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Glaucoma 389

○ Topical carbonic anhydrase inhibitors ○ Enucleation or evisceration and implant • Clinical management of glaucoma is often
(CAIs) (topical 2% dorzolamide or 1% surgeries should be followed with histo- difficult, and referral of these cases to a
VetBooks.ir ○ Topical dorzolamide/timolol combination help determine cause of glaucoma (i.e., • Medical therapy of glaucoma is expensive Diseases and Disorders
veterinary ophthalmologist is advised.
brinzolamide q 8h, decreases pressure
pathologic exam of the removed tissue to
about 5-7 mm Hg)
and is often required long term.
primary vs. secondary) and prognosis for
(q 12h) can be administered rather than
the individual products. fellow eye. • Buphthalmos indicates chronic glaucoma,
whereas acute glaucoma, with its potentially
• Mannitol 1-2 g/kg IV over 20 minutes Drug Interactions better prognosis for vision, manifests with
(usually greatly decreases pressure) to • Topical beta-adrenergic blockers may lower episcleral injection and almost never with
rapidly lower IOP (first effects in 1-2 heart rate and blood pressure and may cause buphthalmos.
hours; maximum effect in 4-6 hours; dura- bronchoconstriction in small-breed dogs and • Treatment (e.g., evisceration and implant,
tion ≈8-10 hours) when there is a chance in cats. enucleation) is generally indicated for per-
for return of vision (e.g., acute primary • Systemic CAIs in dogs and cats are rarely used manently blind, persistently glaucomatous
glaucoma) since the advent of topical CAIs because they eyes to remove the source of chronic intense
• Topical prostaglandins (PGF analogs, 0.005% may cause metabolic acidosis and electrolyte pain.
latanoprost, 0.03% bimatoprost, or 0.004% imbalances, as evidenced by depression • Digital pressure (pressing on the eyes through
travoprost q 8-24h), usually greatly decrease (perhaps related to hypokalemia), and in closed eyelids) cannot be used to accurately
pressure: used for primary glaucoma in dogs; dogs, vomiting and diarrhea that require assess IOP.
not as effective in the feline glaucomas) may drug cessation. Topical CAI preparations
be used in the emergent case to promptly are rarely associated with these side effects. Prevention
lower IOP; however, they should not be used • Topical prostaglandins often cause con- The benefits of periodic tonometry in breeds
in cases of lens luxation or instability or be junctival hyperemia within minutes after and/or eyes at risk are unknown but should be
used with caution when there is significant instillation that gradually declines over an considered. Anterior uveitis that is unrecognized
uveitis. hour or so and miosis that persists with the or inadequately treated and controlled predis-
• Topical q 6h corticosteroids (prednisolone IOP reduction. poses an eye to secondary glaucoma. Cataractous
1% or dexamethasone 0.1%) are indicated • Mannitol, an osmotic diuretic, should be eyes should be examined regularly for evidence
if anterior uveitis is also present with no avoided in patients with heart disease (risk of of lens-induced uveitis, and treatment should
corneal ulceration. fluid overload/iatrogenic pulmonary edema). be initiated when signs appear to prevent or
delay glaucoma.
Chronic Treatment Possible Complications
Medical: With poor or inadequate control of IOP, any Technician Tips
• Topical carbonic anhydrase inhibitors (2% or all of the following may occur: • Veterinary nurses and technicians should
dorzolamide or 1% brinzolamide q 8h) • Buphthalmos (p. 705) causing increased encourage clients to bring their pets in for
• Topical beta-adrenergic antagonists or block- corneal exposure ± recurrent corneal evaluation promptly to rule out glaucoma if
ers (0.5% timolol or 0.5% betaxolol, usually ulceration/corneal vascularization/corneal they complain of a bloodshot eye or acute
q 8-12h) pigmentation visual disturbance.
• Topical prostaglandins (PGF analogs, 0.005% • Lens luxation/subluxation • Restraint for animals undergoing tonometry
latanoprost, 0.03% bimatoprost, or 0.004% • Optic nerve and retinal degeneration is important. Care should be taken to avoid
travoprost q 12-24h): used for primary • Ocular, head pain placing any pressure on the jugular veins or
glaucoma in dogs; not as effective in feline • Blindness eyelids because excessive pressure in these
glaucomas areas may result in falsely elevated IOP
• ± Topical and/or systemic corticosteroids Recommended Monitoring measurements. Excessive struggling should
(prednisolone) (when anterior uveitis also • Regular exams with tonometry (e.g., monthly be avoided as well because this may alter
present; taper to lowest effective dose) after IOP control initially achieved) are nec- IOP readings.
• In all of the breed-related primary glaucomas, essary to monitor IOP (should be maintained
the disease continues to progress (even at < 15 mm Hg) and maintain vision for as Client Education
though IOP may be controlled), and often, long as possible. • Glaucoma is a chronic disease that requires
combinations of several topical IOP-lowering • As the glaucoma progresses, increased regular and diligent therapy. Missed medica-
drugs or surgery (see below) are eventually frequency and/or additional topical drugs tion results in inadequate control of IOP,
necessary. to lower IOP are usually necessary. loss of sight, and pain.
Surgical: • Primary glaucoma occurs in more than 20
• Anterior chamber shunts and laser cyclo- PROGNOSIS & OUTCOME dog breeds.
photocoagulation are procedures offered by • Dogs with cataracts that are not surgical
most veterinary ophthalmologists to prolong • Prognosis is usually poor for the first eye candidates require periodic eye exams and
vision and prevent ocular pain. Laser cyclo- presented with primary glaucoma in dogs tonometry indefinitely because they are at
photocoagulation may be performed with a because the disease is often advanced and increased risk for developing glaucoma.
transscleral approach or with the assistance refractory to medical therapy.
of a microendoscope. • Prognosis for the fellow eye is better, and SUGGESTED READING
• Removal of the lens (referable procedure; prophylactic therapy with a beta-adrenergic Plummer CE, et al: The canine glaucomas. In Gelatt
glaucoma secondary to lens luxation) should blocker or prostaglandin can significantly delay KN, editor: Veterinary ophthalmology, ed 5, Ames,
be performed as soon as possible in cases of the onset of glaucoma for up to 30 months. IA, 2013, Wiley-Blackwell, pp 900-1142.
anterior lens displacement/luxation.
• End-stage blind and buphthalmic glauco- PEARLS & CONSIDERATIONS AUTHOR: Caryn E. Plummer, DVM, DACVO
EDITOR: Diane V. H. Hendrix, DVM, DACVO
matous globes may be treated by
○ Enucleation Comments
○ Evisceration and intrascleral prosthesis • Patients with dilated pupils, corneal edema,
○ Intravitreal gentamicin or cidofovir injec- and conjunctival hyperemia require tonom-
tion (dogs) etry to estimate IOP.

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