain
– IOP
• Schiotz vs Tonopen vs TonoVet
– Proper restraint
– Technical abilityGlaucoma Medical therapy
– Osmotic diuretics – Carbonic Anhydrase Inhibitors – Prostaglandin analogues – Beta adrenergic antagonists – Parasympathomimetics – Sympathomimetics
Primary glaucoma - lens in place. How do you treat?
• Triple cocktail: – Trusopt (carbonic anhydrase inhibitor) – Timolol (beta blocker) – Travatan (prostaglandin analog) IOP in 30-45 mins! (Plan B - mannitol, can do drops after)
Mannitol - how to treat with this
– 1g/kg IV in 20-30 mins
– Withold water for 2-3 hrs
– Repeat 1g/kg if IOP >30mmHg 1 hr post- injection
Secondary glaucoma. How do you treat?
– Trusopt (carbonic anhydrase inhibitor)
– Timolol (beta blocker)
- Coriticosteroids (topical/uveitis)
Aqueocentesis
Very controversial 30 g needle at limbus 1-3 drops of aqueous No syringe avoid iris and lens
Reperfusion Injury with Glaucoma
If the eye has been under pressure for at least 24 hours, then no matter whether you take seconds or minutes, you’ll injure the eye with reprerfusion due to oxidative stress from released radicals.. Amlodipine could possibly help stabilize things (calcium channel blockers) and coriticosteroids, but we don’t have anything really efficacious
Medical management
CAI are great, topical is better than oral
Beta blockers don’t work well in dogs, but can be added.
Prostaglandin analogues are great (big guns) but there are side-effects. Can give too low a pressure.
If you have a primary glaucoma, then the other eye likely has a good risk of glaucoma as well, so you can start it on a bit of medication. You can use Topical CAI and possibly add a topical beta blocker.
Monitoring medical management - how often should you monitor?
Check every hour until within normal range
4-6 hours for 24 hours
Once weekly
When not to use medication (give specific medications and examples of when not to use)
– Mannitol: diabetic, cardiac, renal patients
– Timolol (Beta blocker): cardiac or asthmatic (feline) patients
– Travaprost (prostaglandin analog): uveitis, lens luxation present
– Pilocarpine (parasympathomimetic, old): uveitis, lens luxation present
Surgical treatment
Enucleation Evisceration with intraocular prosthesis Chemical ablation Laser photocoagulation of ciliary body Anterior chamber shunt
Surgical management: blind eye
– Chemical ablation
- Gentamicine (Aminoglycoside) and dexamethasone
- 1/3 respond well
- 1/3 do not respond
- 1/3 respond too well – Phthisis bulbos
How/when would you use a laser to photo coagulate the ciliary body as a treatment for glaucoma?
– laser photocoagulation of ciliary body –> can try to preserve vision
• Diminish aqueous fluid production
• Temporary fix
• 50% visual at 1 year
Surgical management: visual eye – Anterior chamber shunt
- Aqueous humour exiting either through frontal sinus or through conjunctiva
- Longterm uveitis with fibrin blocking the tubing
Pilocarpine
a volatile alkaloid obtained from jaborandi leaves, used to contract the pupils and to relieve pressure in the eye in glaucoma patients. (agonist -> muscarinic acetylcholine receptor M3)
