Fig. 3.32 Immunoßuorescence photomicrograph: conjunctival biopsy, patient with scleritis. Anti-IgG antibody has been used. Note the presence of IgG in the vessel wall, indicating the presence of inßammatory microangiitis (magniÞcation ×28)

nal mass is easily accomplished with MRI. In addition, some orbital tumors causing choroidal folds and retinal striae, also signs of posterior scleritis, can be successfully detected by MRI. MRI does not use ionizing radiation and although intravenous injection of gadolinium is useful, there is often less need to rely on injectable agents to provide soft tissue details. Other advantages of MRI over CT include its ability of visualize planes other than the axial plane with no loss of spatial resolution, its ability to detect areas of demyelinating activity in multiple sclerosis, and its ability to detect microinfarcts in patients with vasculitic diseases (Fig. 3.31). On the other hand, MRI is much more expensive than CT and it is a relatively slow process compared to CT; MRI cannot be performed in the presence of a metallic foreign body because it can harm vital orbital structures; patients with cardiac pacemakers should not be imaged with MRI because of the possibility of pacemaker malfunctions.

3.3Biopsy

The third phase of the approach to scleritis includes the decision as to whether or not a tissue biopsy should be performed. Ocular tissue biopsy may be indicated in some cases of diffuse, nodular, or necrotizing scleritis that may be associated with a systemic vasculitic disease or with a local or systemic infection (see Chap. 5).

3.3.1Biopsy for Suspected Systemic Vasculitic Disease

Episcleral and perforating scleral vessels consist of capillary and postcapillary venules; because capillaries do not have tunica media, a purely classic, histopathological deÞnition of vasculitis cannot be applied to them. The term inflammatory microangiopathy has been adopted by us to deÞne histopathologic neutrophilic inÞltration in and around the vessel wall of capillary and postcapillary venules. Inßammatory microangiopathy may also be deÞned as immunoreactant deposition in the vessel wall, as detected by immunoßuorescence studies (Fig. 3.32).

Detection of inßammatory microangiopathy in conjunctival and/or scleral tissues from patients with recurrent nodular or diffuse scleritis may be helpful in supporting a diagnosis of suspected systemic vasculitic disease. However, because inßammatory microangiopathy in conjunctival and/or scleral tissues is nearly always present in necrotizing scleritis [126], tissue biopsy in these cases is not required.

Conjunctival and/or scleral inßammatory microangiopathy can be associated with inßammation of smalland medium-sized vessels elsewhere in the body as part of systemic vasculitic syndromes. Vasculitis of smalland mediumsized vessels may appear in skin or other involved organs in patients with rheumatoid arthritis, SLE, relapsing polychondritis, arthritis associated with inßammatory bowel disease, psoriatic arthritis, polyarteritis nodosa, Beh•etÕs disease, CoganÕs syndrome, granulomatosis with polyangiitis (Wegener), and allergic granulomatous angiitis (ChurgÐStrauss syndrome). Although in ankylosing spondylitis, reactive arthritis, and giant-cell arteritis the presence of vasculitis is mostly found in large-sized vessels, smalland medium-sized vessels also may be affected.

The presence of inßammatory microangiopathy in conjunctival and/or scleral tissue can be helpful in making the decision to institute immunosuppressive therapy. In patients with systemic vasculitic disease and recurrent nodular or diffuse scleritis, the demonstration of inßammatory microangiopathy in conjunctival and/or scleral tissue implies ocular involvement of the