Ординатура / Офтальмология / Английские материалы / Handbook of Pediatric Retinal Disease_Wright, Spiegel, Thompson_2006

FIGURE 11-11A–C. (continued)

untreated, these lesions may progress to disciform scarring, although some resolve spontaneously with maintenance of good visual acuity. Submacular surgery to remove peripapillary and subfoveal choroidal neovascular membranes is sometimes used. Ablation of these neovascular membranes with argon laser has been shown to reduce the risk of severe visual loss in some patients.39 Photodynamic therapy is helpful in cases of subfoveal or juxtafoveal neurovascular memory.

SYMPATHETIC OPHTHALMIA

Sympathetic ophthalmia is an uncommon but potentially devastating ocular disease of unknown etiology. It is a bilateral granulomatous uveitis that occurs after penetrating trauma or, less commonly, after intraocular surgery. The disease is thought to represent an autoimmune response to an unidentified antigen. The inflammatory response occurs not only in the traumatized eye (exciting eye) but also in the fellow eye (sympathizing eye). The disease is more common in males. Children and young adults are most commonly affected, probably reflecting the

higher incidence of trauma in these age groups. Sympathetic ophthalmia is uncommon ( 1% of trauma cases and 0.05% of surgical cases).26 The incidence of sympathetic ophthalmia has apparently decreased over time, possibly because of advances in surgical technique.

The clinical course of sympathetic ophthalmia is variable. The onset may occur days or many years after the initial injury. Typically, there is a mild inflammatory response in the sympathizing eye with a worsening of inflammation in the exciting eye.43 The anterior chamber inflammation may be intense, with formation of keratic precipitates. Anterior chamber inflammation is accompanied by injection, pain, and photophobia. Vitritis and retinal changes typically follow. Yellow-white peripheral choroidal lesions are known as Dalen–Fuchs nodules, which are classic but not pathognomonic of the disease. Optic disc swelling is often seen (Fig. 11-12A). Pathologically, there is diffuse infiltration of the choroid with lymphocytes, epithelioid cells, and scattered giant cells (Fig. 11-12B). Dalen–Fuchs nodules represent focal accumulations of inflammatory cells beneath the RPE. The choriocapillaris is classically not involved in the inflammation.

The diagnosis of sympathetic ophthalmia is made clinically. Ultrasound demonstrates a thickened choroid. There are no laboratory tests that aid in the diagnosis. Fluorescein angiography shows multiple enlarging hyperfluorescent spots at the level of the RPE. Indocyanine green shows hypofluorescence.7a

Untreated, the disease tends to run a chronic destructive course. Before the the use of corticosteroids, less than 50% of patients retained any useful vision. The prognosis has improved with corticosteroid treatment, although many patients require long-term steroid treatment and the disease tends to recur when steroids are withdrawn.27 Enucleation of the injured eye before the development of inflammation in the fellow eye may prevent sympathetic ophthalmia. If an eye has no useful vision and is traumatically disorganized, it should probably be enucleated within 2 weeks of the injury to minimize the likelihood of sensitization to the antigen to which the inflammatory response occurs. It is unknown whether enucleation of the injured eye is beneficial after inflammation has begun in the sympathizing eye. Large doses of systemic corticosteroids are advisable in treating sympathetic ophthalmia in most cases. These doses may be necessary for many weeks. Once the inflammation has been controlled, one should attempt to taper the steroids slowly,

eventually using an alternate-day regimen with the lowest possible dose. Cyclosporine, methotrexate and alkylating agents such as chlorambucil are alternatives to steroids in refractory cases or in patients unable to tolerate corticosteroids.7a,43

VOGT–KOYANAGI–HARADA SYNDROME

The Vogt–Koyanagi–Harada syndrome (VKH) is a multisystem disorder with a predilection for darkly pigmented individuals and those of Asian ancestry. In the United States, it is most common in patients with Native American heritage. VKH occurs most commonly in the second to fifth decades of life. The disease has been termed the uveomeningitic syndrome because it classically presents with uveitis and a meningeal prodrome with headache, fever, neck stiffness, and CSF pleocytosis. Vitiligo, poliosis, alopecia, tinnitus, and neurosensory hearing loss may occur later in the course of the disease.

Ocular involvement usually begins as a posterior uveitis. Optic disc swelling and retinal edema occur early and, as the disease evolves, exudative retinal detachment may occur (Fig. 11-13A,B). Additional complications include cataract, glaucoma, choroidal neovascular membrane, and subretinal fibrosis.22,45

Fluorescein angiography will show characteristic leakage of fluorescein from the choroid (and not from the retinal vessels) at this stage. An anterior uveitis with keratic precipitates and iris nodules usually occurs later. Pathologically, there is invasion of the choroid with inflammatory cells similar to that seen in sympathetic ophthalmia. In contrast to sympathetic ophthalmia where the choriocapillaris is usually spared, the choriocapillaris is often involved in the inflammatory response in VKH.

The etiology of VKH is unknown. T-lymphocyte-mediated autoimmunity probably plays a role. The HLA-DR4 antigen is associated with VKH in Native American, Italian, Japanese, Chinese, and Hispanic patients.40

Corticosteroids are the drugs of choice in the treatment of VKH. High-dose oral or intravenous steroids may be necessary for severe cases with exudative retinal detachment. As a therapeutic response is obtained, the steroid dose may be tapered. The response to therapy is variable, and inflammation may recur

FIGURE 11-13A,B. Bilateral exudative retinal detachments in patient with Vogt–Koyanagi–Harada syndrome.

after steroids are stopped. Cyclosporine may be used in refractory cases or in patients who do not tolerate corticosteroids. Table 11-3 compares the clinical features of sympathetic ophthalmia and VKH syndrome.

Source: Power WJ, Foster CS. Update on Sympathetic Ophthalmia. Int Ophthalmol Clin 1995;35:127–137, with permission.43

VITAMIN A DEFICIENCY

Depletion of tissue stores of vitamin A leads to an ocular syndrome characterized by night blindness and xerophthalmia. Vitamin A is a fat-soluble vitamin found in meat, eggs, and milk. Carotenes can be metabolized to vitamin A in humans, and thus yellow fruits and green leafy vegetables are also important sources of Vitamin A. Hypovitaminosis A is an important problem in Third World countries. It is uncommon in the United States but can occur in malnourished patients, those with malabsorption disorders, and patients on abnormal diets.

Nyctalopia (night blindness) is the earliest and most common manifestation of vitamin A deficiency. In untreated cases, the conjunctiva becomes dry (xerosis) and Bitot’s spots (plaques of keratinizing debris at the limbus) appear (Fig. 11-14). Corneal drying occurs and may progress to ulceration with resultant blindness. Fundus changes consisting of peripheral yellow-white dots may occur, but this is uncommon.

The diagnosis is usually made clinically. Dark adaptation is characteristically prolonged. Serum vitamin A levels may be abnormal, but this is a late occurrence because serum levels may be normal in the face of severe tissue depletion of the vitamin. Treatment of the condition is systemic replacement of vitamin A. The prognosis for vision depends on the state of the ocular tissues at the time therapy is instituted. Healing of corneal and conjunctival lesions will occur, but in cases where perforation has occurred, vision may not be restored. Artificial tears, topical

FIGURE 11-14. Bitot’s spot in a patient with vitamin A deficiency. These whitish, poorly wetting patches are seen early in the course of the disease. Progression to severe xerosis may occur in untreated cases.

antibiotics, and topical retinoic acid may be of some adjunctive use in therapy.52 Bitot’s spots do not respond to systemic therapy and may require excision.

SIDEROSIS AND CHALCOSIS (RETAINED METALLIC FOREIGN BODIES)

Intraocular foreign bodies containing iron or copper may not cause an immediate severe inflammatory reaction and may not be recognized by the patient or a physician at the time of initial trauma. However, their presence may lead to severe consequences at a later time.

Siderosis is produced by oxidation of iron to ferrous (Fe2 ) ions with absorption of these toxic ions by various ocular tissues. Iron may accumulate in the iris causing heterochromia and pupillary sphincter palsy. Rust spots may appear on the lens, and a cataract may form (Fig. 11-15A,B). Glaucoma may result from accumulation of iron in the trabecular meshwork. Retinal toxicity results in ERG changes beginning with an increase in the height of the a-wave followed by a decrease in the height of both the a-wave and the b-wave. The ERG may eventually

become flat (Fig. 11-15C). Even at this point, removal of the foreign body may be indicated as useful vision may remain.

Pure copper is extremely toxic to the eye, and a pure copper intraocular foreign body may cause an acute suppurative endophthalmitis. Foreign bodies containing small amounts of copper typically will not cause such an acute inflammatory response. However, copper ions may, over time, be disseminated throughout the eye, leading to a syndrome known as chalcosis. Copper ions have an affinity for basement membranes. Deposits of copper in the lens capsule may lead to a “sunflower” cataract. Deposits in Descemet’s membrane lead to the formation of the characteristic Kayser–Fleischer ring, a golden-colored corneal ring at the limbus. There may be iris heterochromia with a greenish tint to the iris in the involved eye. Retinal toxicity is much less severe than that seen in siderosis. A small decrease in the height of the b-wave may be seen. Macular pigmentary changes have been described. Visual loss may result from cataract formation or vitreous changes.49 The decision as to whether a copper-containing foreign body should be removed in patients with chalcosis should be individualized.

All patients with a history consistent with the possibility of an intraocular foreign body should have appropriate radiologic studies at the time of their presentation.

ACUTE POSTERIOR MULTIFOCAL PLACOID PIGMENT EPITHELIOPATHY

In 1968, Gass described a syndrome of temporary loss of vision associated with large plaquelike lesions at the level of the retinal pigment epithelium and termed this disorder acute posterior multifocal placoid pigment epitheliopathy (APMPPE). This disorder is typically bilateral but may not affect both eyes at the

FIGURE 11-15A–C. (A) “Rust spots” beneath the anterior capsule of the lens are a typical feature of siderosis in a patient with a retained ironcontaining foreign body. (B) Retained metallic foreign body seen in the same patient. Note the hazy vitreous and pigmentary retinal abnormalities. (C) Electroretinogram (ERG) shows somewhat selective loss of the b-wave amplitude in the right eye (top tracing) in a patient with a metal foreign body and signs of siderosis.