Scleritis is a painful and potentially sight-threatening disorder. From a strict anatomical viewpoint, scleritis is not a form of uveitis but rather an inflammatory disorder that is similar in pathogenesis to many forms of uveitis. When severe, scleritis is often associated with inflammation in the underlying uveal tissue. Entire books have been written on scleritis, and some of its key features are discussed in this chapter. Like uveitis, scleritis is often associated with underlying systemic disease. Additionally, the therapeutic approaches to scleritis and uveitis share many similarities. In contrast to scleritis, episcleritis is a disorder involving the more superficial episclera and tends to be more acute and less severe than scleritis. Importantly, episcleritis is rarely, if ever, vision threatening and may resolve without therapy. Episcleritis is also discussed in this chapter.
Episcleritis is an inflammatory disorder involving the episcleral tissue that lies superficial to the sclera, just beneath Tenon’s capsule. Although it occurs in both sexes and at all ages, it is seen more frequently in young to middle-aged women. Episcleritis is usually mild, characterized by slight conjunctival injection and the presence of a foreign body sensation. The episodes often resolve without treatment, but can recur. Occasionally patients may experience more severe redness and pain. Inflamed episcleral blood vessels tend to have a salmon color in natural light, radiate from the limbus, and can be moved over the sclera with a cotton-tipped applicator. In addition, these more superficial vessels will blanch after administration of topical phenylephrine. A nodular episcleritis has been described.
In 50% or more of patients episcleritis is idiopathic; however, many of the diseases associated with scleritis have also been associated with episcleritis. In a review of 100 patients with episcleritis, an associated systemic disease was found in 36 (36%). Although often self-limited, episcleritis can be associated with corneal involvement, uveitis, and glaucoma.
Extensive evaluation for underlying disease may not be warranted for mild forms of the disease, especially if it is not recurrent. When treatment is required, the disease often responds to topical or oral nonsteroidal antiinflammatory drugs (NSAIDs) or to topical corticosteroids. Although topical vasoconstrictors can reduce the redness, they should be used sparingly. In patients with episcleritis that fails to respond to initial therapy one should suspect the possibility of a masquerade syndrome, such as a conjunctival malignancy or the presence of an underlying systemic disease.
The differential diagnosis of episcleritis includes conjunctivitis, a conjunctival malignancy such as lymphoma, medications, and scleritis. Conjunctivitis, whether allergic or infectious, can frequently be distinguished from episcleritis based on symptoms and examination. Infectious conjunctivitis is usually associated with a discharge and allergic conjunctivitis with itching and chemosis. Scleritis is anatomically deeper and has a distinct appearance. Malignant conjunctival lesions also tend to have a specific appearance and are rarely mistaken for episcleritis. A number of medications have been associated with both episcleritis and scleritis and are listed in Box 20–1 .
The visual prognosis for patients with episcleritis is usually good. Some patients have a single episode, and in those with recurrent disease the frequency tends to diminish over time. As up to a third of patients can have an associated systemic disease, and because episcleritis can be associated with ocular complications usch as uveitis and glaucoma, patients with more severe or recurrent episcleritis should be carefully assessed and treated. Table 20-1 compares the features of episcleritis and scleritis.
|Anatomy||Episclera (deep to Tenon’s capsule)||Sclera|
|Gender||Predominantly women||Predominantly women|
|Clinical features||Mild pain, transient||Painful|
|Underlying systemic disease||Occasional||Common|
|Treatment||May not be needed||Needed|
The severity of scleritis varies greatly, but the disease can result in loss of vision and be difficult to treat. Scleritis is characterized by eye pain and redness of the sclera and episclera. The pain is usually gradual in onset but can become excruciating, with the feeling of something boring into the eye, and can wake the patient from sleep. The pain may radiate to the forehead or to other parts of the face, and may be associated with photophobia and tearing. Corneal involvement, anterior uveitis, and exudative retinal detachments can occur and cause decreased vision. The inflamed sclera is deep to the episclera, typically with a violaceous hue, and the inflamed vessels cannot be moved with a cotton-tipped applicator ( Fig. 20-1 ). The disease is most common in the fourth to sixth decades of life and more common in women. Scleritis is bilateral in more than 50% of patients, but frequently starts in one eye. It can be divided into anterior and posterior disease ( Table 20-1 ). Anterior scleritis has been classified into four additional categories ( Table 20-2 ): diffuse, nodular, necrotizing with inflammation, and necrotizing without inflammation. Necrotizing scleritis without inflammation is also called scleromalacia perforans.
|Necrotizing scleritis with inflammation||10|
|Necrotizing scleritis without inflammation (scleromalacia perforans)||1–5|
Necrotizing scleritis is a severe form of the disorder, frequently associated with both blinding ocular disease and life-threatening systemic disease. An underlying systemic disease was found in approximately one-half of patients with necrotizing scleritis. Necrotizing scleritis with inflammation is almost always painful. The sclera is edematous, and inflammation leads to scleral thinning, which allows the underlying choroid to become visible. Intraocular inflammation is often seen in severe cases of scleritis. Fluorescein angiography shows hypoperfusion or nonperfusion of the scleral vessels. Other complications of scleritis include cataract and glaucoma.
Posterior scleritis is defined as inflammation of the sclera posterior to the ora serrata. Symptoms of posterior scleritis can be subtle, and the disease is frequently misdiagnosed. As with other forms of scleritis, pain is the most common symptom; however, vision is more frequently affected. Unlike other forms of scleritis, redness can be subtle and missed on examination. Other findings include retinal and or choroidal folds, exudative retinal detachments, or choroidal masses. As with anterior scleritis, masquerade syndromes should be suspected in atypical cases of posterior scleritis, especially when the disease does not respond to treatment. Some of the malignant diseases masquerading as posterior scleritis include lymphoma, metastatic carcinoma, and choroidal melanoma. We have also seen occurrences of benign lymphoid hyperplasia involving the choroid and juvenile xanthogranuloma misdiagnosed as posterior scleritis. Nonmalignant disorders, including retinal detachments and central serous retinopathy, can also masquerade as posterior scleritis.