Causative organisms for blebitis: Staphylococcus epidermidis (more common) and Staphylococcus aureus are the commonest organisms to cause blebitis.

Causative organisms for bleb–related endophthalmitis (BRE): The most common causative organism associated with early-onset BRE is Staphylococcus epidermidis similar to that of acute endophthalmitis after cataract surgery. In contrast, the most common organisms causing late-onset endophthalmitis belong to Streptococcus species and Haemophilus influenzae.

Ramakrishnan et al. [27] reported early-onset blebitis (less than 36 months after trabeculectomy) to be associated with Streptococcus infection. These eyes had severe ocular surface disease and were associated with nasolacrimal duct obstruction.

The causative organism was coagulase-positive staphylococci in eyes with thin cystic bleb and blebitis; coagulase-negative staphylococci were associated with blebitis when there was associated bleb leak. Corynebacterium was isolated when blebitis was associated with blepharitis and Streptococcus was associated with releasable sutures [27]. Ohtomo et al. reported that BRE with highly pathogenic bacteria (Streptococcus species, Enterococcus faecalis, Pseudomonas aeruginosa, and Haemophilus influenzae) was associated with severe visual loss and carried poor prognosis even when intervened within 24 h [19].

Typically the patients of blebitis and BRE report sudden onset of redness followed by pain in the eye, photophobia, discharge, and decreased vision. Many of these patients have prodromal symptoms like brow ache, headache, or external eye infections. The prodrome is longer in blebitis; it is accelerated in endophthalmitis with rapidly worsening ocular pain, reduced visual acuity, and redness within a few hours.

On clinical examination the area of the bleb is congested; there is loss of translucency of the bleb wall with milky content replacing the clear bleb and associated with mild to moderate anterior chamber reaction (Fig. 8.1a). Additionally, anterior chamber inflammation with hypopyon and vitritis may be noted in bleb-related endophthalmitis. (Fig. 8.2a). Ultrasound B-scan may be needed to evaluate the extent of posterior segment involvement.

Management: It is very important to examine these patients as soon as possible probably within an hour [20]. A thorough clinical examination including dilated fundus examination is mandatory to rule out endophthalmitis. One must also rule out blepharitis, nasolacrimal duct obstruction, and other risk factors. Workup must include conjunctival swabs under aseptic precautions, anterior chamber tap, and vitreous biopsy for microbiology investigation. Frequent instillation of appropriate antimicrobial therapy is the management of choice. Treatment could be with broad-spectrum antibiotics with activity preferably against gram-positive organisms. In addition to the spectrum of microorganism coverage, other considerations in choosing the most appropriate antibiotics include better kill kinetics and higher intraocular penetration of the topical antibiotics.

Fourth-generation fluoroquinolones such as moxifloxacin 0.5% or gatifloxacin 0.5% have broad-spectrum coverage and have better intraocular penetration and are widely used in the treatment of blebitis. In cases with severe blebitis, broad-spectrum fortified antibiotic combinations such as fortified cefazolin 5.0% and fortified gentamicin 1.4% are useful. At the initiation of treatment, the frequency of topical antibiotics should be every half to 1 h so as to attain adequate therapeutic concentration of the drug. To ensure close monitoring of compliance and response to therapy, admission and intensive medical care may be required. Subconjunctival injection of antibiotics or systemic therapy is not recommended unless the condition is severe and/or the compliance to topical therapy is questionable. Additional therapy includes topical cycloplegic agents and systemic analgesics. The intensive therapy should be continued for 48–72 h. Response to therapy could be measured by improvement in symptoms, reduction of congestion, and reduction in anterior chamber reaction. Once there is response to initial therapy, the frequency of antibiotic instillation can be reduced to two hourly administrations.

Once the blebitis resolves, the topical antibiotics should be stopped and never be tapered, and chronic use of antibiotics should be avoided, both of which could result in colonization of resistant microorganisms on the ocular surface. The empirical treatment should be initiated at the earliest and should not be delayed for microbiology workup and results. However, the subsequent microbiology results would guide in continuation of treatment or choosing alternative medications based on the sensitivity reports.

In the presence of AC involvement (stage II) or vitreous involvement (stage III), vitreoretinal surgeon’s opinion and help with management would be required. It is prudent to begin intensive topical treatment similar to the treatment of blebitis before the referral.

One must remember that the management pearls of the Endophthalmitis Vitrectomy Study (EVS) for post-cataract surgery endophthalmitis cannot be applied to patients of endophthalmitis after glaucoma filtration surgery, more so in late-onset disease. A pars plana vitrectomy (PPV) and intravitreal antibiotic injection is more definitive treatment than a vitreous biopsy with intravitreal antibiotics. Studies have shown that more often poorer visual results (eyes with no light perception) are associated with the vitreous tap group compared to vitrectomy group [7, 28, 29]. Following vitrectomy one should continue treatment with frequent instillation of fortified antibiotic covering both gram- positive and gram-negative organisms till microbiology results are available. In addition, systemic antibiotics must be used. Topical and/or oral corticosteroids can be started after 24–48 h to decrease inflammation and scarring and to preserve the bleb function [7].