MACULAR ATROPHY

Age-related macular degeneration

Presumed ocular histoplasmosis

Clinical Features

Macular atrophy is a nonspecific finding observed in a variety of macular, vascular, hereditary, toxic, inflammatory, and traumatic retinal disorders. Macular atrophy may be observed in the young and old, depending on the etiology. Individuals may be asymptomatic or complain of visual loss, distortion, or scotoma.

Macular atrophy is often bilateral but may be asymmetric or unilateral. Areas of macular atrophy may be confined to the macula or be associated with more widespread alterations. In many cases, the region of atrophy assumes a well-defined, geographic, “map-like” pattern. In areas of significant atrophy, the larger choroidal vessels are visible resulting from the loss of retinal pigment epithelium (RPE) and choriocapillaris. Macular atrophy may be associated with RPE alterations or fibrosis.

Differential Diagnosis

Stargardt disease

Degenerative myopia

with nonexudative AMD. The areas of geographic atrophy are well circumscribed, and often develop in a paracentral location before involving the fovea. Calcific drusen are often present. The etiology of geographic atrophy remains unclear but may involve abnormalities in the choroidal circulation.

Other conditions associated with macular atrophy include angioid streaks; central serous chorioretinopathy; myopic degeneration; long-standing cystoid macular edema from any cause; macular phototoxicity; pattern dystrophies; Best’ s disease and other familial macular dystrophies (North Carolina macular dystrophy; Sorsby’s macular dystrophy); choroideremia; cone dystrophy

and other causes of bull’s eye maculopathy; gyrate atrophy; and Stargardt disease. Macular atrophy may be observed in a variety of inflammatory (histoplasmosis, toxoplasmosis, multifocal choroiditis, serpiginous choroiditis) and traumatic (commotio retinae, choroidal rupture) disorders.

Cat scratch neuroretinitis

Cat scratch neuroretinitis. (Photograph courtesy Gary Miller, CRA.)

Clinical Features

The association of optic disc edema and macular star has been classified as neuroretinitis or Leber’s idiopathic stellate neuroretinitis. Patients present with varying degrees of unilateral visual loss; often the visual loss is preceded by a flu-like illness characterized by fevers and lymphadenopathy. Examination reveals an afferent pupillary defect and mild vitritis. Most patients demonstrate optic disc edema associated with fluid exudation from the optic disc through the foveal region. The macular star is formed by a radiating pattern of lipid and protein exudate extending from the optic disc. The star may be more prominent on the nasal aspect of the fovea (half star), and becomes more apparent as the fluid resorbs. The etiology of the star is unclear but most likely represents

protein and lipid deposition in Henle’s layer. It is important to recognize that the fluid in the macula is from the optic disc and not the result of primary retinal vascular abnormalities in the macula.

Differential Diagnosis

Most cases of unilateral optic disc edema and macular star are related to cat scratch disease. Other conditions include hypertension, Lyme disease, syphilis, tuberculosis, toxoplasmosis, polyarteritis nodosa, capillary angiomas of the optic disc, and other causes of disc edema (pseudotumor cerebri, intracranial arteriovenous malformation). It is important to assess blood pressure before proceeding with laboratory investigation.

Clinical Features

Peripheral pigmentation of the fundus may take on a variety of appearances. The most common pigmentary patterns are linear, granular, reticular, clumps, or bone spicule formation.

Differential Diagnosis

Pigmentary clumps and lines are commonly seen within areas of lattice degeneration. In retinitis pigmentosa, a branching or “bone spicule” pattern of peripheral pigmentation develops due to the migration of retinal pigment epithelial pigment along the retinal blood vessels. The pattern of pigment deposition in retinitis pigmentosa typically begins in the midperipheral retina and may

be quite subtle on presentation. Midperipheral retinal pigment is also seen in senile reticular pigmentary degeneration, a benign condition that is associated with

peripheral drusen and age-related macular degeneration. Most prominent in the nasal periphery, senile reticular pigmentary degeneration appears as a pigmentary pattern of clumps or branches.

Long-standing subretinal fluid from a chronic rhegmatogenous retinal detachment can cause peripheral pigment to accumulate along the line of detached and attached retina (a demarcation line). Chronic subretinal fluid from an exudative process such as idiopathic central serous chorioretinopathy can, because of gravity, cause a flask-shaped pattern of intraretinal pigment migration in the inferior macula.

Other less common causes of peripheral pigmentation include chloroquine toxicity, Stargardt disease, and pigmented paravenous retinochoroidal atrophy.

Age-related macular degeneration

Central serous chorioretinopathy

Clinical Features

The fundamental clinical feature of a pigment epithelial detachment (PED) is an oval or round elevation of the retinal pigment epithelium (RPE). The elevation is often quite subtle and may be seen only with stereoscopic examination of the macula. The three major types of PEDs—fibrovascular, hemorrhagic, and serous—are named according to the material that is primarily elevating the RPE.

Differential Diagnosis

A fibrovascular PED, a form of occult choroidal neovascularization (CNV), is an area of irregular elevation of the RPE. The fluorescein angiographic features of a fibrovascular PED include stippled hyperfluorescence in the midphase of the angiogram with late leakage or staining. A fibrovascular PED commonly occurs due to choroidal bleeding from occult CNV. A hemorrhagic PED is dark red or gray and, in patients with age-related macular degeneration (AMD), may have drusen on its surface. The differential diagnosis includes idiopathic

Age-related macular degeneration (fluorescein angiogram)

Polypoidal choroidal vasculopathy

polypoidal choroidal vasculopathy or posterior uveal bleeding syndrome. On the fluorescein angiogram, complete hypofluoresence corresponds to the area of hemorrhagic RPE detachment.

Serous PEDs may be seen in AMD and are frequently associated with CNV. On examination, the serous PED appears as a translucent elevation of the RPE with a smooth or dome-shaped surface. In a serous PED, the choroidal pattern is no longer visible and the fluorescein angiographic features consist of uniform filling of dye and persistent pooling of fluorescein throughout the angiogram. Serous pigment epithelial detachments

are seen in other conditions, most notably idiopathic central serous chorioretinopathy (ICSC). In ICSC, the serous PED is small and may be masked by the overlying subretinal fluid.

The differential diagnosis of pigment epithelial detachments includes choroidal hemangioma, choroidal melanoma, and subretinal fluid.