Excerpt from Angioid Streaks

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Background

In 1889, Doyne first described angioid streaks in a patient with retinal hemorrhages secondary to trauma.¹ Later in 1892, Knapp named them angioid streaks because of their resemblance to blood vessels.² Angioid streaks result from pathological changes at the level of the Bruch membrane, which was confirmed histologically in the late 1930s.

Pathophysiology

Controversy about the pathophysiology of angioid streaks exists. In some diseases, including pseudoxanthoma elasticum (PXE) and Paget disease, the Bruch membrane may become calcified and brittle with subsequent development of cracks. However, cytoimmunochemistry and x-ray analysis had shown that the earliest abnormality in PXE was abnormal accumulation and metabolism of polyanions (ie, glycosaminoglycans, glycoproteins) within the Bruch membrane.

The lines of force within the eye resulting from the pull of intrinsic and extrinsic ocular muscles on the relatively fixed site of the optic nerve have been studied. Those lines of forces had the same configuration as the peripapillary interlacement and radial extensions of angioid streaks. Such forces acting on the Bruch membrane undoubtedly account for the configuration of the breaks. However, in sickle cell disease, Bruch membrane calcification is not a common part of the pathology.

It is believed that the pathology may be a combination of diffuse elastic degeneration of the Bruch membrane, iron deposition in elastic fibers from hemolysis with secondary mineralization, and impairment of nutrition because of sickling, stasis, and small vessel occlusion. Klien proposed a dual mechanism as a cause of these cracks in general, as follows: a primary abnormality of fibers of the Bruch membrane, and an increase in availability of metal salts or a tendency for their deposition, resulting in a secondary brittleness of the membranes.³

Frequency

United States

Not known

International

Not known

Mortality/Morbidity

Moderate-to-severe central visual loss is mainly related to foveal involvement with a dehiscence of the underlying Bruch membrane or a neovascular membrane formation under the retina. Choroidal neovascularization (CNV) is the major cause of vision loss and affects 70-86% of patients with angioid streaks.

Race

No racial predilection is present.

Sex

No sexual predilection exists.

Age

The age of onset is variable with the underlying etiology. In one study, the age of onset of 50 patients with angioid streaks was reported as follows:

• Patients with PXE present in the third decade with a mean age of 51.7 years.
• Patients with sickle cell disease tend to be in their second and third decades with a mean age of 41.7 years.
• Patients with Paget disease tend to be older at the time of diagnosis with a mean age of 67 years.
• Angioid streaks in patients with no systemic disease or with rare etiologies tend to present late in life with a mean age of 65.7 years. Rare etiologies include patients with peptic ulcer, diabetes, hypertension, arthritis, breast cancer, metastatic cancer, rheumatoid spondylitis, and heart disease.

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