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Exam 3
Glaucoma
37
Veterinary Medicine
Professional
11/18/2016

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Cards

Term
Definition: Glaucoma
Definition
-an inc in intraocular pressure incompatible with the health of the eye
Term
What produces the aqueous?
Definition
-epi of the ciliary processes
Term
Describe conventional aqueous flow.
Definition
-posterior chamber => pupil => anterior chamber => trabecular meshwork => scleral veins
Term
Describe unconventional aqueous flow.
Definition
-posterior chamber => pupil => anterior chamber => ciliary uscle => suprachoroidal space => scleral veins
Term
What is the physiology behind glaucoma?
Definition
-due to impaired aqueous OUTFLOW ONLY
Term
What structures in the eye does inc IOP damage due to glaucoma?
Definition
-optic nerve
-retina
-iris
-cornea
Term
What changes do the optic nerve and retina undergo due to inc IOP due to glaucoma?
Definition
-pressure damage to the ganglion cells and nerve fiber layer = degen of optic nerve
-Results in dark, cupped optic disc on fundus exam, vision loss, and afferent PLR deficit
Term
How does the iris change in response to inc IOP with glaucoma?
Definition
-pressure damage to the iris constrictor/sphincter muscles
-results: fixed dilated pupil and efferent PLR deficit
Term
How does hte cornea change in response to inc IOP with glaucoma?
Definition
-pressure exerted on the corneal endothelium impairs the ATPase pumps
-results in diffuse corneal edema
Term
What signs do we find in history of glaucoma?
Definition
-eye closed
-discharge
-bloodshot
-lethargy, anorexia
-cloudy (corneal edema)
-may appear more comfortabe with time
Term
What are the clinical signs of acute glaucoma?
Definition
-pain
-normal to hyperemic optic disc
-prominent scleral vessels
-corneal edema
-dilated pupil
Term
What are the clinical signs of chronic glaucoma?
Definition
-prominent scleral vessels
-corneal edema
-dilated pupil
-dark, cupped optic disc
-retinal atrophy
-bupthalmos
Term
What are the key triad clinical signs for glaucoma?
Definition
-episcleral vascular congestion
-corneal edema (diffuse)
-dilated pupil
Term
Describe how we use a Tonopen tonometer.
Definition
-requires topical anesthetic
-slightly higher learning curve
-operator touches cornea therefore can feel degree of IOP
Term
Describe how we use a TonoVet tonometer.
Definition
-no topical anesthetic required
-good for small eye (exotics practice)
Term
What drugs do we use to lower aqueous pdn to treat glacuoma?
Definition
-CArbonic angydrase inh: Dorzolamide, Brinzolamide
-Beta-adrenergic antagonists: Timilol
Term
What drugs do we use to inc aqueous outflow to treat glaucoma?
Definition
-prostaglandin analogs: Latanoprost
Term
When would we use a hyperosmotic (mannitol) to treat glaucoma?
Definition
-used only in acute glaucoma if latanoprost fails
Term
How do hyperosmotics work to treat glaucoma? How is it administered? When is it contraindicated?
Definition
-temporarily lowers IOP by dehydrating the vitrous
-admin IV over 15-20 mins
-withold water for 3-4 hr
-contraindicated with cardiac disease
Term
What are the surgical options to treat glaucoma?
Definition
-Laser cyclophotocoagulation: selectively destroys ciliary body tissue using laser energy
-Filtering implants: provides a new pathway for aqueous outflow
Term
What is primary glaucoma?
Definition
-no preceding intraocular disease
-structural abnormality of the trabecular meshwork that inhibits outflow
Term
In which breeds is primary glaucoma predisposed?
Definition
-Basset hound, spaniels, northern breeds, etc
Term
How do we diagnose primary glaucoma?
Definition
-breed
-history
-optho exam for primary or secondary
Term
Is primary glaucoma bilateral or unilateral?
Definition
-ALWAYS assume it is a bilateral disease
Term
How do we treat the eye affected by primary glaucoma?
Definition
-if vision permanently lost: enucleation, evisceration with intrascleral prosthesis, meds can be long term
Term
How do we treat the eye affected by primary glaucoma?
Definition
-MEdical: Latanoprost + Dorzolamide +/- Timilol w/ Mannitol IV if non-responsibe
-Surgical: laser cyclophotocoagulaiton and/or filtering implant
Term
How do we treat the eye unaffected by primary glaucoma?
Definition
-GOAL IS TO PROLONG THE ONSET OF GLAUCOMA
-start on 1 topical medication: brinzolamide, timilol, or latanoprost
-client education
-routine IOP checks q1-3 months
Term
What is the primary goal of maintaining vision due to primary glaucoma?
Definition
-higher IOP the lower the treatment success
-long term prognosis is always guarded
-ideal is to prolong the onset of glaucoma therefore always be proactive in the at-risk eye
Term
What are some of the difficulties encountered in treatment of primary glaucoma?
Definition
-first eye is not recognized/diagnosed in time
-medical therapy alone will not control IOP for life
-surgical procedures all have risks and may not cntrol IOP for life
Term
What are the clinical signs of secondary glaucoma?
Definition
-anterior lens luxation
-primary intraocular neoplasia
-uveitis
Term
How does uveitis cause ACUTE glaucoma?
Definition
-blood, fibrin, cells, etc by clogging the iridocorneal angle
Term
How does uveitis cause ACUTE or CHRONIC glaucoma?
Definition
posterior synechia blocking flow of aqueous through the pupil
Term
How does uveitis cause CHRONIC glaucoma?
Definition
-pre-iridal fibrovascular membrane covering the anterior surface of the iris and the iridocorneal angle
Term
What are the principles of treatment of secondary glaucoma?
Definition
-potential to regain vision => treat underlying disease
-permanently blind => evisceration or enucleation WITH HISTOPATHOLOGY
Term
How do we treat anterior lens luxation seen with secondary glaucoma?
Definition
-lens removal
Term
How do we treat primary intraocular neoplasia with secondary glaucoma?
Definition
-enucleation
Term
How do we treat uveitis with secondary glaucoma?
Definition
-suppress inflammaiton aggressively
-prevent posterior synechia: atropine is contraindicated
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