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Flashcards in Glaucoma Deck (22)
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1
Q

glaucoma

A

is defined as damage to the retinal ganglion cells and optic nerve due to increased IOP (intraocular pressure).

2
Q

Normal IOP in the dog

A

10-20 mmHg. Younger animals are usually on the higher end of normal and older animals are closer to the lower end.

3
Q

Normal IOP in the cat

A

Cats may be slightly higher, mostly due to sympathetic tone.

4
Q

Normal IOP in the horse

A

Horses range from about 12-26mmHg.

5
Q

Clincial signs of glaucoma (some or all):

A
  • Enlarged globe (buphthalmos)
  • Loss of vision
  • Episcleral injection (deep vessels)
  • Corneal edema
  • Dilated pupil, non responsive
  • Striae (linear breaks in the endothelium)
6
Q

Primary glaucoma:

A

Breed related, inherited. These animals will develop glaucoma
in both eyes over time. The genetics and pathophysiology are poorly understood.

7
Q

Secondary glaucoma

A
Lens luxation/subluxation
Uveitis
Cataract
Ocular neoplasia
Retinal detachment
Hyphema
8
Q

Acute glaucoma:

A

Treated as an emergency

Rapidly decrease IOP

9
Q

Dorzolamide/Timolol:

A

Dorzolamide is a topical CAI (carbonic anhydrase inhibitor); CA is required in the synthesis of aqueous, and when inhibited, results in decreased production of aqueous.
Timolol is a beta blocker and decreased aqueous production by vasoconstriction.
This is not the most rapid drug to use to decrease the pressure, but it can be used in the

10
Q

Latanoprost 0.005%

A

Latanoprost is a synthetic prostaglandin. Prostaglandins are mediators of inflammation and the mechanism of the drug is similar to naturally occurring uveitis, which causes a decrease in aqueous production and increases aqueous outflow via alternate pathway (uveoscleral).

11
Q

Caveat of using latanoprost

A

Latanoprost causes the pupil to be extremely miotic (similar to uveitis) which impairs the ability to visualize the fundus & lens when referred.

12
Q

contraindication of latanoprost

A

DO NOT USE Latanoprost with an ANTERIOR LENS LUXATION (traps vitreous in pupil and lens anteriorly) or GLAUCOMA SECONDARY TO UVEITIS (prostaglandin-worsen uveitis, increases IOP).
This should be only be used under the supervision of an ophthalmologist.

13
Q

IV Mannitol:

A

If IOP > 40mmHg, and the pressure does not respond to Dorzolamide/Timolol or Latanoprost, mannitol can be given to “dehydrate” vitreous.Not used for glaucoma secondary to uveitis as the choroidal vessels are more permeable allowing mannitol molecules to cross into the vitreous, bringing water with it resulting in increased IOP.

14
Q

If uveitis is present with glaucoma

A

AVOID latanoprost and mannitol.
AVOID atropine as it will increase IOP further.
Give oral NSAID
Apply topical Prednisolone acetate if NO corneal ulceration or Diclofenac if corneal ulcer is present.

15
Q

ultimate treatment for glaucoma

A

enucleation

16
Q

Clinical signs of chronic glaucoma

A

-Buphthalmia – enlarged globe, outer fibrous tunic stretches in response to high pressure
-Corneal edema-variable in cats & horses, seen in most dogs
-Dilated pupil – absent PLR
-Absent menace
-Pain ** do not overlook this because the dog is blind –it may not be obvious until the
eye has been removed. Some animals are just less active than usual.
-Episcleral injection – large straight vessels congested over sclera
-Corneal striae – “stretch marks” in stroma from breaks in endothelium-white streaks
-Retinal degeneration (hyperreflectivity, vascular attenuation)
-Cupped optic disc – loss of myelin and nerve fibers, depressed nerve head

17
Q

surgical options for glaucoma

A

Enucleation
Evisceration with prosthesis NOT ON CATS
pharmacologic ablation (not for cats, not effective in general)

18
Q

feline glaucoma - what breed

A

siamese

19
Q

Secondary glaucoma in cats

A

occurs with uveitis, intraocular neoplasia, hemorrhage and lens luxation.

20
Q

Aqueous misdirection syndrome

A

This is unique to the cat. Aqueous is directed into the vitreous through a rent in the vitreal face, causing the lens/iris to be anteriorly displaced leaving a very shallow anterior chamber –the differential for aqueous misdirection syndrome is lens luxation. Treatment is challenging. There may be response to Dorzolamide/Timolol, but lens removal may be necessary to control pressure and save vision.

21
Q

Treatment for feline glaucoma:

A

One drop every 12 hours is recommended. Timolol is a beta blocker and has systemic effects when applied topically; use caution if cardiac or respiratory disease exists.
Carefully examine the patient for evidence of uveitis or lens instability as these are often the underlying cause of glaucoma in cats.

22
Q

What drugs are not appropriate for glaucoma

A

Steroids are NOT appropriate treatment for glaucoma.

Dilation of the pupil may cause pressure spikes in animals with lens instability or patients predisposed to glaucoma.