Ординатура / Офтальмология / Английские материалы / Ocular Disease Mechanisms and Management_Levin, Albert_2010

sarcoidosis, if present, might help in the diagnosis. In the absence of such manifestations, the characteristic findings of SO seen in FA and ultrasound scan would help differentiate these two entities.

Both posterior scleritis and SO may present with exudative retinal detachment and disc edema. However, SO is typically a bilateral disease, whereas posterior scleritis most commonly presents as a unilateral inflammation. Although ultrasound scans may reveal diffuse choroidal thickening and exudative retinal detachment in both of these entities, choroidal thickening in posterior scleritis shows high internal reflectivity with evidence of retrobulbar edema.

Treatment

The successful control of inflammation in patients with SO depends on early and aggressive treatment with large doses of corticosteroids until the inflammation is resolved. Before the use of corticosteroids, the prognosis for SO was con­ sidered very poor. Makley and Azar reported in 1978 that patients treated with corticosteroids had a favorable visual outcome, with 64% attaining a final visual acuity of 20/60 or better.17 Lubin et al in 1980 supported these data and demonstrated that corticosteroid therapy changed both the character and the severity of the inflammatory process.10 In 1983, Reynard et al stated that corticosteroid therapy prevented severe visual loss.18

Some patients may be refractory to corticosteroid therapy or may experience unacceptable side-effects during treatment. Such patients have been shown to benefit from ster- oid-sparing immunosuppressive drug therapy, including methotrexate, cyclophosphamide, ciclosporin A, chlorambucil, and mycophenolate mofetil. Enucleation of the injured globe within 2 weeks of penetrating trauma is generally believed to prevent the development of SO. But with the advances in surgical techniques, many eyes once considered nonviable may have a fair prognosis and the injured eye might eventually have the better vision. Hence, the decision to perform primary enucleation should be made cautiously. Enucleation should be considered in those cases where the traumatized eye has no light perception, has a total afferent pupillary defect, and is severely disorganized, making it impossible to repair surgically. In such situations it is important to discuss with the patient the possibility of developing SO in the nontraumatized eye, and enucleation should be carried out within 2 weeks of trauma.

The advantage of enucleating the exciting eye once the disease has started in the sympathizing eye is a controversial issue. Review of the literature shows conflicting results with regard to the benefits of enucleation after the onset of inflammation. It is therefore important to try saving the injured eye, especially if any potential for useful vision exists in the exciting eye.

Prognosis and prevention

Before the use of corticosteroids, the visual prognosis of SO was generally considered to be poor. The aggressive use of corticosteroids in combination with immunosuppressive therapy has improved the visual prognosis. However, the

Pathology

relapsing nature of the disease demands careful long-term follow-up to prevent serious complications associated with recurrences.

It is interesting to analyze a few studies which stated prognostic factors based on histopathological findings. Lubin et al reported a direct correlation between the severity of inflammation in the exciting eye and the final visual acuity of the sympathizing eye.10 However, Winter19 and Reynard et al18 observed no direct correlation.

Makley and Azar17 reported on the long-term follow-up of patients with SO in 1978. In their series, they observed that relapses and complications such as secondary glaucoma, cataract, exudative retinal detachment, and choroidal scarring were common among patients with SO. Many patients treated with steroids retained a favorable visual acuity. The duration of such corticosteroid therapy was variable and ranged from a few months to 6 years.

The only suggested prevention for SO is early enucleation of the injured globe. In 2006, Su and Chee stated that industrial safety laws that mandate the use of personal protective equipment while working would reduce the incidence of work-related trauma and help reduce the incidence of SO.9 Advances in surgical techniques have enabled ophthalmologists to operate successfully on severely traumatized eyes and achieve good wound closure of penetrating eye injuries. This would, in turn, prevent the escape of uveal antigen to the regional lymphatic system, thereby reducing the incidence of SO. It is also important to remember the association of SO with intraocular surgical procedures, especially in patients with a previous history of penetrating trauma or repeated surgery. Such patients should be closely monitored, and appropriate levels of anti-inflammatory drug therapy should be introduced with any early evidence of inflammation.

Pathology

SO has a broad histolopathologic presentation. The classic description represents a diffuse nonnecrotizing granulomatous inflammation made up of lymphocytic infiltration of the choroid with nests of epitheliod cells and a few multinucleated giant cells (Figure 81.1). These epithelioid and giant cells often contain melanin pigment. Similar inflammatory infiltrate could be seen in the iris, ciliary body, and pars plana region. Absence of necrosis is a characteristic feature. The retina and choriocapillaris are not usually involved in the inflammatory process.

The cytologic composition of the infiltrating cells was demonstrated by immunohistochemistry. Jakobiec et al reported that the choroidal infiltration was predominantly T lymphocytes of cytotoxic subset.20 They demonstrated that the epithelioid cells and phagocytic cells in the choroid harbor antigenic determinants specific to cells originating from the reticuloendothelial system. However, the identity and origin of these epithelioid cells have not been clearly elucidated.20 Chan et al in 1985 found that the predominant T-cell subtype within the choroid was the helper variety.21 The specimen used for this analysis was obtained at a relatively earlier stage in the disease process than the one studied by Jakobiec et al. Hence it was postulated that T-helper cells predominate at an earlier stage of the disease and T-cytotoxic cells at the latter part of the disease process. Plasma cells

were believed to represent an altered cellular infiltrate in the uvea due to corticosteroid therapy. Eosinophils were thought to infiltrate at an early stage in the disease process.10

Nodular clusters, referred to as Dalen–Fuchs nodules, were often seen lying between the RPE and Bruch’s membrane. These nodules were made up of focal collections of epithelioid cells, modified RPE cells, and lymphocytes. Jakobiec et al believed that these epithelioid cells were similar in origin to the choroidal infiltrate and were derived from bone marrow monocytes.20 In contrast, a few reports suggested that the epithelioid cells of the Dalen–Fuchs nodules could be altered RPE cells.22,23

The small depigmented lesions seen in the peripheral fundus in chronic VKH and SO patients clinically were thought to represent Dalen–Fuchs nodules. But Inomata and Rao reported that these lesions represented the focal disappearance of RPE cells and the presence of chorioretinal adhesions; they found no histologic confirmation that these were Dalen–Fuchs nodules.24

Croxatto et al described atypical histopathologic features of SO.25 They showed that choriocapillaris was focally involved rather frequently (40%) and that retinal perivasculitis was seen in many patients (50%). These findings were associated with severe choroidal inflammation.

The sclera could be involved, with infiltration especially around the emissary veins, and there could be a granulomatous process extending from the juxtapapillary choroid into the optic nerve and surrounding meningeal sheaths.4,10,24

Many studies have described an association between the degree of pigmentation and the intensity of uveal inflammation in SO. Marak and Ikui reported in 1980 that the severity of inflammation and the proportion of epithelioid cell response in the choroid were related to the degree of pigmentation. Hence, they stated, choroidal thickening was more marked in eyes removed from heavily pigmented patients than in those removed from white patients.26

Etiology

Although a penetrating wound appears to be a predisposing and required condition for the development of SO, not all patients who have an ocular injury develop SO. This suggests a possible genetic predisposition to the development of SO.

Genetic risk factors

There may be a possible genetic predisposition to the development of SO. Human leukocyte antigen (HLA) types reported in SO include HLA-11,4 HLA-DR4/DRw53, HLA-DR4/DQw3,27 HLA-DRB1*O4, -DQA1*03, and -DQB1*04.14 In addition, the HLA-DRB1*04-DQA1*3 haplotype is a marker of a more severe clinical phenotype in SO, with increased disease susceptibility in British and Irish patients.28 Recent evidence has shown that cytokine gene polymorphisms are markers for disease severity in SO.29 Polymorphisms that result in the upregulation of proinflammatory cytokines are predicted to create a proinflammatory environment in the eye and worsen the severity of inflammation. These markers were also associated with disease recurrence. Analyzing cytokine gene polymorphism before starting treatment with biological agents (e.g., antitumor

Etiology

necrosis factor drugs) might help us to identify patients who will benefit most from such therapies.

Other risk factors

The most important risk factor for the development of SO is a history of penetrating ocular injury. An overwhelming number of SO patients show evidence of such an injury in the exciting eye.

The importance of penetrating ocular trauma in the pathogenesis of SO was explained by Rao et al, who demonstrated that bilateral panuveitis developed after a sub­ conjunctival injection of retinal antigen in one eye.30 They postulated that the penetrating injury exposed the regional lymphatics to intraocular antigens, initiating an immune reaction.

SO following nonpenetrating injury is rare. Only a few cases of SO following cyclocryotherapy and Nd:YAG cyclotherapy without prior history of trauma or surgery have been reported. Nonetheless, one should always be careful in recommending such therapy for patients with glaucoma, especially if there is a past history of surgery or trauma. It is also important to monitor patients after cyclodestructive procedures to detect early evidence of SO. It is advisable to titrate carefully the amount of Nd:YAG cyclotherapy to prevent excessive treatment.

Although rare, there have been case reports of SO following diode laser cyclophotocoagulation,9 ruthenium plaque brachytherapy,31 and irradiation for ocular melanoma.32 However, a microperforation of the globe in such cases cannot be excluded completely.

In contrast to previous literature, recent incidence data showed an increase in SO following surgical procedures.6,9 Advances in surgical training and surgical instrumentation have enabled ophthalmologists to operate on complicated, severely damaged eyes that, in the past, would have been enucleated. These developments could conceivably contribute to the recent increasing trend of ocular surgery being an important cause of SO. Many surgical procedures have been associated with SO. Examples include cataract surgery, glaucoma filtering procedure, and retinal surgery evisceration.

The role of vitrectomy in inducing SO is still unclear. While several cases have been reported, the majority of these cases had a history of either penetrating trauma or repeated surgical procedure in the past. In 1982, Gass7 reported a 0.06% incidence of SO after vitrectomy and stated that, if vitrectomy was considered as the only surgical procedure causing a penetrating wound, the incidence would be 0.01%. Kilmartin et al, in 2000,33 stated that there is a significant risk of developing SO following vitrectomy and stressed the importance of counseling patients about this possibility before performing vitrectomy. It was postulated that the breakdown of the blood–retinal barrier and the subclinical incarceration of uveal tissue at the wound site could contribute to the development of SO. These uveal tissue antigens can also be released during cryoretinopexy and subretinal fluid drainage. The development of signs of uveitis in the opposite eye after vitrectomy, especially in patients with repeated surgeries, should alert the surgeon to the possibility of SO.

It is thought that removal of the exciting eye by enucleation rather than by evisceration is a safer procedure, because

evisceration is believed to leave behind uveal tissue that could cause an immune response leading to SO. However, there is a general consensus that prosthetic motility and long-term socket stability are better in patients who undergo evisceration rather than enucleation. The scleral shell is also thought to provide a barrier for orbital spread of infection. In contrast to these advantages it is reported that evisceration could cause possible dissemination of an unsuspected tumor or can lead to inadequate volume if the eye is phthisical.

Although cases of SO following evisceration have been reported, the majority of these eyes had a history of previous trauma or surgical procedure. Therefore, it is unclear whether the initial injury or surgery was responsible for the occurrence of SO.34–37 SO has a very low incidence and a large number of cases would need to be studied to arrive at a conclusive statistical proof of the association between evisceration and SO.

Pathophysiology

Several studies have proposed a T-cell-mediated autoimmune reaction to antigenic protein from the uvea–retina as the pathogenic mechanism for the development of SO.20,21,24,38 Wong et al reported enhanced transformation of peripheral lymphocytes from patients with SO exposed to uveal–retinal extracts in tissue culture, suggesting that these patients have lymphocytes that are sensitized to components of uveal–retinal antigen.39 Various ocular antigens such as uveal melanin, uveal melanocytes, RPE, and retinal S-anti- gen have been implicated in the pathogenesis of SO in the past. In the animal model of uveitis, Rao et al showed that guinea pigs injected with retinal S-antigen developed an ocular inflammatory reaction similar to that of SO, including granulomatous panuveitis and focal collections of inflammatory cells at the level of RPE similar to Dalen– Fuchs nodules.40 Furthermore, experimental observations noted that intraocular injection with retinal S-antigen produced a mild inflammation in the injected eye, with no sympathetic inflammation in the fellow eye. In contrast, subconjunctival injection produced a marked intraocular inflammation in both the injected eye and the fellow eye.30 These observations could be explained by the phenomenon of “immune privilege.” This phenomenon is believed to be due to features such as the presence of a tight blood–ocular barrier, lack of intraocular lymphatic system, and an intraocular microenvironment that is immunosuppressive. Hence, antigens experimentally placed in the eye would fail to reach the lymphatic system directly and would first encounter immunologic surveillance in the spleen via the blood stream. This, in turn, would fail to produce an immunopathologic response in the host. In contrast, subconjunctival injection of the retinal S-antigen would provide antigen access to the regional lymph nodes via the conjunctival lymphatics, leading to an immunopathologic reaction in the form of bilateral intraocular inflammation.

It is hypothesized that ocular trauma would cause an enhanced release of sequestered self antigens, which would stimulate the local antigen-presenting cells (APC). These, in turn, would carry the antigen to draining lymph nodes via the conjunctival lymphatics, where T-cell activation would then take place. Once activated, T cells would enter the eye

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tissue and be exposed to target antigens leading to the initiation of an inflammatory process.

The possibility of a cell-mediated immune reaction in the pathogenesis of SO has been supported by many immunohistochemical studies. SO includes a cellular infiltrate of predominantly T lymphocytes in the choroid. Immunohistochemical studies have demonstrated that these cells predominantly exhibit markers of CD4 (helper) variety. The CD4-positive T cells respond to peptides (antigens) when presented with major histocompatibility complex (MHC) class II molecules (HLA complex). These molecules are expressed by the bone marrow-derived APC cells within the uvea. Antigens are processed by these cells via a complex intracellular system and then bound to HLA molecules on the surface of APC.

Polymorphism in the HLA genes is believed to influence the initial presentation of disease-inducing peptides (antigens) to the T cells through their effect on HLA peptides, binding affinity. These strong binding sites form a stable complex with antigens and influence the selection and activation of T cells, thereby leading to disease susceptibility.

Various ocular antigens, have been hypothesized to be involved in the pathogenesis of SO. Yamaki et al,41 in 2000, demonstrated that lymphocytes from patients with VKH disease were reactive to peptides derived from tyrosinase family proteins and that pigmented rats immunized with these peptides developed a disease similar to human VKH disease. Tyrosinase family proteins are enzymes needed for melanin formation and are expressed on melanocytes. It was suggested that SO, which resembles VKH clinically as well as histopathologically, was an autoimmune process against tyrosinase family protein. Furthermore these peptides were reported to contain HLADRB1*0405 binding sites, which are associated with antigen presentation to T lymphocytes in patients with SO. Once the T cells recognize these surface antigens, they trigger the inflammatory process by releasing cytokines that initiate a sequence of events leading to the recruitment of additional inflammatory cells to the site of inflammation. Finally, all of these activated inflammatory cells would cause tissue damage by releasing various secretory products, such as proteases and free radicals (Figure 81.2).

Studies have investigated the role of RPE in the downregulation of inflammation.42,43 These cells were believed to synthesize and release a protein called “retinal pigment epithelial protective protein” that provides protection against extracellular superoxide formation in uveitis. These findings could explain the constant histopathological feature observed in SO, wherein the choriocapillaris layer and the retina are preserved despite extensive uveal infiltration by inflammatory cells. But it should be noted that severe choroidal inflammation could cause disruption of the RPE and allow T lymphocytes to migrate into the retina, leading to retinal autoimmunity caused by altered tolerance to the retinal protein(s). In 2002 Wang et al reported a case of progressive subretinal fibrosis with multifocal granulomatous chorio­ retinitis after intraocular surgery and proposed that this was a variant of SO based on histopathologic and immunohistochemical findings. Furthermore, Wang et al demonstrated the presence of antibodies directed against retinal photoreceptors and pigment epithelium. Based on their findings,

they postulated that altered tolerance to retinal protein played a role in the pathogenesis of SO.44

Summary

SO is a T-cell-mediated autoimmune disease that is directed against antigenic peptides of the uveal melanocytes or retina or RPE. Clinical history of penetrating ocular injury with

subsequent development of bilateral intraocular inflammation is a distinguishing feature of this entity. It is essential to begin aggressive treatment promptly with corticosteroids, and if necessary, to introduce immunomodulatory therapy once the possibility of infection and malignancy is carefully ruled out. As relapses are common, these patients should have long-term follow-ups to prevent the development of complications associated with chronic intraocular inflammation.

4.Marak GE Jr. Recent advances in sympathetic ophthalmia. Surv Ophthalmol 1979;24:141–156.

6.Kilmartin DJ, Dick AD, Forrester JV. Prospective surveillance of sympathetic ophthalmia in the UK and Republic of Ireland. Br J Ophthalmol 2000;84:259– 263.

10.Lubin JR, Albert DM, Weinstein M. Sixty-five years of sympathetic ophthalmia. A clinicopathologic review of 105 cases (1913–1978). Ophthalmology 1980;87:109–121.

13.Easom H, Zimmerman LE. Sympathetic ophthalmia and bilateral phacoanaphylaxis. A clinicopathologic correlation of the sympathogenic and

sympathizing eyes. Arch Ophthalmol 1964;72:9–15.

16.Rao NA, Marak GE. Sympathetic ophthalmia simulating Vogt–Koyanagi– Harada’s disease: a clinico-pathologic study of four cases. Jpn J Ophthalmol 1983;27:506–511.

19.Winter FC. Sympathetic uveitis; a clinical and pathologic study of visual result. Am J Ophthalmol 1955;39:340–347.

25.Croxatto JO, Rao NA, McLean IW, et al. Atypical histopathologic features in sympathetic ophthalmia. A study of a hundred cases. Int Ophthalmol 1982;4:129–135.

30.Rao NA, Robin J, Hartmann D, et al. The role of the penetrating wound in the

development of sympathetic ophthalmia: experimental observations. Arch Ophthalmol 1983;101:102–104.

36.Levine MR, Pou CR, Lash RH. The 1998 Wendell Hughes lecture. Evisceration: is sympathetic ophthalmia a concern in the new millennium? Ophthalm Plast Reconstr Surg 1999;15:4–8.

44.Wang RC, Zamir E, Dugel PU, et al. Progressive subretinal fibrosis and blindness associated with multifocal granulomatous chorioretinitis:a variant of sympathetic ophthalmia. Ophthalmology 2002;22:109–111.

Introduction

Scleritis is a rare inflammatory disease which affects the sclera and its adjacent structures such as the episclera, uvea, and cornea. Scleritis can cause severe, disabling pain, destruction of scleral tissue, and the risk of significant visual loss.

The pathophysiology of scleritis is complex, incompletely understood, and complicated by the heterogeneity of the disease as well as the dearth of studies into the immunopathology.

Clinical background

Classification of scleritis

Scleritis may be classified anatomically and by histopathology. The most widely accepted method of classification of scleritis is that described by Watson et al in the 1960s (Table 82.1).1

Historical development and demographic data

Scleritis was described in 1702.2 An early description of scleritis distinguishing it from episcleritis was made in 1830, as reported by Watson and Hayreh in 1976.3 The prevalence of scleritis has been estimated at 8 cases in 100 000 and the incidence at 1.3 cases per 100 000 person-years.4 There are no described racial or geographic differences. Females are affected slightly more frequently by scleritis (1.6 : 1).5,6 It can affect any age but is rarely observed in children. The mean age of onset of scleritis is 45–60 years.

Clinical features of scleritis

Key ocular signs and symptoms

•  Pain in scleritis is the main symptom. It can be severe, gnawing, or boring in nature and can affect sleep.

•  Scleritis is often painless in chronic rheumatoid arthritis when the presentation is scleromalacia perforans,

Scleritis

Srilakshmi M Sharma and James T Rosenbaum

which is an extra-articular manifestation of rheumatoid arthritis.

•  Redness of the sclera due to dilation and hypervascularity of scleral and episcleral vessels gives the eye a bloodshot appearance (Figure 82.1). Redness of the sclera may be:

  Localized to one or more sectors of the sclera  Diffuse.

•  Scleral thinning and reorganization of scleral collagen fibrils cause translucency of the sclera and a bluish appearance (Figure 82.1).

•  Posterior scleritis is typically painful at rest and on eye movement. Redness may not be visible. Occasionally posterior scleritis may be painless.

•  Risk factors for an underlying systemic disease include bilateral disease, necrotizing scleritis, scleromalacia perforans, a positive rheumatoid

factor, or antineutrophil cytoplasmic antibody (ANCA) test.7

•  An episodic nature of disease may suggest a diagnosis such as relapsing polychondritis or inflammatory bowel disease.

•  Corneal changes may also occur in scleritis, causing a sclerokeratitis.

•  Scleritis may accompany other ocular signs such as an orbital inflammatory mass in Wegener’s granulomatosis.

Diagnostic workup

Nearly 50% of patients with scleritis have an underlying systemic disease identifiable on medical examination (Box 82.1).8 The systemic associations with scleritis are summarized in Table 82.2 along with appropriate tests for each condition.

Tests and investigations in scleritis

Making a diagnosis of scleritis is usually done on clinical grounds, with the exception of the B scan in posterior

scleritis (Figure 82.2). There are a few tests that would be recommended as screening tests for all patients without an estab­lished cause (Table 82.2). Other tests should be guided by systemic symptoms,­ clinical course, and/or exposure to infective agents.

In general, the typical panel of blood tests that all patients with scleritis should have is summarized in Table 82.3. A recent study has proposed that a rheumatoid factor should also be obtained as a screening test.7

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Significance of antineutrophil cytoplasmic antibodies

Antineutrophil antibodies (ANCA) are used as clinical markers of disease for a number of vasculitides. The most relevant disease associations in the context of scleritis are Wegener’s granulomatosis, polyarteritis nodosa, microscopic polyarteritis, and Churg–Strauss syndrome (Box 82.2). ANCA is the recommended screening test as:

Comments

If this is positive, this may indicate presence of a vasculitis, indicating further workup and medical consultation

A positive test may indicate untreated syphilis, previously treated syphilis, or a false-positive result

•  A positive ANCA may be the presenting symptom of a systemic vasculitis.9,10

•  In a proportion of cases who present with apparently idiopathic scleritis, a positive ANCA may predict development of Wegener’s disease in some patients.7

Box 82.1

Box 82.2

Perinuclear-staining ANCA (pANCA) tends to be linked with renal vasculitis and microscopic polyarteritis. Cytoplas- mic-staining ANCA (cANCA) positivity is highly associated with Wegener’s granulomatosis.11 Sensitivity is 67% for patients with active systemic disease and specificity is 96%.12 There is sometimes clinical overlap in phenotypes of cANCA and pANCA systemic vasculitis; therefore the pANCA may be positive in a Wegener’s-like vasculitic picture.

Role of rheumatoid factor testing

In the general population (without rheumatoid arthritis) the prevalence of rheumatoid factor is around 15%. However, it

has been suggested that, even in the absence of joint symptoms, a positive rheumatoid factor is an independent risk factor for developing rheumatoid arthritis.7 Anticitrullinated peptides are highly specific for RA. Their role in evaluating scleritis has not been studied.

Antinuclear antibodies (ANA) should be tested if scleritis secondary to systemic lupus erythematosus is in the differential diagnosis.13 In the general population 30% of females are ANA-positive so a positive ANA is not diagnostic of this condition.

Differential diagnosis

The most common differential diagnosis is episcleritis (Tables 82.4 and 82.5, Box 82.3).

Other differentials of scleritis

•  Conjunctivitis

•  Keratoconjunctivitis sicca

•  Anterior uveitis

•  Vascular abnormalities of the conjunctiva, e.g., hemangioma

•  Malignant infiltration, e.g., lymphomatous or leukemic14

•  Scleral hyaline plaque: these can be confused with scleromalacia perforans. These are small translucent wedge or circular-shaped areas of sclera. The sclera at the center of the lesions is thin and the underlying uvea is visible through it. It is sometimes seen with calcification. These lesions occur mostly in the population over 60. The plaque can be bilateral and requires no treatment

•  Anterior scleral staphyloma (Figure 82.3).

This unusual condition can be due to progressive myopia, severe chronic glaucoma, or rarely in children after a trabeculectomy. The appearance is similar to that of scleromalacia

perforans. In chronic glaucoma the pressure has to be chronically and significantly raised to cause this appearance.

Treatment of scleritis

Usually active disease requires therapy. Deciding whether scleritis is active is usually according to the degree of pain,

Figure 82.2  B-scan ultrasound of posterior scleritis showing thickening of posterior sclera and the T-sign reflecting edema along the optic nerve and within the subtenon space. (Reproduced with permission from Watson P et al (eds) Sclera and Systemic Disorders, 2nd edn. Butterworth and

Heinemann, 2004.)

difficulty on eye movement, redness, and presence of necrosis. Optic nerve swelling, serous detachments, or demonstration of sclera thickening and edema on B-mode ultrasonography are all features of active posterior scleritis.

About 25% of cases with scleritis overall will require immunosuppressive therapy but the proportion is 70% or more in those with necrotizing disease.

Selection of a particular drug may depend on knowledge of how the underlying disease responds and is tailored to knowledge of the patient’s medical and social history.

Box 82.3  Episcleritis

Table 82.5  Differentiation between episcleritis and scleritis