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HEMATOLOGIC & LYMPHATIC DISORDERS

LEUKEMIA

The ocular changes of leukemia occur primarily in those structures with a good blood supply, including the retina, the choroid, and the optic disk (Figure 15-14). Changes are most common in the acute leukemias, where hemorrhages are seen in the nerve fiber and preretinal layers.

HYPERVISCOSITY SYNDROMES

Increased viscosity results in a reduced flow of blood through the eye. This produces a characteristic dilation of the retinal arteries and veins, hemorrhages, microaneurysms, and areas of capillary closure (Figure 15-15). Polycythemia, either primary or secondary, may produce a hyperviscosity syndrome; the other main causes are macroglobulinemia and multiple myeloma. Reduction of the abnormalities producing hyperviscosity can reverse the retinal changes.

SICKLE CELL DISEASE

Sickle cell hemoglobinopathies are heritable disorders in which the normal adult hemoglobin is replaced by sickle hemoglobin in the red cell. This causes "sickle-shaped" deformity of the red cell on deoxygenation.

Ocular abnormalities include conjunctival changes, with "comma-shaped capillaries," and retinal changes, including arterial occlusions and peripheral capillary closure which leads to new vessel formation, particularly a sea fan pattern. Retinal detachment may develop. Laser therapy is rarely needed, since the complexes fibrose and reperfusion can occur.

NEOPLASTIC DISEASE (  Figure 15-16)

Neoplastic disease may involve the eye and optic pathways by direct spread, by metastases, or by immunologic mechanisms.

The consequences of metastatic spread depend upon the size and site of the metastatic tumor and the site of the primary lesion. The most frequent primary tumor metastasizing to the eye is carcinoma of the breast in women and bronchial carcinoma in men. Visual loss may occur from nonmetastatic disease with consequent retinal degeneration. The syndromes are called cancer-associated retinopathy, melanoma-associated retinopathy, both associated with specific retinal autoantibody, and diffuse uveal melanocytic proliferation.

10.1036/1535-8860.ch15

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