Page 1329 - Clinical Small Animal Internal Medicine

138 Tumors of the Eye and Ocular Adnexa 1267

tumors that have been reported is unproven, it is difficult distant metastasis. In cats and dogs, 90% or more of
VetBooks.ir to automatically advise enucleation of normotensive, orbital tumors are malignant, and regional infiltration
(including into the CNS) or distant metastasis is com-
noninflamed, visual eyes. Therefore, canine primary
intraocular tumors are generally photographed and care-
described in cats and dogs. Tumors involving the optic
fully followed for progression. Enucleation is advised if mon. Numerous types of orbital tumors have been
malignancy is a concern or if intractable uveitis, chronic nerve are rare, although secondary invasion of the nerve
hyphema, or secondary glaucoma is present. Isolated may occur in feline posttraumatic sarcomas, feline SCC,
primary masses involving only the iris or a portion of the canine choroidal melanomas, and canine meningiomas.
ciliary body may be amenable to local resection by sector
iridectomy/cyclectomy with preservation of the globe, Primary Orbital Tumors
but this procedure requires an accomplished ophthalmic
surgeon and often has unsatisfactory long‐term results. Sarcomas
Transscleral and transcorneal Nd:YAG or diode laser Mesenchymal tumors are among the most common
therapy may induce remission in small to moderate‐sized canine primary orbital tumors. These include osteosar-
primary intraocular tumors while also preserving vision. comas, fibrosarcomas, reticulum cell sarcomas, and
neurofibrosarcomas. Orbital tumors should be histologi-
cally graded for a more accurate prognosis but most sar-
Prognosis
comas are locally invasive and carry a poor prognosis.
The prognosis for histologically benign intraocular
tumors is excellent. Enucleation is curative but blinding. Canine Lobular Orbital Adenoma
Attempts at local excision or laser photoablation may Lobular adenomas, perhaps originating from the lacri-
only be palliative, especially if the ciliary body or trabec- mal gland, may involve the anterior orbit in dogs. They
ular meshwork is involved. typically present as soft, smooth conjunctival swellings,
or space‐occupying orbital lesions that can cause either
enophthalmia or exophthalmia. Lobular orbital adeno-
Secondary Uveal Neoplasms
mas are composed of multiple friable lobules, making
Because the uveal tract is highly vascular, numerous complete surgical excision challenging. Although benign,
malignant tumors have been reported to metastasize recurrence is common, often 1–2 years after excision.
to the eye. Lymphoma is the most common secondary
intraocular tumor in the dog and cat, with ocular lesions Meningioma
affecting approximately one‐third of dogs with the disease. Canine orbital meningiomas are uncommon tumors
Common clinical signs include a severe uveitis, in which which tend to grow slowly and rarely metastasize.
the amount of anterior chamber cell/flare is disproportion- Invasion of surrounding tissues, including bone and the
ally severe compared to the degree of conjunctival CNS, is possible.
hyperemia and pupillary miosis. Other clinical signs include
secondary glaucoma, retinal hemorrhage and detach- Glioma
ment, hyphema, conjunctivitis, and keratitis characterized Gliomas are rare primary optic nerve tumors in dogs.
by corneal infiltrates, edema, vascularization, and intras- The metastatic potential of gliomas appears to be low,
tromal hemorrhage. Exophthalmia from orbital invasion but invasion into the retina or the ventral aspect of the
and vision loss due to optic nerve or central nervous brain is possible.
system (CNS) disease may also occur. Dogs with intraocular
lymphoma survive only 60–70% as long as dogs without History and Clinical Signs
ocular involvement when treated with cyclophosphamide,
vincristine, and prednisolone (COP), or with doxorubicin. Orbital neoplasia is typified by slowly progressive
Ocular signs may be palliated by topical or systemic corti- exophthalmia, absent to minimal pain on opening the
costeroid therapy, but the most effective therapy is systemic mouth, difficulty in retropulsing the eye, and deviation
chemotherapy directed at the cancer itself. Enucleation may of the globe. Nasal or sinus tumors that suddenly erode
be necessary for pain relief in some patients. into the orbit occasionally result in acute exophthalmia
and substantial orbital pain. If the mass is anterior to the
equator of the globe, enophthalmia may occur. Chronic
Tumors of the Orbit and Optic Nerve epiphora secondary to obstruction of the nasolacrimal
duct, exposure keratoconjunctivitis, palpable orbital
Orbital neoplasia may be primary, secondary to exten- masses, or unexplained orbital pain also suggest orbital
sion of adjacent tumors into the orbit, or the result of neoplasia. Measurement of corneal diameters and