The commonest presentation of tubercular scleritis is similar to that of other infectious scleritis, with pain, eye redness, and blurring of vision. Patients can complain of severe boring ocular pain, which may be referred to other regions of the head or face. The globe is often tender to touch.

As with other types of scleritis, the sclera may assume a violaceous hue, better seen in natural ambient sunlight. Inflamed episcleral vessels can have a crisscross pattern (in patients with episcleritis). Clinically, the blood vessels are adherent to the sclera and will not be able to be moved with an applicator. Scleral edema can be noted by slit lamp examination. Edges of the scleritis can be more yellowish white as compared to the noninfectious forms, which will be whitish and more avascular (Fig. 13.1).

Tubercular scleritis is usually anterior, with painful nodular lesions with localized slight elevation of the sclera. The lesions can be non-necrotizing or necrotizing (which can result in scleromalacia). The sclera usually appears necrotic, thin, and avascular. Inflammation may be seen at the edges. Scleral perforation can occur if disease is severe. Diffuse scleritis is less common than nodular scleritis in patients with TB [8]. Posterior scleritis resulting from TB is extremely rare, and it may present as an isolated posterior scleritis or posterior scleral tuberculoma [5, 9]. Unilateral optic disc swelling may present secondary to tubercular posterior scleritis [10]. It has also been reported that tubercular scleritis can present with subretinal abscess [11].

Scleritis in TB may be isolated (Fig. 13.1) or can occur together with corneal or iris involvement. This will result in sclerokeratitis and uveitis, respectively. Anterior granulomatous uveitis can occur together with scleritis, and posterior synechiae are often seen [12]. Tuberculous sclerouveitis can rarely masquerade as an ocular tumor and can be associated with necrotizing scleritis [13].

Standard work-up of scleritis should be performed, with a complete physical examination, paying particular attention to the respiratory system, skin, and musculoskeletal system.

Other etiologies of scleritis should also be considered. Baseline laboratory investigations should include a complete blood count (CBC) , erythrocyte sedimentation rate (ESR) , C-reactive protein (CRP) , treponemal serology , tuberculin skin test (refer below), and immune markers such as rheumatoid factor, antinuclear antibodies (ANA) , and anti-neutrophil cytoplasmic antibodies (ANCA) .

Further investigation and work-up should depend on demographics of the patient. If the patient resides in a non-endemic country where the incidence of TB is low, laboratory investigations should be done on a case-by-case basis. A failure of the inflammation to improve on the corticosteroid therapy (topical or systemic) should raise the index of suspicion for infectious scleritis, and tubercular scleritis should be a differential. However, in a TB-endemic country, index of suspicion should be much higher, and laboratory investigations for TB should be considered much earlier on [14].

Tuberculin skin test can be done using the Mantoux method, which is an intradermal injection of 0.1 mL (two tuberculin units) purified protein derivative and the resultant induration after 72 h measured by an independent observer [15]. Interferon-gamma release assays (IRGAs) and polymerase chain reaction (PCR) for detection of TB DNA can also be done if clinically indicated. Chest radiograph should also be obtained to look for any pulmonary manifestation of TB or latent TB.

Cultures of the involved area, including the base and edge of the lesion, can be obtained if there is an indication. Clinicians can consider a lamellar scleral biopsy if clinical suspicion is high or the scleritis worsens with anti-inflammation therapy alone [16].

Usual scleritis management with nonsteroidal anti-inflammatory drugs (NSAIDs ) should still be commenced, if there are no contraindications.

Antituberculosis therapy (ATT) should be initiated upon diagnosis of tubercular scleritis. Typically, a four-drug regimen is started, namely, rifampicin, isoniazid, pyrazinamide, and either ethambutol or streptomycin. The exact treatment regimen and side effects should be comanaged with a physician.