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Categories

Venous obstruction

In patients with thyroid eye disease, contracture of extraocular muscles and infiltration of the plasma cells and lymphocytes into the orbit may lead to an elevated venous pressure.

It must be kept in mind that thyroid dysfunction may lead to an elevated venous pressure as well as abnormal scleral rigidity. Retro-orbital tumors, cavernous sinus thrombosis, and lesions that obstruct venous return from the head also may cause venous obstruction and elevated venous pressure.

Carotid cavernous fistula

The typical carotid cavernous fistula occurs as a result of severe head injury; a large fistula is created between the internal carotid artery and the surrounding cavernous sinus venous plexus. The condition is characterized by pulsating exophthalmos, a bruit over the globe, conjunctival chemosis, engorgement of episcleral venous veins, and restriction of motility with evidence of ocular ischemia. The shunting of the internal carotid cavernous fistula causes high flow and high pressure. A more recently appreciated form of carotid cavernous fistula is the ‘low-flow’ shunt. These small fistulas may occur without a history of trauma. In these cases, the shunt is fed by a meningeal branch of the intracavernous internal carotid artery or external carotid artery that empties directly into the cavernous sinus or adjacent dural vein that connects with the cavernous sinus. Whether the patient has a highor low-flow shunt, elevated pressure occurs. Venous backpressure may increase the episcleral venous pressure, which is the most common cause of intraocular pressure rise with the fistula. Angle-closure glaucoma has also been reported in association with carotid cavernous fistula.

Sturge–Weber syndrome

In this syndrome, a hamartoma arises from the vascular tissue and produces a characteristic port-wine stain hemangioma of the skin in a trigeminal distribution. Several mechanisms of glaucoma are possible in these patients, but at least some patients seem to have an open anterior chamber angle with low arteriovenous pressure, usually associated with stooping over or a Valsalva maneuver.

Idiopathic

These patients are elderly with no family history of the condition. The cause of the elevated venous pressure is unknown, and the associated glaucoma may be severe.

TREATMENT

●The treatment for glaucoma associated with elevated venous pressure is the same as that for other forms of glaucoma.

●In cases in which a carotid cavernous fistula or low-flow shunt is present, pharmacologic glaucoma control should be considered before surgical intervention is contemplated when the glaucoma is the only condition prompting consideration of surgery.

●In some instances, angiography alone is sufficient to prompt low-flow fistulas to close spontaneously.

Surgical

●If surgical intervention is necessary, a filtering procedure should be used.

●There is no doubt that these patients are at substantially increased risk for uveal effusion and expulsive hemorrhage. This should be included in the consent process. It has been recommended that drainage of the suprachoroid be routinely performed at the time of surgery.

●Prophylactic sclerotomy should routinely be performed at the same time as the filtering procedure.

PRECAUTIONS

Repair of carotid cavernous fistulas may be hazardous and is a controversial area in neurosurgery. If glaucoma is the sole cause for intervention, one should be certain that it is significant and difficult to treat, and that visual field progression is present. Elevated episcleral venous pressure as a cause of glaucoma is often overlooked. Because these patients do have increased complications at the time of filtering surgery, careful consideration of episcleral and conjunctival vessels before filtration is always indicated.

The consenting process should inform the patient that there is increased risk of choroidal hemorrhage when trabeculectomy is performed. Alternative, non-penetration surgeries for glaucoma may be useful in these cases.

REFERENCES

Bellows AR, Chylach LT, Jr, Epstein DL, et al: Choroidal effusion during glaucoma surgery in patients with prominent episcleral vessels. Arch Ophthalmol 97:493–497, 1979.

Harris GJ, Rice PR: Angle closure and carotid cavernous fistula in a series of 17 cases. Am J Ophthalmol 48:585–597, 1959.

Palestine AG, Young BR, Pipegras DG: Visual prognosis and carotid cavernous fistula. Arch Ophthalmol 99:1600–1603, 1981.

Podos SM, Minas TF, MacRif J: A new instrument to measure episcleral venous pressure: Comparison of normal eyes and eyes with primary open angle glaucoma. Arch Ophthalmol 80:209–213, 1968.

Radius RL, Maumenee AE: Dilated episcleral venous vessels and openangle glaucoma. Am J Ophthalmol 86:31–35, 1978.

263 GLAUCOMA ASSOCIATED WITH

INTRAOCULAR TUMORS 365.64

(Tumor Related Glaucoma,

Melanomalytic Glaucoma,

Melanocytomalytic Glaucoma,

Neovascular Glaucoma, Angle Closure

Glaucoma)

Carol L. Shields, MD

Philadelphia, Pennsylvania

Jerry A. Shields, MD

Philadelphia, Pennsylvania

ETIOLOGY/INCIDENCE

A number of intraocular tumors can produce ipsilateral elevation of the intraocular pressure. In such instances, there may be a delay in clinical recognition of the underlying neoplasm while the patient is treated for the secondary glaucoma. In cases

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of malignant tumors, this delay in diagnosis can have serious consequences.

In contrast to the primary glaucomas, which are generally bilateral, tumor-induced secondary glaucomas are almost always unilateral. The mechanism of the secondary glaucomas varies with the location, size, and type of tumor. Malignant tumors in the iris and ciliary body are more likely to obstruct aqueous outflow by directly infiltrating the trabecular meshwork. More posteriorly located intraocular neoplasms can produce anterior displacement of the lens-iris diaphragm causing angle closure, they can induce iris and angle neovascularization causing neovascular glaucoma, or they can liberate tumor cells in the anterior chamber angle, blocking aqueous outflow.

Primary tumors of the uvea

Nevus

Uveal nevi are benign lesions which rarely produce secondary glaucoma. Occasionally, however, localized or diffuse uveal nevi can lead to secondary glaucoma. This most often occurs with a melanocytoma or with a diffuse nevus of the iris. Melanocytoma is a specific variant of nevus which usually occurs in the optic disc, but which can arise anywhere in the uveal tract. Those located in the optic disc or choroid rarely produce secondary glaucoma whereas those which occur in the ciliary body or iris are more likely to produce secondary glaucoma by anterior chamber angle infiltration with discohesive tumor or necrotic cells, often engulfed by macrophages (melanocytomalytic glaucoma).

Melanoma

Of all patients with uveal melanoma, secondary glaucoma is found in approximately 3%.

Iris melanoma is associated with secondary glaucoma in 7 % of cases and the most common mechanism of glaucoma is direct invasion of the trabecular meshwork by tumor tissue. Occasionally spontaneous hyphema is the cause of increased intraocular pressure. The diffuse iris melanoma produces a classic syndrome of acquired hyperchromic heterochromia and ipsilateral glaucoma. Iris melanoma invasion into the angle and secondary glaucoma are the two most important risk factors for metastases.

In contrast to iris melanoma, ciliary body melanoma tends to attain a fairly large size prior to diagnosis. Ciliary body melanomas cause secondary glaucoma in 17% of cases and the mechanisms include anterior displacement of the iris with secondary angle closure or direct invasion of the trabecular meshwork. Less commonly, hyphema, necrosis, or iris neovascularization, are found as the cause of secondary glaucoma.

Published studies show that only 2% of patients with choroidal melanoma have secondary glaucoma. When secondary glaucoma occurs due to a choroidal melanoma it is from iris and angle neovascularization (56%) or anterior displacement of the lens-iris diaphragm and secondary angle closure (44%). Large necrotic choroidal melanomas can occasionally produce intraocular inflammation or hemorrhage, which can further contribute to secondary glaucoma.

Others

Other rare uveal tumors such as neurilemomas, leiomyomas, neurofibromas can produce secondary glaucoma by the same mechanisms.

Metastatic tumors to the uvea

Malignant tumors from distant primary sites metastasize via hematogenous routes to the uveal tract and rarely to the retina or optic nerve. Choroidal metastases only produce secondary glaucoma when they attain a large size, whereas iris and ciliary body metastases frequently produce secondary glaucoma because of their tendency to be friable and also involve the angle structures. In our series of patients with uveal metastases, secondary glaucoma was found in 64% of iris metastasis, 67% of ciliary body metastasis, and 2% of choroidal metastasis.

Iris and ciliary body metastases usually produce secondary glaucoma by seeding into the anterior chamber angle and trabecular meshwork, mechanically blocking aqueous outflow. In some cases, a solid growth of tumor cells can assume a ring type infiltration of the trabecular meshwork resulting in intractable glaucoma.

Metastatic tumors to the choroid appear as single or multiple elevated or diffuse lesions often associated with a secondary nonrhegmatogenous retinal detachment. The most common mechanism of glaucoma with choroidal metastases is angle closure due to anterior displacement of the lens-iris diaphragm secondary to total retinal detachment. Neovascular glaucoma can occur in advanced cases with total retinal detachment.

Primary tumors of the retina

Tumors of the sensory retina include retinoblastoma, vascular tumors, glial tumors, and others. Retinoblastoma, the most important retinal tumor, frequently produces secondary glaucoma. In rare instances, advanced retinal capillary hemangiomas can produce secondary glaucoma in association with a total retinal detachment.

In our series of 248 patients with retinoblastoma, 17% of 303 affected eyes had secondary glaucoma. The secondary glaucoma was due to iris neovascularization in 72%, angle closure secondary to anterior displacement of the lens-iris diaphragm in 26%, and tumor seeding into the anterior chamber in 2%. In cases with iris neovascularization, secondary hyphema sometimes contributed to the mechanism of glaucoma. The presence of iris neovascularization and secondary glaucoma in an eye with retinoblastoma is a statistical risk for optic nerve invasion, choroidal invasion, and eventual metastases.

Tumors of the nonpigmented and pigmented epithelium

Tumors of the nonpigmented epithelium of the ciliary body include medulloepithelioma, adenoma, and adenocarcinoma. The medulloepithelioma (previously called diktyoma) is an embryonic ciliary body tumor which becomes clinically apparent in the first few years of life. In two large series of medulloepithelioma, secondary glaucoma occurred in approximately 50% of cases. In these cases, glaucoma occurred secondary to iris neovascularization or from direct invasion of the anterior chamber angle structures by the tumor. In some instances, hyphema or cysts in the anterior chamber also contributed to obstruction of aqueous outflow.

Acquired tumors of the nonpigmented ciliary epithelium are rare, slow growing benign or lowly malignant lesions and they rarely produce secondary glaucoma. Primary tumors of the pigmented epithelium (adenoma and adenocarcinoma) of the iris, ciliary body, and retina are rare. The mechanisms of glaucoma are the same as those of malignant melanoma.

Lymphoid tumors and leukemias

Lymphoid tumors and leukemias can produce a similar infiltration of the uveal tract and retina. The most important lymphoid tumors of the intraocular structures include benign reactive lymphoid hyperplasia (BRLH) of the uvea and malignant lymphoma, particularly large cell lymphoma (histiocytic lymphoma, reticulum cell sarcoma). Secondary glaucoma most often occurs from direct infiltration of the anterior chamber angle and thickening of the iris and ciliary body by tumor cells. This results in blockage of aqueous outflow and secondary elevation of intraocular pressure.

Systemic hamartomatoses (phakomatoses)

The classic phakomatoses include encephalofacial hemangiomatosis (Sturge–Weber syndrome) neurofibromatosis (von Recklinghausen’s syndrome), retinocerebellar capillary hemangiomatosis (von Hippel–Lindau syndrome) and tuberous sclerosis (Bourneville’s syndrome). The two which are more likely to be associated with either infantile or juvenile glaucoma include encephalofacial hemangiomatosis and neurofibromatosis.

COURSE/PROGNOSIS

The course and prognosis of the patient depends on the primary tumor type, location, size, and other features. Glaucoma associated with iris melanoma is associated with a worse ocular and systemic prognosis compared to iris melanoma without glaucoma. Glaucoma associated with retinoblastoma is associated with a greater risk for optic nerve and choroidal invasion of the tumor, imparting a greater risk for metastatic disease.

DIAGNOSIS/LABORATORY FINDINGS

Clinical

●Examination may show an intraocular mass.

●Slit lamp biomicroscopy may reveal neovascularization of the iris.

●Gonioscopy may reveal angle invasion by tumor or angle vessels.

●Transillumination may show a ciliary body or choroidal shadow.

Ocular tests

●Ultrasonography may demonstrate an intraocular mass.

●Ultrasound biomicroscopy can show anterior chamber angle invasion or ciliary body tumor.

●Fluorescein angiography or indocyanine green angiography may demonstrate an intraocular mass or show iris neovascularization.

●Magnetic resonance imaging or computed tomography may reveal an intraocular mass with characteristics suggestive of a specific tumor type.

Systemic tests

For patients with uveal melanoma, a complete physical examination, liver function tests, liver imaging test (ultrasound or magnetic resonance imaging), and chest x-ray is recommended and should be repeated on a six month basis by the patient’s oncologist. For patients with uveal metastases, a complete oncologic evaluation by the general oncologist is warranted. Breast cancer is the most common uveal metastasis. For patients

with retinoblastoma, cautious ocular and systemic care by an ocular oncologist and pediatric oncologist is warranted. For patients with leukemia and lymphoma, systemic evaluation by the oncologist is recommended. Ocular involvement with leukemia carries an extremely poor systemic prognosis. Retinovitreal lymphoma tends to be associated with central nervous system lymphoma while uveal lymphoma is associated with systemic lymphoma. For patients with phakomatoses, a multidisciplinary approach with neurologist, dermatologist, pediatrician, and ophthalmologist is recommended.

Differential diagnosis

●Uveitic glaucoma.

●Neovascular glaucoma from other causes.

●Hemolytic glaucoma.

●Iridocorneal endothelial syndrome.

●Endophthalmitis.

PROPHYLAXIS

Treatment of the tumor at an early stage is a good measure to prevent glaucoma. However, some treatments, especially charged particle radiotherapy and plaque radiotherapy, can eventually lead to glaucoma.

TREATMENT

Medical

The management of glaucoma secondary to intraocular tumors should depend upon the type of tumor. In cases of benign tumors, it is often appropriate to first treat the glaucoma medically. In cases of malignant tumors, it may be appropriate to first treat the tumor in hopes of relieving the glaucoma. In cases of uveal melanoma, melanocytoma, metastasis, and lymphoid infiltration, the glaucoma may resolve with the primary treatment of the tumor either by surgical resection, radiotherapy, or chemotherapy. If the glaucoma persists despite effective therapy, then medical management of the secondary glaucoma is warranted. Generally, antiglaucoma eyedrops and systemic carbonic anhydrase inhibitors are instituted as necessary.

Surgical

Most melanocytic iris tumors should be managed initially by periodic observation and any associated glaucoma should be managed medically. If the tumor shows evidence of growth or if the secondary glaucoma cannot be controlled, then surgical intervention should be considered. In cases of circumscribed tumors, excision of the tumor by a partial iridectomy or iridocyclectomy may improve the glaucoma but further medical treatment of the glaucoma may be necessary. Trabeculectomy should be avoided until all conservative methods, including argon laser trabeculoplasty and ciliary body destructive procedures are attempted. In the case of a diffuse iris melanoma with secondary glaucoma, enucleation is generally necessary. Fine needle aspiration biopsy is indicated to differentiate melanoma from melanocytoma or nevus. We have found that open biopsy of an iris tumor or filtering surgery to control glaucoma in cases of diffuse iris melanoma can predispose to extrascleral extension of the tumor. In the case of iris melanocytoma, the liberated pigment in the trabecular meshwork may gradually disappear following complete excision of the main tumor.

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