EyeWorld Asia-Pacific December 2011 Issue

34 December 2011 EW UVEITIS An update for general ophthalmologists T he Singapore National Eye Centre (SNEC) conducted an update on uveitis for general ophthalmologists on 18 August 2011. The update consisted of seven talks conducted by the clinical staff of SNEC’s Ocular Inflammation and Immunology Service, and focused on clinical clues general ophthalmologists can use to arrive at the correct diagnosis before referring to a uveitis and ocular inflammation specialist. Keratic precipitates: ‘basic signs’ Chee Soon Phaik, MD, head and senior consultant of the serv- ice, kicked off by “going back to basics”: taking a close look at the details of keratic precipitates. Keratic precipitates, she said, are aggregates of inflammatory cells on the corneal endothelium. These aggregates may consist of polymorphonuclear cells, lymphocytes, or epithelioid cells from the aqueous humor. They can be granulomatous or non- granulomatous, and may vary throughout the course of disease. Taking a retrospective look at the case notes of patients referred to her for conditions associated with the appearance of what she called a “basic sign” of ocular inflammation, Prof. Chee noticed that general ophthalmologists tended not to describe the keratic precipitates in their patients. They should, she said; these details can guide a clinician to the correct diagnosis even before or in lieu of special tests such as polymerase chain reaction (PCR) studies—tests that aren’t always accessible or available. Some features to note include the size (small, medium, large), shape (round, filliform, stellate), distribution (including location, clustering, and evenness), color (pigmented, nonpigmented, possibly indicating old or fresh precipitates), and pattern (rings, lines, etc.). However, simple visual examination, even a close one, isn’t always enough, and in such cases in vivo confocal microscopy (IVCM) can be very revealing. Under IVCM, grossly undifferentiated clumps of keratic precipitates can, for instance, be clearly seen as being globular, infiltrative, dendritiform, smooth- rounded, cruciform or stippled. Finer precipitates, said Prof. Chee, are more typical of infections, although stippling tends rather to indicate an immune-mediated condition, while dendritiform precipitates are common in Fuchs’ uveitis syndrome and, to a lesser extent, intermediate uveitis. Infiltrative and dendritiform precipitates are of particular significance, she added; these precipitates indicate either infective or otherwise infiltrative (e.g., tumorous) etiologies. In describing these precipitates, Prof. Chee hinted at what would emerge as a recurring theme for uveitis management: the importance of distinguishing infectious from noninfectious etiologies. Scleritis vs. episcleritis Scleritis and episcleritis are two inflammatory conditions that differ significantly in prognosis and management; it is therefore vital for clinicians to make the distinction early to begin effective treatment, said Anita Chan, MD, a consultant of the service. Episcleritis is inflammation localized to the episclera and Tenon’s layer; it creates an uncomfortable, burning sensation in the affected eye; pain generally occurs later. The condition, she said, tends to be self-limiting but recurrent. Scleritis, on the other hand, is associated with “severe, boring pain”, sometimes radiating to the head and/or jaw; it is progressive and also recurrent, but most importantly is potentially blinding—early effective treatment reduces recurrence and the risk for blindness. About 57% of scleritis cases, said Dr. Chan, are associated with and may in fact be the first manifestation of systemic disease. Beyond the patient’s presentation, she said, a medical history can be helpful, but patients aren’t often able to provide the kind of information needed to make the diagnosis, so a close clinical examination under good lighting is indispensable. With enough lighting, clinicians should be able to differentiate between the pink-red appearance of the more superficial episcleritis and the purplish-bluish hue of the deeper scleritis. There will be no sclera or corneal involvement in episcleritis, while the scleral inflammation and corneal involvement will lead to tenderness on palpation in cases of scleritis. Patients with scleritis may also have cells in the anterior chamber, disc edema, viritis, and exudative retinal detachment. Clinicians should be able to note scleral and vascular changes from previous episodes in recurrences. Some helpful adjuncts to the clinical examination are red- free light (which brings out the Back to basics in uveitis by Chiles Aedam R. Samaniego EyeWorld Asia-Pacific Senior Staff Writer vasculature and reveals the depth of involvement) and the slit beam (the posterior slit beam is displaced in scleritis). Phenylephrine 10% or 2.5% can also be helpful if the inflammation makes it difficult to assess the depth of involvement, said Dr. Chan. Infectious vs. noninfectious hypopyon Hypopyon is basically “pus in the anterior chamber of the eye”, said Lim Wee Kiak, MD, visiting consultant, SNEC. It isn’t very common: Dr. Kiak said that while hypopyon is found in about 35% of Behcet’s cases, it is only seen in about 0.8% (increasing to 2.8% on follow-up) of all uveitis cases—“Rare on rare equals even rarer,” he said. It is, however, a “very significant sign”, pointing to serious pathologies with etiologies that may be infectious or noninfectious. Infectious causes, he said, are associated with a triad of pain, blurring of vision, and redness, and result in unilateral hypopyon more often than not. They are associated with signs such as corneal ulcers, lid swelling and cellulitis—particularly prominent in comparison with noninfectious causes—and the presence of foreign bodies. Treatment in these cases will depend on the causative organism, and associated conditions can include systemic infections such as tuberculosis or Hansen’s disease, syphilis, leptospirosis, and brucellosis. On the other hand, noninfectious hypopyon is more common in HLA B27-positive individuals, and is seen in Behcet’s disease, sarcoidosis, relapsing polychondritis, acute angle closure Assoc. Prof. Chee Soon Phaik, MD Anita Chan, MD Lim Wee Kiak, MD