LEUKEMIC RETINOPATHY

Ocular involvement in leukemia occurs in approximately 80% of cases, although many are asymptomatic. The ocular manifestations of leukemia may be divided into three categories: leukemic infiltrates; secondary complications related to anemia, thrombocytopenia, and hyperviscosity; and opportunistic infections. The term “leukemic retinopathy” typically refers to the secondary manifestations of leukemia.

Symptoms

Individuals with leukemic retinopathy may be asymptomatic or complain of abrupt visual loss related to preretinal or intraretinal hemorrhage involving the macula. Occasionally, patients will report decreased vision as the initial manifestation of their leukemia.

Clinical Features

Preretinal and intraretinal hemorrhages are the most common retinal findings in patients with leukemia. A strong correlation exists between the level of thrombocytopenia and the presence of retinal hemorrhages. White-centered hemorrhages, cotton wool spots, and dilation of retinal veins may be manifestations of hyperviscosity and leukostasis. A minority of patients may develop venous stasis retinopathy and peripheral retinal neovascularization. Other findings include vitreous infiltration, optic nerve swelling, orbital inflammation with proptosis, and cranial neuropathies.

Opportunistic infections are common in patients who have become immunosuppressed as a result of leukemia or chemotherapy. Some of the more common infections involving the retina and choroid include cytomegalovirus, herpes simplex virus, toxoplasmosis, and various fungal organisms.

Ancillary Testing

The diagnosis of leukemic retinopathy is based on clinical examination.

Pathology/Pathogenesis

Leukemic infiltration may occur in the vitreous, optic disc, retina, and choroid (most common). The secondary manifestations of leukemia are related to the hematologic abnormalities induced by the leukemia—namely anemia, thrombocytopenia, and hyperviscosity. Whitecentered hemorrhages are commonly observed. Although it has been speculated that the white center may represent collections of abnormal white blood cells, it most likely is a fibrin-platelet aggregate that develops during the normal physiologic healing process after localized capillary rupture.

Treatment/Prognosis

The ocular manifestations of leukemia typically resolve with improvement of hematologic parameters after chemotherapy and/or radiation therapy. Primary ocular therapy is seldom required. Ocular radiation may be considered for ocular infiltrates that do not respond to systemic therapy. Treatment with use of the Nd:YAG laser may be performed in cases of persistent preretinal hemorrhage obscuring the macula.

Systemic Evaluation

Hematologic evaluation for hematocrit, leukocyte and platelet counts, and bone marrow biopsy for clinical staging and classification are mandatory.

Leukemic retinopathy with preretinal hemorrhage was observed in this 19-year-old man who presented with loss of vision in each eye. Examination revealed bilateral preretinal hemorrhages overlying the macula.

White-centered hemorrhages are commonly observed in patients with leukemia. White-centered hemorrhages have been described in association with anemia and thrombocytopenia.

He also had scattered intraretinal hemorrhages and a few white-centered hemorrhages. He subsequently was diagnosed with acute myelogenous leukemia.

Additional findings in patients with leukemia include cotton wool spots and venous dilation and tortuosity.

OCULAR ISCHEMIC SYNDROME

The ocular ischemic syndrome occurs when there is significant obstruction of blood flow to the eye. A 90% or greater stenosis in the carotid system is the most common cause, although ophthalmic artery obstruction may be responsible for a minority of cases. Men are affected twice as often as women, and the mean age is 65 years. Atherosclerosis involving the carotid artery is the major cause of the ocular ischemic syndrome.

Symptoms

The most common symptom is gradual onset of visual loss. Slow recovery of vision after light exposure may also occur. Patients may report amaurosis fugax. A dull ache in or around the eye occurs in about 40% of patients.

Clinical Features

Visual acuity at presentation is variable and may range from 20/20 to no light perception. Rubeosis iridis is visible at presentation in two thirds of eyes. Elevation of intraocular pressure may be present, if there is angle involvement, but elevated intraocular pressure is not invariable due to associated reduced aqueous production from ciliary body ischemia. Mild anterior chamber inflammation is common. The retinal arteries may be narrowed and the veins slightly dilated but not tortuous. Spontaneous arterial pulsations may be present. Retinal hemorrhages are common and usually observed in the midperiphery. Microaneurysms and cotton wool spots are seen less commonly. Optic disc neovascularization is present in 35% of eyes, and neovascularization elsewhere (NVE) in about 8%.

Ancillary Testing

Fluorescein angiography is helpful in making the diagnosis by demonstrating delayed and patchy choroidal filling and prolongation of the retinal arterial venous transit time. Angiography may also show staining of retinal vessels and leakage from microvascular abnormalities. Electroretinography demonstrates reduction or absence of the a- and b-wave amplitudes.

Pathology/Pathogenesis

The ocular ischemic syndrome is caused by reduced blood flow to the eyeball, producing both anterior and posterior segment ischemia. Retinal ischemia leads

to endothelial cell and pericyte damage, resulting in hemorrhage, macular edema, and retinal capillary nonperfusion.

Treatment/Prognosis

Panretinal photocoagulation is indicated in most cases when either anterior or posterior segment neovascularization is present. Glaucoma medication should be used to treat elevated intraocular pressure, and topical steroids and cycloplegics may be helpful when there is a significant anterior segment inflammatory response. The role of carotid endarterectomy is controversial and probably most helpful from an ocular standpoint if performed before the onset of rubeosis. It may also be helpful in reducing the risk of subsequent stroke. Visual prognosis is variable. Approximately 60% of patients have counting fingers or worse vision at the end of the 1-year follow-up. About 25% of patients retain better than 20/50 vision. The 5-year mortality rate for patients

with ocular ischemic syndrome is 40%, with the leading cause of death being cardiovascular disease.

Systemic Evaluation

A complete cardiovascular evaluation, with particular attention to causes of carotid obstructive disease, is recommended for all patients presenting with the ocular ischemic syndrome. A dissecting aneurysm of the carotid artery and temporal arteritis have been reported to cause ocular ischemic syndrome and should be included in

the workup.

Ocular ischemic syndrome is caused by insufficient blood flow to the eye. Many patients present with iris neovascularization. Patients with anterior chamber angle involvement may develop neovascular glaucoma.

Funduscopic examination usually reveals intraretinal hemorrhages. The retinal arteries are narrowed, and the veins may be slightly dilated.