Unit 2 - Glaucoma Flashcards
What are ‘the glaucomas?’
a group of diseases characterized by increased intraocular pressure and progressive degeneration of the optic nerve and retina
Why do we care about the glaucomas?
Pain and vision loss
What is the pertinent anatomy to glaucoma?
Ciliary body
Posterior and anterior chambers
Iridocorneal angle
Pectinate ligaments
Ciliary cleft
What is the normal intraocular pressure of dogs and cats?
10-20 mmHg
What is the normal intraocular pressure in horses?
15-30 mmHg
What produces aqueous humor?
Ciliary body epithelium
What enzyme is in charge of active secretion of aqueous humor from the ciliary body epithelium?
Carbonic anhydrase
What is in charge of the outflow of aqueous humor?
Iridocorneal angle - trabecular neshwork (conventional) and uveoscleral (non-conventional)
Normal intraocular pressure relies on what?
A balance between production and outflow of aqueous humor
Glaucoma is always due to what (physiologic level)?
Impaired outflow
The clinical signs of glaucoma vary depending on what?
Severity, duration, and cause
What clinical signs are consistent with glaucoma (not chronic)?
Decreased to absent vision
Migraine pain
Injected episcleral vessels
Dilated pupil
Diffuse corneal edema
Optic nerve cupping
What clinical signs are consistent with chronic glaucoma?
Buphthalmos, Haab’s striae, lens subluxation, and retinal degeneration
What is the preferred tool for diagnosing glaucoma?
Tonovet
Other options: Digital (fingers), Schiotz or cotton swab (indentation), and Tonopen
Tonovet uses ______ tonometry and it (does/does not) require topical anesthetic to use. Tonopen uses _____ tonometry and it (does/does not) require topical anesthetic to use.
Rebound
Does not
Applanation
Does
You have glaucoma if what two things are occuring?
There is elevated IOP and consistent clinical signs
Classify primary glaucoma.
Occurs without antecedent ocular disease
Breed-related
Bilateral
Eventually blinding
Treat early to prolong vision and comfort
Classify secondary glaucoma.
Sequelae from other intraocular disease
Most common in cats and horses
Unilateral or bilateral
Treat underlying cause for better prognosis
What is the most common form of glaucoma in dogs?
Primary
What is goniodysgenesis?
Iridocorneal angle malformation
What is the typical signalment for primary glaucoma?
Females are at a greater risk
Average age of onset 6-8 years
Secondary glaucoma is a sequelae of what diseases?
Uveitis, lens luxation, intraocular neoplasia, and others (hyphema, retinal detachment, intumescent cataract)
How does uveitis cause secondary glaucoma?
Inflammatory cells clog the drain
Iris bombe is the synechiae
What is used to differentiate between primary and secondary glaucoma?
Signalment
Ophthalmic examination
Gonioscopy
Histopathology
What is gonioscopy?
The visualization of the iridocorneal angle using a special lens
What are the general principles of glaucoma management?
Must recognize the clincal signs
Determine if primary or secondary
Prognosticate vision
Lower IOP as quickly as possible
What two questions should you ask yourself in regards to treatment of glaucoma?
Is the eye visual or not?
Is the glaucoma primary or secondary
‘Is the eye visual or not?’ How would you treat it if it was visual? Not visual?
Visual - medical +/- surgical therapies
Non-visual - salvage procedures for end-stage globe
‘Is the glaucoma primary or secondary?’ How would you treat if primary? Secondary?
Primary - treat affected eye but remember to start prophylactic therapy for contralateral eye
Secondary - treat glaucoma but also underlying cause
What is the goal of prophylactic glaucoma therapy of the contralateral eye?
Delay the onset of glaucoma by several months
What are the options for prophylactive glaucoma treatment?
Demecarium bromide - 0.125%
Prednisolone acetate 1%
What are the recommended general medications for glaucoma therapy?
Carbonic anhydrase inhibitors
Prostaglandin analogs
Beta blockers
Parasympathomimetics
Hyperosmotic agents
What are the recommended carbonic anhydrase inhibitors for the treatment of glaucoma?
Dorzolamide or brinzolamide BID-QID
What are the recommended prostaglandin analogs for the treatment of glaucoma?
Latanoprost or travoprost SID-TID
What are the recommended beta blockers for the treatment of glaucoma?
Timolol BID
What are the recommended parasympathomimetics for the treatment of glaucoma?
Demecarium bromide
What are the recommended hyperosmotic agents (emergency) for the treatment of glaucoma?
Mannitol IV or glycerin PO
What drugs should not be used for the treatment of glaucoma?
Never use dilating agents (atropine or tropicamide)
Timolol - caution in cats and small dogs
No miotic agents (latanoprost, demecarium bromide) if anterior lens luxation
If uveitis - add latanoprost
What is the recommended emergency treatment for acute glaucoma?
Hyperosmotic agents (mannitol or glycerin) - draws fluid from vitreous
Dorzolamide +/- timolol topical
Aqueocentesis if medications are ineffective (27 or 30 gauge)
When should a patient be rechecked after glaucoma diagnosis?
1 day, then 1 week, then 1 month
T/F: Primary glaucoma is a good long-term prognosis
False - poor
What are the surgery options for visual glaucoma patients?
Diode laser treatment of ciliary body
Gonioimplant to increase AH outflow
Experimental surgeries under investigation
What are the glaucoma surgery options for end-stage for irreversibly blind, painful eyes?
Enucleation
Evisceration with prosthesis
Chemical ablation
T/F: Chemical ablation is just for end-stage glaucoma in dogs
True - bad for cats
What are important things to let your clients know when their pet has been diagnosed with glaucoma?
Poor prognosis
Progression is variable, but slower with therapy
If primary - the contralateral eye will become affected but slower and less severe with prophylactic therapy
Usually results in blindness
Painful IOP not controlled
comfort is a priority
