Histologically, conjunctival, and scleral specimens from patients with syphilitic scleritis in any stage of the disease show a plasma cell inÞltration with scattered macrophages and lymphocytes. Arterioles in the inßammatory reaction may exhibit swelling and proliferation of endothelial cells to produce concentric ÒonionskinÓ layers that markedly narrow the lumen, leading to an obliterative endarteritis [169, 170]. Around these vessels there is prominent perivascular cufÞng by plasma cells. Tertiary and late congenital syphilis may also show gummas, which consist of granulomas with coagulated necrotic centers surrounded by macrophages and plasma cells, similar to tuberculous lesions [171]. Because treponemes may be scant in sclera, their identiÞcation with silver stains (LevaditiÕs stain or WarthinÐStarry stain) or by immunological methods (direct or indirect immunoßuorescence or immunoperoxidase testing) may be difÞcult [172Ð175]. When scleral treponemes cannot be demonstrated, the presumed diagnosis of syphilitic scleritis is based on the histological conjunctival or scleral inßammatory reaction with obliterative endarteritis, associated with a positive serological FTA-ABS. We have used indirect immunoßuoresce testing in an attempt to demonstrate T. pallidum in scleral specimens (rabbit antitreponemal antibody and ßuoresceinlabeled sheep anti-rabbit antibody) [161], but our results have been negative.

Local Infections

Exogenous infectious scleritis is rare, probably because of the tightly bound collagen Þbers of the scleral coat. When it occurs, however, it is usually the result of scleral extension of a primary corneal infection. However, primary scleral infections may occur following accidental or surgical injury (pterygium excision with § irradiation or topical thiotepa, retinal detachment repair with diathermy, or strabismus surgery) [133] or as a result of a retained intrascleral foreign body [13]. Cultures of corneal or scleral scrapings may demonstrate the microorganism implicated. Analysis of conjunctival and scleral specimens

by light microscopy and appropriate stainings may show the etiological agents [129, 130, 135], and subsequent culture of the tissues may help in further identiÞcation. Aside from detection of the microorganism, conjunctival and scleral specimens disclose abundant hemorrhage and acute inßammatory, cell inÞltration, which may lead to tissue necrosis [130Ð132, 135].

We use GramÕs stain (bacteria and fungus), Gomori methenamine silver (fungus), WarthinÐ Starry silver stain (spirochete), acid-fast stain (mycobacteria), and calcoßuor white stain (Acanthamoeba) on histopathological preparations to detect the presence of infectious agents. Alkaline Giemsa can show the presence of viral cytoplasmic or intranuclear inclusion bodies and the morphology of bacteria and fungi. We also use tissue culture techniques for microbe isolation. Scleral specimens are placed in 1 ml of meat broth and homogenized with a tissue grinder (Sage Products, Inc., Cary, IL). One-drop samples are cultured on blood agar (room temperature and 37¡C, aerobic and anaerobic), chocolate agar (37¡C), Sabouraud dextrosa agar (room temperature), and meat broth (37¡C) to identify bacteria and fungi. Culture for Acanthamoeba requires placing the sample in PageÕs saline and transferring it to conßuent layers of Escherichia coli (25 and 37¡C). Homogenates also may be placed on cell culture lines, such as HeLa cells, human amnion cells, and human Þbroblasts to identify HSV type 1 (cytopathic effect), and human embryonic lung diploid cells, human fetal diploid kidney cells, or human foreskin Þbroblasts to identify VZV (cytopathic effect). An illustrative case is described:

A 67-year-old white male, while working on his farm, was struck in the right eye by a cowÕs tail. Twenty-four hours later, he developed pain and redness with mild discharge in the right eye. A conjunctivitis was diagnosed and erythromycin ointment (Erythromycin) followed by sulfacetamide-prednisolone sodium phosphate (Vasocidin) ointment were instituted. The eye became progressively more red and painful, and a few days later a Òscleral/episcleral abcessÓ was noted. After surgical drainage of the abcess, the contents were cultured but no organisms were

Fig. 5.31 Right eye of a 67-year-old dairy farmer who was struck in the eye by a cowÕs tail. Note the intense scleritis, with scleral loss inferior to the area of obvious intense inßammation

Fig. 5.32 Scleral biopsy (same patient as in Fig. 5.20): Note the granulomatous inßammation with perivasculitis and collagen necrosis

recovered. Dexamethasone sodium (Decadron) was injected subconjunctivally, and prednisolone acetate (Pred-Forte) and trimethoprim-polymyxin B (Polytrim) drops were begun. The patient was sent to one of us (CSF) because of worsening inßammation. At the time of his Þrst examination by us, visual acuities were 20/400 in the right eye and 20/30 in the left eye. The right eye showed a 4+ injection with necrotizing scleritis all around the globe (Fig. 5.31). The left eye was normal. Review of systems was negative except for the history of trauma, and laboratory tests, including chest and sinus X-rays, and ultrasonography were negative. Excisional scleral biopsy of the affected area was performed as a therapeutic and diagnostic procedure, and specimens were processed for histopathologic studies for culture. A chronic granulomatous inßammation with perivasculitis and collagen necrosis was seen (Fig. 5.32). Giemsa and Gomori methenamine silver stain demonstrated the presence of fungal forms with septate hyphae forming acute angles, a morphology consistent with Aspergillus. Aspergillus fumigatus was later recovered on culture (Fig. 5.33). Flucytosine (1%) and amphotericin B (0.15%) (Fungizone) drops, ßuconazol (Dißucan) tablets, and polymyxin B-bacitracin (Polysporin) ointment were begun. A small inferior retinal detachment was noted in spite of steady but slow improvement in external ocular

Fig. 5.33 Scleral biopsy from a 67-year-old patient with necrotizing scleritis, which developed following trauma to the right eye, inßicted by a cowÕs tail. Scleral biopsy has been stained with Gomori methenamine silver stain. Note the large number of Þlamentous fungi (black) in this scleral biopsy specimen

inßammation. Six months later, the areas of active necrotizing scleritis had vanished, the small inferior retinal detachment had resolved, and the visual acuity was 20/200. Treatment was discontinued without recrudescence of the inßammatory activity.