Necrotizing scleritis is the most severe and destructive type of scleral scleritis and is more likely to lead to vision loss. It is more frequently associated with systemic disease (approximately 50%–60%), some being life-threatening systemic vasculitic diseases. Necrotizing scleritis more frequently affects older individuals and is more prevalent in women. In the past, patients with necrotizing scleritis suffered from mortality rates as high as 30%; however, this improved significantly with the evolution of biologic therapies. Necrotizing scleritis can be further subdivided into 2 groups: (1) necrotizing scleritis with inflammation and (2) necrotizing scleritis without (overt) inflammation (scleromalacia perforans).
Necrotizing scleritis with inflammation
Necrotizing scleritis with inflammation is characterized by overt signs and symptoms of scleral inflammation. It may be subdivided into 3 types: (1) vaso-occlusive, (2) granulomatous (Fig 7-5), and (3) postsurgical.
The vaso-occlusive type progressively displays plaques of nonperfusion of episclera/conjunctiva, associated with scleral edema/infiltration and severe congestion of adjacent episcleral/conjunctival vessels (Fig 7-6). The limbal area and peripheral cornea are often spared. These cases are usually associated with infection or with an underlying systemic immune-mediated disease.
The granulomatous type typically starts with necrotizing inflammation of the limbal area, further extending anteriorly to the cornea and posteriorly to the sclera. The inflamed area assumes a “lumpy” aspect, associated with inflammatory infiltration and edema. Subsequently, necrosis and ulceration of the affected tissues (cornea, conjunctiva, episclera, and sclera) develop. This granulomatous type is frequently associated with systemic vasculitides, particularly granulomatosis with polyangiitis and polyarteritis nodosa. It is important to note that other subtypes of necrotizing scleritis may also display granulomatous inflammation on histopathology.
The postsurgical type is rare but frequently arises a few months to several years after surgical trauma to the sclera. It may be infectious or noninfectious. Procedures associated with postsurgical scleritis include cataract, strabismus or retinal surgery, trabeculectomy, cryotherapy, and pterygium excision, the last especially with use of mitomycin C or beta radiation. Recalcitrant inflammation, with progressive necrosis of the sclera, develops commonly at the site of the surgical insult (Fig 7-7), or sometimes more distant to the surgical incision. Many of these patients have an underlying autoimmune disease, with scleral surgical injury being the possible trigger for the local inflammatory process. It is important to exclude infection in these cases.
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Watson PG, Hazleman BL, McCluskey P, Pavésio CE. The Sclera and Systemic Disorders. 3rd ed. London: JP Medical; 2012.
Necrotizing scleritis without (overt) inflammation
Necrotizing scleritis without (overt) inflammation, also called scleromalacia perforans, is characterized by lack of significant symptoms and apparent signs of clinical scleral inflammation. On histopathology, however, there is inflammatory cell infiltration in the sclera. The necrotizing granulomatous response leads to progressive (and “silent”) destruction of the scleral tissue, which may extend circumferentially, eventually leaving a staphyloma. This entity has been historically misnamed scleritis without inflammation. Patients with scleromalacia perforans are often elderly women with long-standing rheumatoid arthritis. They typically present with yellowish or white necrotic scleral plaques involving the sclera and episclera (sequestrum) of both eyes. These plaques are surrounded by mildly dilated episcleral vessels. Associated staphylomata are covered by conjunctiva and a thin translucent layer of fibrous tissue (Fig 7-8). Despite the term “perforans,” these lesions do not usually perforate spontaneously.
Excerpted from BCSC 2020-2021 series: Section 9 - Uveitis and Ocular Inflammation. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.