Critical

Unilateral brown or translucent iris mass lesion exhibiting slow growth. It is more common in the inferior half of the iris and in light-skinned individuals. Rare in blacks (see Figure 5.13.1).

Other

A localized melanoma is usually >3 mm in diameter at the base and >1 mm in depth with a variable prominent feeder vessel. Can produce a sector cortical cataract, ectropion iridis, spontaneous hyphema, seeding of tumor cells into the anterior chamber, or direct invasion of tumor into the trabecular meshwork and secondary glaucoma. A diffuse melanoma causes progressive darkening of the involved iris, loss of iris crypts, and increased IOP. Focal iris nodules can be present.

Melanotic Masses

• Nevi: Typically become clinically apparent at puberty, usually flat or minimally elevated (i.e., <1 mm) and uncommonly exceed 3 mm in diameter. Can cause ectropion iridis, sector cortical cataract, or secondary glaucoma. Usually not vascular. More common in the inferior half of the iris. Nevi do not usually grow.
• Tumors of the iris pigment epithelium: Usually black in contrast to melanomas, which are often brown or amelanotic. Found on the posterior aspect of the iris.

Amelanotic Masses

• Metastasis: Grows rapidly. More likely to be multiple or bilateral than melanoma. Frequently liberates cells and produces a pseudohypopyon. Involves the superior and inferior halves of the iris equally.
• Leiomyoma: Transparent and vascular. Difficult to distinguish from an amelanotic melanoma.
• Iris cyst: Unlike melanoma, most transmit light with transillumination. Can arise from the iris pigment epithelium or within the iris stroma. Each with very different clinical features.
• Inflammatory granuloma: Sarcoidosis, tuberculosis, juvenile xanthogranuloma, and others. Often have other signs of inflammation such as keratic precipitates, synechiae, and posterior subcapsular cataracts. A history of iritis or a systemic inflammatory disease may be elicited. See Chapter 12, UVEITIS.

Diffuse Lesions

• Congenital iris heterochromia: The darker iris is present at birth or in early childhood. It is nonprogressive and usually is not associated with glaucoma. The iris has a smooth appearance.
• Fuchs heterochromic iridocyclitis: Asymmetry of iris color, mild iritis in the eye with the lighter-colored iris, usually unilateral. Often associated with a cataract or glaucoma. See 12.1, ANTERIOR UVEITIS (IRITIS/IRIDOCYCLITIS).
• Iris nevus syndrome: Corneal edema, peripheral anterior synechiae, iris atrophy, or an irregular pupil can be present along with multiple iris nodules and glaucoma.
• Pigment dispersion: Usually bilateral. The iris is rarely heavily pigmented (although the trabecular meshwork can be), and iris transillumination defects are often present. See 9.10, PIGMENT DISPERSION SYNDROME/PIGMENTARY GLAUCOMA.
• Hemosiderosis: A dark iris can result after iron breakdown products from old blood deposits on the iris surface. Patients have a history of a traumatic hyphema or vitreous hemorrhage.
• Siderosis from a retained metallic foreign body.