Open-globe injury has about a tenfold higher rate of infection compared to intraocular surgery. Among infectious endophthalmitis, post-traumatic endophthalmitis comprises up to 31 % of cases. Several reviews have reported higher rates of infection with vegetable or organic IOFB than metallic ones [1]. However, a report from the National Eye Trauma System (NETS) Registry did not see significant difference among various types of IOFB [2]. The number of reported endophthalmitis has decreased through the years with the development of more effective antibiotics and improved prophylactic management.

Risk of postsurgical endophthalmitis can be due to factors inherent in the patient, surgical technique, and postoperative course as enumerated in Table 8.2 [3].

Among factors inherent to the patient, pre-existing periocular infections such as bacterial blepharitis and dacryocystitis can increase the risk of aqueous contamination during surgery.

Bacterial contamination of the aqueous may also occur from improperly sterilized instruments, contaminated surgical field and fluids, and use of intraocular lenses (IOLs) with polypropylene haptics and silicone implants. IOLs made from the aforementioned materials have a higher risk of bacterial adherence compared to polymethyl methacrylate and acrylic hydrophobic IOLs [4–6].

Clear corneal incision, likewise, increases the risk two- to threefold more than corneoscleral incision (0.13 %) [7]. Prolonged and complicated surgery with posterior capsular rent and/or vitreous loss may increase risk of aqueous bacterial contamination. Postoperative factors that increase likelihood of endophthalmitis are due to wound abnormalities such as vitreous wick, wound leaks, and infected wound edges (Fig. 8.2).

Acute postsurgical endophthalmitis may present with progressive eye pain, conjunctival congestion, and decreased visual acuity. Examination would show anterior chamber inflammatory cells with fibrin formation, hypopyon (Fig. 8.3), vitreous cells, and fibrin [8].

Chronic post-cataract surgery endophthalmitis presents as a milder disease that causes loss of vision and mild eye pain. Presenting signs include cells in the anterior chamber, hypopyon, and a plaque on the posterior chamber capsule. Mild vitritis is also sometimes present.

Intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) into the vitreous cavity carries a small risk of postinjection endophthalmitis. Symptoms occur within 1–6 days after injection with around 80 % presenting with hypopyon [9].

A particular kind of postoperative endophthalmitis is filter-bleb-associated endophthalmitis. It is one of the long-term complications of trabeculectomy that has major implications for visual loss. It occurs as a sequela to blebitis. Presenting signs and symptoms are similar to other forms of infectious endophthalmitis, in addition to mucopurulent material seen in the filtering bleb [10] (Fig. 8.4).

The most common pathogen in postsurgical endophthalmitis is coagulase-negative Staphylococcus. The Early Vitrectomy Study (EVS) examined cases of post-cataract surgery endophthalmitis and found that infection caused by more virulent strains such as gram-negative organisms and gram-positive organisms other than coagulase-negative Staphylococcus presented within 2 days of surgery and with worse symptoms [11].

The principal step in treating postsurgical endophthalmitis is with intravitreal injection of antibiotics (Table 8.3). The intravitreal antibiotics of choice are vancomycin (1 mg) for gram-positive coverage and amikacin (0.4 mg) or ceftazidime (2.25 mg) for gram-negative strains. A single dose is usually sufficient to control infection. Poor or none response to treatment may be due to infection with virulent organisms, like Streptococci sp. and Pseudomonas, and resistant organisms. In cases of poor clinical response, a second intravitreal injection is recommended after 48 h. Since repeated injections of these antibiotics suggest increased risk of retinal toxicity, this practice is not recommended unless necessary.

Vitrectomy helps to restore media clarity faster, obtain a better sample for culture, and remove bacterial toxins and inflammatory cells. The EVS remains to be the most extensive prospective trial that studied several aspects in management of post-cataract endophthalmitis. In their study to compare the benefit of performing vitrectomy over vitreous tap alone, they found that there was no apparent benefit to doing vitrectomy in patients with hand motion vision or better [12]. Still, vitrectomy is preferred by some surgeons in patients with severe visual loss or rapidly deteriorating vision and those where virulent bacteria has been isolated.

Fortified antibiotic eyedrops and/or fourth-generation fluoroquinolones may also be given, adjunctively, every 1–4 h as topical treatment. Subconjunctival antibiotics, likewise, may be injected to decrease bacterial load in aqueous although this is less often applied (Table 8.3).