Uvea

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Uvea

Normal Anatomy

I. The uvea is composed of three parts: iris, ciliary body, and choroid (Figs. 9.1 and 9.2).

A. The iris is a circular, extremely thin diaphragm separating the anterior or aqueous compartment of the eye into anterior and posterior chambers.

1. The iris can be subdivided from pupil to ciliary body into three zones (pupillary, mid, and root) and from anterior to posterior into four zones [anterior border layer, stroma (the bulk of the iris), partially pigmented anterior pigment epithelium (which contains the dilator muscle in its anterior cytoplasm and pigment in its posterior cytoplasm), and completely pigmented posterior pigment epithelium].

2. The sphincter muscle, neuroectodermally derived like the dilator muscle and pigment epithelium, lies as a ring in the pupillary stroma.

B. The ciliary body, contiguous with the iris anteriorly and the choroid posteriorly, is divisible into an anterior ring, the pars plicata (approximately 1.5 mm wide in meridional sections), containing 70–75 meridional folds or processes, and a posterior ring, the pars plana (approximately 3.5–4 mm wide in meridional sections).

1. The ciliary body is wider on the temporal side (approximately 6 mm) than on the nasal side (approximately 5 mm).

2. From the scleral side inward, the ciliary body can be divided into the suprachoroidal (potential) space, the ciliary muscles (an external longitudinal, meridional, or Brücke’s; a middle radial or oblique; and an internal circular or Müller’s), a layer of vessels, the external basement membrane, the outer pigmented and inner nonpigmented ciliary epithelium, and the internal basement membrane.

C. The largest part of the uvea, the choroid, extends from the ora serrata to the optic nerve.

1. The choroid nourishes the outer half of the retina through its choriocapillaris and acts as a conduit for major arteries, veins, and nerves.

2. From the scleral side inward, the choroid is divided into the suprachoroidal (potential) space and lamina fusca; the choroidal stroma, which contains uveal melanocytes, fibrocytes, occasional ganglion cells, collagen, blood vessels (outer or Haller’s large vessels and inner or Sattler’s small vessels), and nerves; the choriocapillaris (the largest-caliber capillaries in the body); and the outer aspect of Bruch’s membrane.

3. The choriocapillaris in the posterior region of the eye has a lobular structure, with each lobule fed by a central arteriole and drained by peripheral venules.

Fig. 9.1 Iris and ciliary body. A and B, The iris is lined posteriorly by its pigment epithelium and anteriorly by the avascular anterior border layer. The bulk of the iris is made up of vascular stroma. Considerable pigment is present in the anterior border layer and stroma in the brown iris (A), as contrasted to little pigment in the blue eye (B and C). The iris pigment epithelium is maximally pigmented in A–C; the color of the iris, therefore, is only determined by the amount of pigment in the anterior border layer and stroma. A–C: The ciliary body is wedge-shaped and has a flat anterior end, continuous with the very thin iris root, and a pointed posterior end, continuous with the choroid. (Courtesy of Dr. RC Eagle, Jr.)

Fig. 9.2 Choroid. A, The choroid lies between the sclera (blue in this trichrome stain) and the retinal pigment epithelium. Uveal tissue spills out into most scleral canals, as into this scleral canal of the long posterior ciliary artery. B, The choroid is composed, from outside to inside, of the suprachoroidal (potential) space and lamina fusca, the choroidal stroma (which contains uveal melanocytes, fibrocytes, collagen, blood vessels, and nerves), the fenestrated choriocapillaris, and the outer aspect of Bruch’s membrane. C, Whereas the normal capillary in the body is large enough for only one erythrocyte to pass through, the capillaries of the choriocapillaris—the largest capillaries in the body—permit simultaneous passage of numerous erythrocytes. The choriocapillaris basement membrane and associated connective tissue compose the outer half of Bruch’s membrane, whereas the inner half is composed of the basement membrane and associated connective tissue of the retinal pigment epithelium. Note that the pigment granules are larger in the retinal pigment epithelial cells than in the uveal melanocytes (see also Fig. 17.1C).

Congenital and Developmental Defects

Persistent Pupillary Membrane

I. Persistence of a pupillary membrane (Fig. 9.3), a common clinical finding, is caused by incomplete atrophy (resorption) of the anterior lenticular fetal vascular arcades and associated mesodermal tissue derived from the primitive annular vessel.

Incomplete persistence is the rule. Because the remnants represent fetal mesodermal tissue, they are nonpigmented except when attached to the anterior surface of the lens. The remnants may be attached to the iris alone (invariably to the collarette) or may run from the collarette of the iris to attach onto the posterior surface of the cornea, where occasionally there is an associated corneal opacity. Isolated nonpigmented or pigmented remnants may be found on the anterior lens capsule (“stars”) or drifting freely in the anterior chamber. Total persistence of the fetal pupillary membrane is extremely rare and usually associated with other ocular anomalies, especially microphthalmos.

Fig. 9.3 Persistent pupillary membrane (PPM). A, Massive PPM, extending from collarette to collarette over anterior lens surface. B, Photomicrograph shows vascular membrane extending across pupil in three-day-old premature infant.

II. Histologically, fine strands of mesodermal tissue are seen, rarely with blood vessels.

Persistent Tunica Vasculosa Lentis

I. Persistence of the tunica vasculosa lentis is caused by incomplete atrophy (resorption) of the fetal tunica vasculosa lentis derived posteriorly from the primitive hyaloid vasculature and anteriorly from the primitive annular vessel posterior to the fetal pupillary membrane.

Persistence of the posterior part of the tunica vasculosa lentis is usually associated with persistence of a hyperplastic primary vitreous, the composite whole being known as persistent hyperplastic primary vitreous (see Fig. 18.17), and may or may not be associated with persistence of the anterior part of the tunica vasculosa lentis. The entire tunica vasculosa lentis may persist without an associated primary vitreous. The condition is extremely rare, however, and is usually associated with other ocular anomalies (e.g., with the ocular anomalies of trisomy 13).

II. Histologically, fine strands of mesodermal tissue, usually with patent blood vessels, are seen closely surrounding the lens capsule. Persistence and hyperplasia of the primary vitreous may or may not be present.

Heterochromia Iridis and Iridum

Heterochromia iridum (see Chapter 17) is a difference in pigmentation between the two irises, as contrasted to heterochromia iridis, which is an alteration within a single iris.

Hematopoiesis

I. Hematopoiesis in the choroid is a normal finding in premature infants and even in full-term infants for the first 3–6 months of life (Fig. 9.4).

Hematopoietic tissue may occur abnormally in association with intraocular osseous metaplasia (the bone-containing marrow spaces), usually in chronically inflamed eyes in people younger than age 20 years. A fatty marrow is the rule after 20 years of age. However, hematopoiesis may occur in some cases at any age, especially after trauma.

Fig. 9.4 Hematopoiesis. A, Infant weighing 1070 g died on the first day of life. Photomicrograph shows choroid thickened by hematopoietic tissue. B, Increased magnification demonstrates blood cell precursors.

II. Histologically, hematopoietic tissue containing blood cell precursors is seen in the uvea.

Ectopic Intraocular Lacrimal

Gland Tissue

I. Tissue appearing histologically similar to lacrimal gland tissue has been found in the iris, ciliary body, choroid, anterior chamber angle, sclera, and limbus (Fig. 9.5).

Fig. 9.5 Ectopic intraocular lacrimal gland. A, Clinical appearance of ciliary body tumor that has caused a sector zonular dialysis. B, Grossly, a cystic ciliary body tumor is present. C, Histologic section shows an intrascleral and ciliary body glandular tumor. D, Increased magnification demonstrates the resemblance to lacrimal gland tissue. (Case presented by Dr. S Brownstein to the meeting of the Eastern Ophthalmic Pathology Society, 1983, and reported by Conway VH et al.: adapted and published courtesy of Ophthalmology 92:449. © Elsevier 1985.)

II. Histologically, the tissue resembles normal lacrimal gland tissue.

Congenital and Developmental Defects of the Pigment Epithelium

See Chapter 17.

Aniridia (Hypoplasia) of the Iris

I. Complete absence of the iris, called aniridia, is exceedingly rare. In almost all cases, gonioscopy reveals a rudimentary iris in continuity with the ciliary body (i.e., iris hypoplasia; Fig. 9.6; see also Figs. 2.19 and 16.5).

Aniridia is caused by point mutations or deletions affecting the PAX6 gene, located on chromosome 11p13. Abnormal tear film stability and meibomian gland dysfunction are associated with aniridia, and they correlate with the severity of the disease. Impression cytology has confirmed varying degrees of limbal stem cell deficiency in these patients.

Fig. 9.6 Hypoplasia of iris. A, Clinical appearance of inferior and slightly nasal, partial stromal coloboma. B, Histologic section of another case shows marked hypoplasia of the iris (c, cornea; s, sclera; l, lens; i, hypoplastic iris; cb, ciliary body).

II. Photophobia, nystagmus, and poor vision may be present.

III. Glaucoma is often associated with hypoplasia of the iris.

IV. Other ocular anomalies may be present—for example, central corneal thickness, dry eyes, cataract, absent fovea, small optic disc, peripheral corneal vascularization, and persistent pupillary membrane.

V. Aniridia may be associated with Wilms’ tumor (see section Other Congenital Anomalies in Chapter 2).

VI. The condition may be autosomal dominant or, less commonly, autosomal recessive.

VII. Histologically, only a rim of rudimentary iris tissue is seen.

Ectropion Uveae (Hyperplasia of Iris Pigment Border or Seam)

I. Two forms are found: congenital and acquired.

A. Congenital ectropion uveae (Fig. 9.7) results from a proliferation of iris pigment epithelium onto the anterior surface of the iris from the pigment border (seam or ruff), where the two layers of pigment epithelium are continuous.

1. Glaucoma is often present.

2. The condition may be an isolated finding or may be associated with neurofibromatosis, facial hemihypertrophy, peripheral corneal dysgenesis, or the Prader–Willi syndrome (approximately 1% of patients with Prader–Willi syndrome, a chromosome 15q deletion syndrome, have oculocutaneous albinism).
Histologically, flattened iris pigment epithelium lines the anterior surface of the involved iris, which may show increased neovascularization.

Fig. 9.7 Congenital ectropion uveae. A, At six months of age, infant was noted to have abnormal left eye. Here, at eight years of age, child has normal right eye but lighter left eye with ectropion uveae (B) and glaucoma. Filtering procedure was performed. C, Histologic section of iridectomy specimen shows a pigmented anterior iris surface. Case was previously mistakenly reported as iridocorneal endothelial syndrome. (Case 7 in Scheie HG, Yanoff M: Iris nevus (Cogan–Reese) syndrome: A cause of unilateral glaucoma. Arch Ophthalmol 93:963, 1975. © American Medical Association. All rights reserved.)

B. The more common form, acquired ectropion, is acquired and progressive, usually a result of iris neovascularization.

Peripheral Dysgenesis of the Cornea and Iris

See Chapter 8.

Coloboma

I. A coloboma (i.e., localized absence or defect) of the iris may occur alone or in association with a coloboma of the ciliary body and choroid (Fig. 9.8; see also Fig. 2.9).

A. Typical colobomas occur in the region of the embryonic cleft, inferonasally, and may be complete, incomplete (e.g., iris stromal hypoplasia; see Fig. 9.6A), or cystic in the area of the choroid.

B. Atypical colobomas occur in regions other than the inferonasal area.

C. Typical colobomas are caused by interference with the normal closure of the embryonic cleft, producing defective ectoderm.

The anterior pigment epithelium seems primarily to be defective. Iridodiastasis is a coloboma of the iris periphery that resembles an iridodialysis. In the ciliary body, mesodermal and vascular tissues that fill the region of the coloboma often underlie the pigment epithelial defect. The ciliary processes on either side of the defect, however, are hyperplastic. The mesodermal tissue may contain cartilage in trisomy 13 (see Fig. 2.9). Zonules may be absent so that the lens becomes notched, producing the appearance of a coloboma of the lens. The retinal pigment epithelium (RPE) is absent in the area of a choroidal coloboma but is usually hyperplastic at the edges. The neural retina is atrophic and gliotic and may contain rosettes. The choroid is partially or completely absent. The sclera may be thin or ectatic, sometimes appearing as a large cyst (see subsection Microphthalmos with Cyst in Chapter 14).

Fig. 9.8 Coloboma of iris and choroid. A, External and fundus pictures from right eye of same patient show microcornea and iris coloboma (left) and choroidal coloboma (right) with involvement of optic disc. B, Photomicrograph of another case shows an absent retinal pigment epithelium (RPE) and choroid. The atrophic neural retina (r) lies directly on the sclera (s) (v, vitreous). Coloboma (absence) of RPE is the primary cause of coloboma (absence) of choroid. C, Leukokoria (cat’s eye reflex) when patient looks down. (A, Courtesy of Dr. RC Lanciano, Jr.)

II. The extent of a coloboma of the choroid varies.

A. It may be complete from the optic nerve to the ora serrata inferonasally.

B. It may be incomplete and consist of an inferior crescent at the inferonasal portion of the optic nerve.

C. It may consist of a linear area of pigmentation or RPE and choroidal thinning in any part of the fetal fissure.

III. Colobomas may occur alone or in association with other ocular anomalies.

Approximately 8% of eyes with congenital chorioretinal coloboma contain a retinal or choroidal detachment.

IV. The condition may be inherited as an irregular autosomal-dominant trait.

V. Histology

A. The iris coloboma shows a complete absence of all tissue in the involved area.

Iris coloboma is often associated with heterochromia iridum.

B. The ciliary body coloboma shows a defect filled with mesodermal and vascular tissues (also cartilage in trisomy 13) with hyperplastic ciliary processes at the edges.

C. The choroidal coloboma shows an absence or atrophy of choroid and an absence of RPE with atrophic and gliotic retina, sometimes containing rosettes.

1. The RPE tends to be hyperplastic at the edge of the defect.

2. The sclera in the region is usually thinned and may be cystic; the cystic space is often filled with proliferated glial tissue, which may become so extensive (i.e., massive gliosis) as to be confused with a glial neoplasm.

Cysts of the Iris and Anterior Ciliary Body (Pars Plicata)

I. Iris stromal cysts (Figs. 9.9 and 9.10) resemble implantation iris cysts after nonsurgical or surgical trauma.

A. The cysts can become quite large and cause vision problems by impinging on the pupil; they may also occlude the angle and cause secondary closed-angle glaucoma.

Ultrasonographic biomicroscopy has shown that approximately 54% of “normal” patients may have asymptomatic ciliary body cysts.

B. The origin of the cysts is poorly understood, although evidence suggests a two-part derivation: a component from cells of the iris stroma and an epithelial component from nonpigmented neuroepithelial cells.

Rarely, an occult, intrauterine limbal perforation of the anterior chamber with a needle may occur during amniocentesis.

C. Histologically, the cysts are lined by a multilayered epithelium resembling corneal or conjunctival epithelium that may have goblet cells. The cysts usually contain a clear fluid surrounded by a layer of epithelium.

Fig. 9.9 Cyst of the iris. A, A bulge is present in the iris from the 9 to 10 o’clock position. The stroma in this area is slightly atrophic. B, Gonioscopic examination of the region clearly delineates a bulge caused by an underlying cyst of the pigment epithelium of the peripheral iris. C, Electron microscopy of iris epithelial cyst shows thin basement membrane (bm), apical adherens junction (arrow), and apical villi, which indicate polarization of cells in layer, like that of normal iris pigment epithelium, and the presence of glycogen (g), similar to normal iris pigment epithelium.

Fig. 9.10 A, Gross specimen shows clear cyst of pars plicata of ciliary body. B, Scanning electron micrograph of nonpigmented ciliary epithelial cyst present at anterior margin of pars plicata. C, Proliferating nonpigmented epithelial cells in cyst wall. Note thin basement membrane on one side (arrow) and poorly formed multilaminar basement membrane on the other. (A and B, Courtesy of Dr. RC Eagle, Jr.)

II. Iris or ciliary body epithelial cysts are associated with the nonpigmented epithelium of the ciliary body or the pigmented neuroepithelium on the posterior surface of the iris or at the pupillary margin.

A. With the possible exception of the development of a secondary closed-angle glaucoma or pupillary obstruction, the clinical course of the pigment epithelial cysts is usually benign.

Multiple iris and ciliary body pigment epithelial cysts may be found in congenital syphilis. Secondary closed-angle glaucoma frequently develops in these eyes. Rarely, plateau iris can be caused by multiple ciliary body cysts.

B. The cysts form as the posterior layer of iris pigment epithelium or the inner layer of ciliary epithelium proliferates.

Occasionally, a cyst may break off and float in the anterior chamber. The cyst may then implant in the anterior chamber angle, where it has occasionally been mistaken for a malignant melanoma. The cyst may also float freely, enlarge, and so obstruct the pupil that surgical removal of the cyst is necessary.

III. Histologically, the pigmented cysts are filled with a clear fluid and are lined by epithelial cells having all the characteristics of mature pigment epithelium.

Cysts of the Posterior Ciliary Body (Pars Plana)

I. Most cysts of the pars plana (Fig. 9.11) are acquired.

Fig. 9.11 Cyst of the pars plana. A, Histologic section shows a large cyst of the pars plana of the ciliary body. A special stain, which stains acid mucopolysaccharides blue, shows that the material in the cyst stains positively. B, If the section is first digested with hyaluronidase and then stained as in A, the cyst material is absent, demonstrating that the material is hyaluronic acid. C, Apical surface of nonpigmented epithelial layer (npe) of pars plana cyst. Note the presence of apical microvilli (v), dense apical attachments (arrows; zonula adherens prominent), and desmosomes (d) between adjacent cells. D, Apical surface of pigment epithelial layer (pe) of pars plana cyst. Note apical villi and apical attachments (arrow; d, desmosome). Nonpigmented ciliary epithelial cysts are common in the region of pars plicata. E, Gross, fixed specimen shows milky appearance of multiple myeloma cysts of the pars plicata and pars plana, shown with increased magnification in F. (E and F, Courtesy of Dr. RC Eagle, Jr.)

II. Pars plana cysts lie between the epithelial layers and are analogous to detachments (separations) of the neural retina.

Clinically, the typical pars plana cysts and those of multiple myeloma appear almost identical. With fixation, however, the multiple myeloma cysts turn from clear to white or milky (see Fig. 9.11E and F), whereas other cysts remain clear. The multiple myeloma cysts contain γ-globulin (immunoglobulin). Cysts similar to the myeloma cysts but extending over the pars plicata have been seen in nonmyelomatous hypergammaglobulinemic conditions.

III. Histologically, large intraepithelial cysts are present in the pars plana nonpigmented ciliary epithelium. The nonmyelomatous cysts appear empty in routinely stained sections but are shown to contain a hyaluronidase-sensitive material when special stains are used to demonstrate acid mucopolysaccharides.

Inflammations

See Chapters 3 and 4.

Injuries

See Chapter 5.

Systemic Diseases

Diabetes Mellitus

See sections Iris and Ciliary Body and Choroid in Chapter 15.

Vascular Diseases

See section Vascular Diseases in Chapter 11.

Solitary spindle-cell xanthogranuloma (SCXG), another of the non-Langerhans’ cell histiocytoses, may involve the eyelids and contains Touton giant cells, but it differs from JXG in containing more than 90% spindle cells. SCXG may be an early form of JXG.

B. The skin lesions may predate or postdate the ocular lesions or occur simultaneously.

Fig. 9.12 Juvenile xanthogranuloma (JXG). A, Patient has multiple orange-skin lesions (biopsy-proved JXG) and involvement of both irises. Hyphema in right eye resulted in glaucoma and buphthalmos. B, Another patient shows a superior limbal epibulbar orange mass of the right eye that was sampled for biopsy. C, Histologic section shows diffuse involvement of the conjunctival substantia propria by histiocytes and Touton giant cells (see also Fig. 1.21). D, Oil red-O shows positive lipid staining of peripheral cytoplasm of Touton giant cell. (A, Courtesy of Dr. HG Scheie; Case in B–D presented by Dr. M Yanoff to the meeting of the Eastern Ophthalmic Pathology Society, 1993, and reported in Yanoff M, Perry HD: Juvenile xanthogranuloma of the corneoscleral limbus. Arch Ophthalmol 113:915, 1995. © American Medical Association. All rights reserved.)

II. Ocular findings include mainly diffuse or discrete iris involvement and occasionally ciliary body and anterior choroidal lesions, epibulbar involvement, corneal lesions, nodules on the lids, and orbital granulomas.

A. Most ocular lesions occur unilaterally in the very young, most younger than six months of age. Rarely, a limbal nodule can occur in an adult.

B. The iris lesions are quite vascular and bleed easily.

When confronted with an infant who has a spontaneous hyphema, the clinician must consider JXG along with retinoblastoma, medulloepithelioma, and trauma (the parents may think that the hemorrhage was spontaneous, but unknown trauma could have caused it).

III. JXG is separate from the group of nonlipid reticuloendothelioses called Langerhans’ granulomatoses or histiocytosis X (eosinophilic granuloma, Letterer–Siwe disease, and Hand–Schüller–Christian disease; see discussion of reticuloendothelial system in subsection Primary Orbital Tumors in Chapter 14).

IV. Histologically, a diffuse, often vascular, granulomatous inflammatory reaction with many histiocytes and often with Touton giant cells is seen (Touton giant cells may also be found in necrobiotic xanthogranuloma and liposarcoma).

JXG may be confused histologically with necrobiosis lipoidica diabeticorum, granuloma annulare, erythema induratum, atypical sarcoidosis, Erdheim–Chester disease, Rothman–Makai panniculitis, foreign-body granulomas, various xanthomas, nodular tenosynovitis, and the extra-articular lesions of proliferative synovitis.

Langerhans’ Granulomatoses (Histiocytosis X)

See discussion of reticuloendothelial system in subsection Primary Orbital Tumors in Chapter 14.

Collagen Diseases

See subsection Collagen Diseases in Chapter 6.

Mucopolysaccharidoses

See Chapter 8.

Atrophies and Degenerations

See subsections Atrophy and Degeneration and Dystrophy in Chapter 1.

Iris Neovascularization (Rubeosis Iridis)

See Figs. 9.13 and 9.14; see also Fig. 15.5.

Fig. 9.13 Iris neovascularization (IN). A, Early stage of IN in partially open angle. B, Histologic section of another case that had a central retinal vein occlusion, IN, and secondary glaucoma. Gonioscopy showed angle partially closed. Eye was enucleated. Histologic section shows apparent open angle. Closer examination reveals material in angle and other evidence that the posterior trabecular meshwork had been closed before enucleation, but fixation caused an artifactitious opening of the angle. C, The same region shown with a thin plastic-embedded section clearly demonstrates IN and closure of the posterior trabecular meshwork. (A, Courtesy of Dr. HG Scheie.)

Fig. 9.14 Iris neovascularization (IN). A, Significant IN extends to the pupillary margin (and had closed the angle). B, Gonioscopy of another case shows vessels climbing angle wall and a red line of vessels on posterior trabecular meshwork. The angle is closed to the left. C, Histologic section shows IN completely occluding angle. D, Thin section shows early IN partially occluding angle.

The term rubeosis iridis means “red iris” and should be restricted to clinical usage; iris neovascularization is the proper histopathologic term.

I. Causes include vascular hypoxia (central retinal vein occlusion, central retinal artery occlusion, temporal arteritis, aortic arch syndrome, carotid artery disease, retinal vascular disease, and ocular ischemic syndrome), neoplastic (uveal malignant melanoma, retinoblastoma, metastatic uveal tumors, and embryonal medulloepithelioma), inflammatory (chronic uveitis, post retinal detachment surgery, postradiation therapy, fungal endophthalmitis, and post-traumatic), and neural diseases (diabetic retinopathy, chronic neural retinal detachment, Coats’ disease, chronic glaucoma, sickle-cell retinopathy, Eales’ disease, persistent hyperplastic primary vitreous, Leber’s miliary microaneurysms, and Norrie’s disease).

II. Iris neovascularization may be induced by hypoxia, by products of tissue breakdown, or by a specific angiogenic factor. Neovascularization of the iris is always secondary to any of a host of ocular and systemic disorders.

III. Neovascularization often starts in the pupillary margin and the iris root concurrently, but it can start in either place first; the mid stromal portion is rarely involved early.

Early iris neovascularization in the angle does not cause synechiae and a closed angle but, rather, a secondary open-angle glaucoma, owing to obstruction of outflow by the fibrovascular membrane. Synechiae are rapidly induced, and chronic secondary closed-angle glaucoma ensues. Rarely, however, the rubeosis iridis involves the angle structures and anterior iris surface without causing synechiae, as may occur in Fuchs’ heterochromic iridocyclitis.

IV. A secondary closed-angle glaucoma (called neovascular glaucoma) and hyphema are the main complications of iris neovascularization.

Iris neovascularization is best differentiated from normal radial iris vessels by the random distribution found in iris neovascularization. Fluorescein angiography can be helpful in differentiating normal from abnormal iris vessels by demonstrating leakage from the abnormal vessels.

V. Histologically, fibrovascular tissue is found almost exclusively on the anterior surface of the iris and in the anterior chamber angle.

A. The blood vessels are derived initially from the ciliary body near the iris root or from iris stromal blood vessels.

B. The new vascular growth seems to leave the iris stroma rapidly (most commonly toward the pupil) to grow on and over the anterior surface of the iris.

With contracture of the myoblastic component of the fibrovascular tissue, the pupillary border of the iris is turned anteriorly (ectropion uveae). Synechiae are characteristically only present in the area of the anterior chamber angle peripheral to the end of Descemet’s membrane. Therefore, they can be differentiated from such broad-based synechiae as may be caused by a persistent flat chamber, chronic closed-angle glaucoma, or iris bombé.

Choroidal Folds

I. The condition consists of lines, grooves, or striae, often arranged parallel and horizontally. Occasionally, the folds may be vertical, oblique, or so irregular as to resemble a jigsaw puzzle.

II. The folds appear as a series of light and dark lines, often temporal and confined to the posterior pole, rarely extending beyond the equator.

Fluorescein angiography shows a series of alternating hyperfluorescent (peaks of folds) and hypofluorescent (valleys of folds) streaks that start early in the arteriovenous (AV) phase, persist through the late venous phase, and do not leak. The hyperfluorescent areas may be the result of RPE thinning or atrophy. The hypofluorescent areas may be caused by an inclination of the RPE in the valleys, which results in increased RPE thickness blocking the choroidal fluorescence, or may be caused by a partial collapse of the choriocapillaris in the valleys. Choroidal folds are differentiated from neural retinal folds by the latter’s finer appearance and normal fluorescein pattern.

III. Causes of choroidal folds include hypermetropia, macular degeneration, neural retinal detachment, hypotony, trauma, orbital tumors, thyroid disease, scleritis, uveitis, and others, including no known cause.

IV. Histologically, the choroid and Bruch’s membrane are corrugated or folded. RPE involvement seems to be a secondary phenomenon.

Heterochromia

See subsection Heterochromia Iridis and Iridum, this chapter, and Chapter 17.

Macular Degeneration

See Chapter 11.

Dystrophies

Iris Nevus Syndrome

See Chapter 16.

Chandler’s Syndrome

See Chapter 16.

Essential Iris Atrophy

See Chapter 16.

Iridoschisis

See Chapter 16.

Choroidal Dystrophies

I. Regional choroidal dystrophies

A. Choriocapillaris atrophy involving the posterior eyegrounds

1. Involvement of the macula alone [central areolar choroidal sclerosis (Fig. 9.15), central progressive areolar choroidal dystrophy, central choroidal angiosclerosis]

a. The condition probably has an autosomal (recessive or dominant) inheritance pattern and is characterized by the onset of an exudative and edematous maculopathy in the third to the fifth decade.

Autosomal-dominant central areolar sclerosis is caused by an Arg-142-Trp mutation in the peripherin/RDS gene. Other mutations that code to the peripherin/RDS gene include retinitis pigmentosa, macular dystrophy, pattern dystrophy, and fundus flavimaculatus.

b. Typical slow progression leads to a sharply demarcated, atrophic appearance involving only the posterior pole area, causing a central scotoma without night blindness.

Clinically, the condition may be indistinguishable from geographic RPE atrophy of age-related macular degeneration.

c. Histologically, the area of involvement shows an incomplete or complete loss of the choriocapillaris, the RPE, and the outer retinal layers.

Fig. 9.15 Central areolar choroidal sclerosis. A, Clinical appearance (left eye) of fundus in patient who had bilateral symmetric macular lesions. B, Histologic section of another case shows that the retinal pigment epithelium (RPE) and neural retina, which are relatively normal on the far left, show an abrupt transition to a chorioretinal abnormality that involves the outer neural retinal layers, RPE, and choroid. C, Increased magnification of the transition zone shows an intact Bruch’s membrane but loss of photoreceptors and RPE and obliteration of the choriocapillaris; no blood-containing vessels are seen in the remainder of choroid (r, neural retina; rpe, retinal pigment epithelium; ee, end of retinal pigment epithelium; er, end of retinal receptors). (A, Courtesy of Dr. WE Benson; B and C, Modified from Ferry AP, Llovera I, Shafer DM: Central areolar choroidal dystrophy. Arch Ophthalmol 88:39, 1972. © American Medical Association. All rights reserved.)

2. Involvement of the peripapillary area—peripapillary choroidal sclerosis

a. The area of involvement, mainly the posterior one-third of the globe surrounding the optic nerve, shows a sharply demarcated atrophic area and easily seen, large choroidal vessels.

b. Histologically, the area of involvement shows absence of choriocapillaris, RPE, and photoreceptors and a decrease in choroidal arteries and veins. Bruch’s membrane is intact except for some breaks in the immediate peripapillary region. Angioid streaks may also be found.

3. Involvement of the paramacular area—also called serpiginous choroiditis or circinate choroidal sclerosis

a. The dystrophy, usually bilateral, is characterized by well-defined gray lesions seen initially at the level of the pigment epithelium, usually contiguous with or very close to the optic nerve.

1) Each new lesion remains stationary.

2) With healing, degeneration of the pigment epithelium, geographic atrophy of the choroid, or even subretinal neovascularization and subretinal scar formation (disciform macular degeneration) may occur.

b. The disease progress is away from the optic disc, with new attacks occurring in areas previously uninvolved.

c. Visual acuity is only affected if the central fovea is involved in an attack.

Rarely, the initial lesion, or the only lesion, may be in the macula. Tuberculous choroiditis may mimic serpiginous choroiditis.

d. Histologically, the choriocapillaris, the RPE, and the outer neural retinal layers are degenerated and sharply demarcated from adjacent normal chorioretinal areas. Diffuse and focal areas of round cell inflammation (mainly lymphocytes) may be found.

4. Involvement with nasal and temporal foci—also called progressive bifocal chorioretinal atrophy (PBCRA)

The gene for PBCRA has been linked to chromosome 6q near the genomic assignment for North Carolina macular dystrophy. The phenotype of PBCRA, although similar to North Carolina macular dystrophy, is quite distinct.

5. Involvement of the disc—also called choroiditis areata, circumpapillary dysgenesis of the pigment epithelium, and chorioretinitis striata

6. Malignant myopia (see Chapter 11)

II. Diffuse choroidal dystrophies

A. Diffuse choriocapillaris atrophy—also called generalized choroidal angiosclerosis, diffuse choroidal sclerosis, and generalized choroidal sclerosis

Histologically, the choriocapillaris, the RPE, and the outer neural retinal layers are degenerated.

B. Diffuse total choroidal vascular atrophy

1. Autosomal-recessive inheritance (carried on chromosome 10q26)—also called gyrate atrophy of the choroid

a. In gyrate atrophy, chorioretinal patches develop in the periphery (often with glistening crystals scattered at the equator), progressing more centrally than peripherally, and partially fusing.

b. Other ocular findings include posterior subcapsular cataracts and myopia, cystoid macular edema (well seen with OCT imaging), and, rarely, retinitis pigmentosa.

A peripapillary atrophy may develop simultaneously. In the final stage, all of the fundi except the macula may be involved so that the condition may resemble choroideremia.

c. Patients have hyperornithinemia (10- to 20-fold increased ornithine concentration in plasma and other body fluids), caused by a deficiency of the mitochondrial matrix enzyme ornithine-δ-aminotransferase (OAT). They may also show subjective sensory symptoms of peripheral neuropathy.

1) OAT catalyzes the major catabolic pathway of ornithine, which involves the interconversion of ornithine, glutamate, and proline through the intermediate pyrroline-5-carboxylate and requires pyridoxal phosphate (vitamin B₆) as coenzyme.

2) The OAT gene maps to chromosome 10q26, and OAT-related sequences have also been mapped to chromosome Xp11.3–p11.23 and Xp11.22–p11.21.

d. The condition becomes manifest in the second or third decade of life, slowly progresses, causing a concentric reduction of the visual field, leading to tunnel vision and ultimately to blindness in the fourth to seventh decade of life. Decreasing vision and night blindness are prominent symptoms, along with electrophysiologic dysfunction.

e. An arginine-restricted diet slows the progress of the condition, whereas creatine supplementation appears to have no effect.

f. Histologically, the iris, corneal endothelium, nonpigmented ciliary epithelium, and, to a lesser extent, photoreceptors show abnormal mitochondria. An abrupt transition occurs between the normal and the involved chorioretinal area; the latter shows near-total atrophy of the neural retina, RPE, and choroid.

2. X-linked inheritance—also called choroideremia, progressive tapetochoroidal dystrophy, and progressive chorioretinal degeneration (Fig. 9.16)

a. This condition is characterized by almost complete degeneration of the retina and choroid (except in the macula) in affected men. It becomes manifest in childhood and progresses slowly until complete at approximately 50 years of age.

b. The CHM gene (xq21.2) is responsible for choroideremia.

The fundus picture in carrier women resembles that seen in the early stages in affected men, namely degeneration of the peripheral RPE giving a salt-and-pepper appearance. Mutations can cause severe visual loss in female carriers. Fundus autofluorescence is helpful in making the diagnosis.

c. Component A (but not B) of Rab geranylgeranyl transferase appears to be deficient in choroideremia.

Transfer of the Rab geranylgeranyl depends on the participation of Rab escort proteins (REPs). REP-1 is produced by a gene on the X chromosome, which is defective in patients who have choroideremia.

d. Histologically, the choroid and RPEs are absent or markedly atrophic, and the overlying outer neural retinal layers are atrophic. Uveal vascular endothelial cell and RPE abnormalities may be found where uveal vessels still persist.

Fig. 9.16 Choroideremia. A, Appearance of right eye in male patient who had bilateral choroideremia. B, Peripheral fundus of female carrier shows peripheral pigmentation. C, Histologic section of another case shows the absence of RPE and atrophy of both the overlying neural retina and the underlying choroid (v, vitreous; r, atrophic retina; s, sclera; c, atrophic choroid). D, Electron micrograph shows choroidal vessel deep to choriocapillaris. Both endothelial (e) and pericyte (p) basement membranes are absent centrally. A small amount of fragmented basement membrane (arrow) persists on the left. (A, Courtesy of Dr. WE Benson; B, courtesy of Dr. G Lang; C, Presented by Dr. WS Hunter at the AOA-AFIP meeting, 1969; D, Modified from Cameron JD, Fine BS, Shapiro I: Histopathologic observations in choroideremia with emphasis on vascular changes of the uveal tract. Ophthalmology 94:187. © Elsevier 1987.)

III. All of the aforementioned choroidal entities, although usually called atrophies, should more properly be called dystrophies with secondary retinal changes; it is likely that the primary dystrophic abnormality resides in the choroidal vasculature or the RPE.

Tumors

Epithelial

I. Hyperplasias (see Chapter 1 and section Melanotic Tumors of Pigment Epithelium of Iris, Ciliary Body, and Retina in Chapter 17)

Occasionally, pseudoadenomatous hyperplasias may become extreme and produce masses that are noted clinically, either localized to the posterior chamber or, rarely, proliferated into the anterior chamber.

II. Benign adenoma of Fuchs (Fuchs’ reactive hyperplasia, coronal adenoma, Fuchs’ epithelioma, benign ciliary epithelioma; Fig. 9.17)

A. The small, age-related tumor is present in more than 25% of older people, is located in the pars plicata of the ciliary body, is benign, and is usually found incidentally when an enucleated globe is being examined microscopically.

B. It may rarely cause localized occlusion of the anterior chamber angle.

C. The tumor is proliferative rather than neoplastic—that is, a hyperplasia and not an adenoma.

D. Histologically, it is a benign proliferation of cords of the nonpigmented ciliary epithelium interspersed with abundant, amorphous, eosinophilic, acellular basement membrane material, acid mucopolysaccharides, and glycoproteins.

Fig. 9.17 Fuchs’ adenoma. A, The lesion is seen grossly as a white tumor in the pars plicata of the ciliary body. B, Histologic section shows a proliferation of nonpigmented ciliary epithelium that is elaborating considerable basement membrane material (i, iris; s, Schlemm’s canal; ce, proliferating ciliary epithelium; cb, ciliary body).

III. Medulloepithelioma (see Chapter 17)

Muscular

I. Leiomyomas—benign smooth-muscle tumors—may rarely occur in the iris, ciliary body, or choroid.

A. Leiomyomas have a predilection for women.

B. The tumors tend to affect the ciliary body and anterior choroid.

Many cases previously diagnosed as leiomyoma are probably melanocytic, rather than smooth muscle, lesions. It is difficult to differentiate a leiomyoma from an amelanotic spindle cell nevus and low-grade melanoma without the use of electron microscopy and immunohistochemical studies.

C. Electron microscopic criteria for smooth muscle cells include an investing thin basement membrane, plasmalemmal vesicles, plasmalemma-associated densities, and myriad longitudinally aligned, intracytoplasmic filaments with scattered associated densities—characteristics that allow for identification of the cells in less than optimally fixed tissue. In addition, immunohistochemical stains for muscle-specific antigen, smooth muscle actin, and vimentin are positive.

D. Mesectodermal leiomyoma (see Chapter 14)

1. This rare variant of leiomyoma, which microscopically resembles a neurogenic tumor, presumably originates from the neural crest.

2. Histologically (Fig. 9.18), widely spaced tumor cell nuclei are set in a fibrillar cytoplasmic matrix and may show immunoexpression of neural markers.

The tumors resemble ganglionic, astrocytic, and peripheral nerve tumors. The presence of a reticulum differentiates mesectodermal leiomyoma from astrocytic tumors, where the fiber is absent. Immunohistochemistry and electron microscopy are needed to differentiate the tumor from peripheral nerve tumors. The diagnosis is made when immunohistochemical and ultrastructural features of smooth muscle cells are found.

Fig. 9.18 Mesectodermal leiomyoma. A, A 47-year-old woman suspected of having a ciliary body melanoma. B, Histologic section shows large ciliary body tumor composed of widely spaced tumor cell nuclei in a fibrillar cytoplasmic matrix (shown under increased magnification in C). D, Electron microscopy shows a dense osmophilic structure called skeinoid fibers. (Case presented by Dr. J Campbell at the combined meeting of the Verhoeff and European Ophthalmic Pathology Societies, 1996; Case reported in Campbell RJ, Min K-W, Zolling JP: Skenoid fibers in mesectodermal leiomyoma of the ciliary body. Ultrastruct Pathol 21:559, 1997.)

E. Leiomyosarcoma has been reported as a rare iris neoplasm.

II. A rhabdomyosarcoma is an extremely rare tumor of the iris and is probably atavistic.

Vascular

I. True hemangiomas of the iris and ciliary body are extremely rare.

A. Presumed iris hemangioma has been reported in association with multiple central nervous system (CNS) cavernous hemangiomas and may represent a distinct form of phakomatosis.

II. Hemangioma of the choroid (Fig. 9.19)

A. Hemangioma of the choroid occurs in two types: circumscribed and diffuse.

1. Circumscribed is usually solitary and not associated with any systemic process.

2. Diffuse may rarely occur as an isolated finding but mostly is part of the Sturge–Weber syndrome (see Fig. 2.2).

B. Over long intervals of observation, choroidal hemangiomas may show slight enlargement.

C. Clinically, it presents as a circumscribed, orange-red mass that shows early fluorescence with fluorescein and indocyanine green. Subretinal fluid is quite common.

D. Histologically, the choroidal tumor shows large, dilated, blood-filled spaces lined by endothelium and sharply demarcated from the normal, surrounding choroid.

Fig. 9.19 Hemangioma of choroid. A, An elevated lesion, which shows a characteristic orange color, is seen in the inferior nasal macular region. B, A histologic section of another case shows a total retinal detachment (d) and an extensive hemangioma (h) of the choroid in the macular area. C, Increased magnification of the temporal edge of the hemangioma shows that it is blunted and well demarcated from the adjacent normal choroid to the left. D, Similarly, the nasal edge of the hemangioma is blunted and easily demarcated from the adjacent choroid. This hemangioma was not associated with any systemic findings; in Sturge–Weber syndrome, the choroidal hemangioma is diffuse and not clearly demarcated from the adjacent choroid.

III. Hemangiopericytoma

A. Hemangiopericytomas are much more common in the orbit (see Chapter 14) than intraocularly.

B. Histologically, well-vascularized spindle cell proliferation is present in the uvea in a sinusoidal pattern.

IV. Arteriovenular (AV) malformation of the iris

A. AV iris malformation, also called racemose hemangioma, is rare.

B. It consists of a unilateral continuity between an artery and a vein without an intervening capillary bed.

C. The lesion is benign and stationary.

Osseous

I. Choroidal osteoma (osseous choristoma of the choroid; Fig. 9.20)

A. This benign, ossifying lesion is found mainly in women in their second or third decade of life and is bilateral in approximately 25% of patients.

1. Growth may be seen in approximately 51% of cases with long-term follow-up.

2. An associated subretinal fluid, neovascularization, or hemorrhage may be present. Over 10 years, approximately 56% of all patients will have decreased vision to 20/200 or worse.

Choroidal osteomas may follow ocular inflammation, be associated with systemic illness, or be familial. Rarely, they may undergo growth or spontaneous involution. Bilateral osseous choristoma of the choroid has been reported in an eight-month-old girl.

B. The characteristic clinical findings include:

1. A slightly irregularly elevated, yellow-white, juxtapapillary choroidal tumor with well-defined geographic borders

2. Diffuse, mottled depigmentation of the overlying pigment epithelium and multiple small vascular networks on the tumor surface

C. The tumor is dense ultrasonically; tissues behind the tumor are silent.

Calcified tumors show a distinctive latticework pattern of reflectivity, similar to spongy bone, by Fourier-domain optical coherence tomography. Decalcification occurs over time in almost 50% of patients.

D. Histologically, mature bone with interconnecting marrow spaces is seen sharply demarcated from the surrounding choroid.

Fig. 9.20 Choroidal osteoma. A, The patient has an irregular, slightly elevated, yellow-white juxtapapillary lesion. Ultrasonography showed the characteristic features of bone in the choroid. B, A histologic section of another case shows that the choroid is replaced by mature bone that contains marrow spaces. (A, Courtesy of Dr. WE Benson; B, Presented by Dr. RL Font at the meeting of the Eastern Ophthalmic Pathology Society, 1976.)

Melanomatous

See Chapter 17.

Leukemic and Lymphomatous

I. Acute granulocytic (myelogenous; Fig. 9.21) and lymphocytic leukemias not infrequently have uveal, usually posterior choroidal, infiltrates as part of the generalized disease.

Specific esterase activity, as determined by using naphthol ASD-chloroacetate, is present exclusively in granulocytic cells, thus differentiating acute granulocytic from acute lymphocytic leukemia. Demonstrating specific esterase activity histologically is especially helpful in diagnosing leukemic infiltrates [called myeloid (granulocytic) sarcoma], particularly in the orbit, where granulocytic leukemic infiltrates may appear greenish clinically because of the presence of the pigment myeloperoxidase, and then are called chloromas.

A. Approximately 30% of autopsy eyes from fatal leukemic cases show ocular involvement, mainly leukemic infiltrates in the choroid. Also, 42% of newly diagnosed cases of acute leukemia show ocular findings, especially intraretinal hemorrhages, white-centered hemorrhages, and cotton-wool spots.

Rarely, the first sign of granulocytic leukemia relapse is ocular adnexal involvement.

B. Retinal hemorrhages are most likely to occur in patients who have both anemia and thrombocytopenia combined; when the two are severe (hemoglobin <8 g/100 ml and platelets <100,000/mm), retinal hemorrhages may occur in 70% of patients.

Fig. 9.21 Acute leukemia. A, A patient presented with a large infiltrate of leukemic cells positioned nasally in the conjunctiva of the right eye, giving this characteristic clinical picture. These lesions look similar to those caused by benign lymphoid hyperplasia, lymphoma, or amyloidosis. B, A biopsy of the lesion shows primitive blastic leukocytes. C, In another case, the iris is infiltrated by leukemic cells. A special stain (Lader stain) shows that some of the cells stain red, better seen when viewed under increased magnification in D. This red positivity is characteristic of myelogenous leukemic cells.

II. Malignant lymphomas (see Chapter 14)—non-Hodgkin’s lymphoma of the CNS (NHL-CNS) and systemic non-Hodgkin’s lymphoma rarely involve the eye but do so much more often than Hodgkin’s lymphoma.

A. NHL-CNS—old terms—reticulum cell sarcoma, histiocytic lymphoma, microgliomatosis

1. NHL-CNS (Fig. 9.22), usually a large B-cell lymphoma, may be associated with similar multifocal neoplastic infiltrates in the vitreous, presenting clinically as uveitis.

Occasionally, NHL-CNS may involve the eye primarily and simulate a chronic uveitis, often with a vitreitis. Concentrations of interleukin-10 from vitreous aspirates may be helpful in making the diagnosis.

a. Vitreoretinal lymphoma is a rare subtype of primary CNS lymphoma.

b. The retina and choroid may also be involved (oculocerebral non-Hodgkin’s lymphoma).

c. The neoplasm probably arises in the brain and eye as a result of multicentric origin rather than by metastasis.

NHL-CNS is composed completely of B lymphocytes 70% of the time, T lymphocytes 20% of the time, and true histiocytes less than 10% of the time. When the neoplasm arises multicentrically in subretinal pigment epithelial space, it produces multiple, large, solid detachments of RPE that are characteristic.

Fig. 9.22 Non-Hodgkin’s lymphoma of the central nervous system (“reticulum cell sarcoma”). Patient treated for postoperative uveitis of both eyes for more than 12 months until central nervous system symptoms developed. A, The gross specimen shows a cloudy and prominent vitreous and a partial posterior vitreous detachment (c, cornea; pp, pars plana ciliary body; v, vitreous; s, sclera; r, retina). B, The vitreous is partially detached posteriorly and contains many cells (acid mucopolysaccharide stain). C, Increased magnification shows non-Hodgkin’s malignant lymphoma cells in vitreous. D, Plastic-embedded thin section of brain biopsy shows infiltration with non-Hodgkin’s malignant lymphoma cells. Malignant cells found only in brain and in vitreous of both eyes; no other tissues (including retina) involved. (Case contributed by Dr. EK Rahn; presented by Dr. M Yanoff at the meeting of the Verhoeff Society, 1974).

2. Systemic spread outside the CNS and eyes is found in only 7.5% of autopsies.

B. Systemic non-Hodgkin’s lymphoma

1. Systemic non-Hodgkin’s lymphoma almost always arises outside the CNS.

2. Ocular involvement occurs through invasion of choroidal circulation and spreads to the choroid.

3. Patients who have systemic non-Hodgkin’s lymphoma (as well as Hodgkin’s lymphoma) often have concurrent signs and symptoms of a systemic lymphoma at the time of ocular involvement and pose less of a diagnostic dilemma than NHL-CNS.

4. Rarely, adult T-cell lymphoma/leukemia (caused by human T-lymphotropic virus type 1 infection) presents as an intraocular lymphoma.

III. Occasionally, benign lymphoid infiltration (lymphoid tumor), containing lymphocytes, plasma cells, and reticulum cells, may be seen in the uveal tract.

A. The infiltrates are usually unilateral but may be bilateral. The infiltrates may appear as multifocal, confluent and nonconfluent, creamy choroidal patches that collect fluorescein without leakage into the subneural retinal or subretinal pigment epithelial spaces.

B. They resemble the inflammatory pseudotumors, especially reactive lymphoid hyperplasia (see Chapter 14), seen in the orbit.

Probably, uveal lymphoid infiltration (benign lymphoid hyperplasia of the uvea) is a low-grade B-cell lymphoma, which can be associated with episcleral conjunctival nodules.

Other Tumors

I. Neural

A. Neurofibromas of the uvea occur as part of diffuse neurofibromatosis (see Chapter 2).

B. Neurilemmomas (see Chapter 14) and glioneuromas (see Chapter 17) are exceedingly rare tumors of the uveal tract.

II. Benign fibrous tumor is exceedingly rare.

III. PTEN hamartoma tumor syndrome (PHTS)

A. Autosomal-dominant disorder caused by various mutations in tumor-suppressor gene phosphatase and tensin homolog (PTEN), located at 10q23.

B. Major diagnostic criteria are macrocephaly and breast and thyroid cancers; minor criteria include lipomas, fibrocystic breast disease, hamartomatous intestinal polyps, and fibromas.

C. Ocular findings include choroidal schwannoma, trichilemmomas, cataracts, conjunctival papillomas, retinal angiomas, and retinal coloboma.

Secondary Neoplasms

I. By direct extension:

A. Squamous (or rarely basal) cell carcinoma of conjunctiva

B. Malignant melanoma of conjunctiva

C. Retinoblastoma

D. Malignant melanoma of uvea (e.g., ciliary body melanoma extending into choroid or iris)

E. Embryonal and adult medulloepitheliomas

F. Glioma of optic nerve

G. Meningioma of optic nerve sheaths

It is extremely rare for an orbital neoplasm to invade through the sclera into the uvea or through the meninges into the optic nerve.

II. Metastatic—most common adult intraocular neoplasm (Fig. 9.23)

Although metastatic neoplasms are often considered to be the second most common intraocular neoplasm (second to primary uveal malignant melanomas), clinical and autopsy evidence suggests that metastatic cancer is the most common intraocular neoplasm.

A. Lung: most common metastatic lesion in both men and women (usually occurs early in the course of the disease and may be the initial finding).

B. Breast: second most common metastatic lesion in women (usually occurs late in the course of the disease and breast surgery was usually performed previously).

C. All other primary sites are relatively uncommon as sources of intraocular metastases.

D. Metastatic intraocular neoplasms are more common in women and are bilateral in approximately 20–25% of cases.

Although metastatic choroidal tumors tend to be oval-shaped clinically, rarely they may be mushroom-shaped and simulate a choroidal melanoma.

Fig. 9.23 Metastatic carcinoma. A, Note solid detachment thought to be malignant melanoma. B, Opened enucleated eye shows large amelanotic choroidal tumor on left. C, A histologic section shows dark and light areas. The dark areas represent the cellular tumor, and the light areas represent stroma. Even under low magnification, a choroidal malignant melanoma can be ruled out because a melanoma does not have any stroma. D, Increased magnification shows the malignant epithelial cells, many of which demonstrate mitotic figures.

Uveal Edema (Uveal Detachment; Uveal Hydrops)

Types

I. Uveal effusion syndrome—uveal effusion with choroidal and ciliary body detachment (spontaneous serous detachments)

A. Uveal effusion is characterized by a slowly progressive, often bilateral neural retinal detachment that shows shifting fluid and is mainly found in middle-aged, otherwise healthy men. Also noted are dilated episcleral vessels, vitreous cells, characteristic “leopard-spot” RPE changes, and abnormal ultrasonographic and angiographic findings.

Elevation of cerebrospinal fluid protein occurs in approximately 50% of cases. Although considered idiopathic, it may be caused by a congenital anomaly of the sclera and, in some cases, the vortex veins. The syndrome may also be found in nanophthalmic eyes and in patients who have primary pulmonary hypertension and vomiting.

B. Choroidal effusion is presumably the underlying cause and results from the thickened sclera and vortex vein anomalies. Signs of uveitis are minimal or absent.

C. Scleral abnormalities, secondary to proteoglycan deposition in the matrix, impede transscleral fluid outflow.

D. The neural retinal detachment may reattach after months or even years, although it may remain permanently detached.

II. Post-trauma—either surgical or nonsurgical trauma

A. Hypotony and vasodilatation after penetration of the globe combine to produce transudation of fluid through uveal vessels, leading to uveal edema. Clinically, this appears as a combined detachment of uveal tract and retina.

B. Uveal hemorrhage may occur secondary to the trauma and result in uveal detachment.

III. Vascular—malignant hypertension, eclampsia, nephritis, and other conditions that affect the ciliary vessels can lead to uveal edema.

IV. Inflammatory—any type of ocular inflammation (i.e., acute, nongranulomatous, or granulomatous—e.g., Harada’s disease) can induce uveal edema.

V. Associated with malignant choroidal tumors—for example, metastatic choroidal tumors or choroidal melanomas.

VI. Sequelae—in atrophic eyes with or without shrinkage, secondary to any cause, traction bands and organized scar tissue may induce uveal detachment.

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