Glaucoma Flashcards by Emily Wirth

What is the aqueous humor flow?

Ciliary body > posterior chamber > pupil > anterior chamber > iridocorneal angle > venous drainage

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What is glaucoma almost always due to?

Impaired outflow

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Where do the majority of species outflow aqueous humor?

Iridocorneal angle

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What are the acute clinical signs of glaucoma?

Episcleral injection
Blepharospasm
Corneal edema
Mydriasis
Impaired vision

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What are the chronic clinical signs of glaucoma?

Optic disc cupping
Retinal degeneration
Irreversible blindness
Buphthalmos (larger stretched out globe - haab’s stria (stretch marks))
Phthisis bulbi (shrinking of the eye - super end stage)
Lens subluxation

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What does a buphthalmic globe indicate? Execept in?

Blindness
Except in puppies and shar peis

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What is the IOP difference between buphthalmia and exophthalmia?

Often markedly elevated with buphthalmia
Normal or mildly elevated with exophthalmia

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What is the corneal diameter difference between buphthalmia and exophthalmia?

Larger with buphthalmia
Normal with exophthalmia

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What is the lens luxation difference between buphthalmia and exophthalmia?

Secondary subluxation with buphthalmia
Normal with exophthalmia

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What is the vision difference between buphthalmia and exophthalmia?

Blind with buphthalmia
Usually visual with exophthalmia

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What is a normal IOP?

12-24 mmHg

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When should you check the IOP?

With every red eye (episcleral injection) with an intact cornea

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What is the most accurate IOP?

The lowest

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What is a main issue with tonopens?

Reduced accuracy at higher IOP especially with cats
Significantly underestimates IOP

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How does applanation tonometry work?

Correlates force to flatten cornea with IOP
Local anesthetic is recommended

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How does rebound tonometry work?

Correlates speed of bounce off cornea to IOP
No topical anesthetic is needed

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How does rebound tonometry work?

Correlates speed of bounce off cornea to IOP
No topical anesthetic is needed
More accurate

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What is the most common primary glaucoma in dogs?

Primary angle closure glaucoma

What breeds are predisposed to primary angle closure glaucoma?

Cocker spaniels and basset hounds

What type of glaucoma are beagles predisposed to?

Primary open angle glaucoma

What is secondary glaucoma associated with?

Other ocular or systemic abnormalities

What are the three most common causes of secondary glaucoma?

Uveitis - most common
Neoplasia
Lens luxation

What is the pathogenesis of primary angle closure glaucoma?

Development of iridocorneal angle arrested
Aqueous production does not = aqueous outflow
Aqueous outflow decreases so IOP increases
Diagnosis of exclusion

What is gonioscopy used for?

Examine the iridocorneal angle
Referral procedure
Subjective

What is the common signalment of primary angle closure glaucoma?

Female Middle-aged to older dog Cocker spaniel or basset hound Glaucoma develops in other eye ~ 8 months later

What should you prepare patients for with a glaucoma patient?

A blind dog We almost always eventually fail to preserve vision and are often considering comfort

What is the most effective canine therapy for primary glaucoma?

Latanoprost 0.0005% Topical prostaglandin derivative (mimics uveitis) Increases uveoscleral outflow Potent mitotic

When are prostaglandin derivatives contraindicated?

Secondary glaucoma due to severe uveitis Anterior lens luxation Not effective in most forms of feline glaucoma

What should you use for secondary glaucoma in dogs and glaucoma in cats and horses?

Dorzolamide 2% / Timolol Decreases aqueous production Does not affect pupil size Carbonic anhydrase inhibitor Given between drops of Latanoprost

What can be used for inflammation control topically?

Neo/poly/dex 0.1% Prednisolone acetate 1%

What can be used if topical medication is ineffective?

IV mannitol 20% Hyperosmotic Dehydrates vitreous

What are the contraindications when using Mannitol?

Heart disease DM Renal failure Uveitis

What is the prognosis for medical management of glaucoma?

Medical therapy will often fail within 6 months Glaucoma is progressive and does not go away

What surgical therapy can be done to increase outflow?

Gonioimplants Tube inside anterior chamber Gives you about 6 months of control of IOP before failure due to fibrosis

What surgical therapy can be done to decrease production of aqueous humor?

Destruction of the ciliary body Cyclophotocoagulation - diode laser Laser is dependent on pigment so it is not consistent

What are the complications of using a diode laser?

Postoperative pressure spike Cataract formation Inflammation

What should be done for the other healthy eye?

Prophylactic therapy Dorzolamide/Timolol Demarcarium bromide Latanoprost Recheck every 1-3 months

What are the three treatment options for end stage glaucoma?

Enucleation Intrascleral prosthesis (remove inner contents of globe and place silicone ball) Chemical ciliary body ablation (intravitreal gentamicin or cidofovir)

What are the contraindications for intrascleral prosthesis and chemical ciliary body ablation?

Corneal disease Uveitis Tumor

What is feline glaucoma usually due to?

Uveitis

What is the most common complaint of feline glaucoma?

Mydriasis

What procedure is contraindicated in cats?

Chemical ciliary body ablation Can lead to aggressive tumor formation

What is the only salvage procedure available for cats?

Enucleation Do not put a prothesis - they like to reject them