Uveitis
Delayed-onset postoperative inflammation can result from a diverse range of factors, such as blebitis, bleb-related endophthalmitis, underlying uveitis, mitomycin-C mediated inflammation, herpes infection, phaco-anaphylactic and phacogenic uveitis, intraocular lens (IOL) chafing of the iris, and sympathetic ophthalmia. Delayed postoperative uveitis is defined as inflammation occurring 6 weeks or later postoperatively and is a rare condition that may occur following a glaucoma filtering procedure. Currently, there are very few documented cases of this condition. Even though it is rare, it is important to differentiate the infectious sources of delayed-onset postoperative uveitis after glaucoma filtering surgery from those that are noninfectious so that the appropriate treatment is administered. Infectious cases of uveitis should be considered first. The most common form of late-onset postoperative uveitis after a filtering procedure is blebitis . Brown and colleagues were the first to use the term “blebitis” to describe a limited infection centered around a bleb with or without anterior chamber reaction and no vitreous involvement. In contrast, on the other end of the spectrum, is bleb-related endophthalmitis , which is characterized by a more fulminant course with anterior chamber reaction and the presence of vitritis. Blebitis and bleb-related endophthalmitis typically manifest several months to years after the surgery. Blebitis may often be a precursor to bleb-related endophthalmitis, and early recognition of late-onset bleb-related infections should be taken seriously and promptly treated to avoid severe ocular and visual sequelae. Both forms of bleb-related infection can be differentiated by the extent of ocular inflammation. Patients with blebitis typically complain of redness, foreign body sensation, pain, photophobia, and conjunctival discharge. The conjunctiva around the bleb is also significantly injected. Additionally, the bleb itself usually has a whitish or chalky appearance with or without an epithelial defect. The anterior chamber may have variable degrees of reaction, and a hypopyon may be present in the anterior chamber as well as in the bleb itself. Conversely, patients with bleb-related endophthalmitis typically present with a more fulminant course, which includes rapidly deteriorating vision, redness, pain, and diffuse conjunctival injection. Vitritis, while absent in blebitis, is present in bleb-related endophthalmitis.