A broad definition of endophthalmitis includes any severe intraocular inflammation. Toxic substances, necrotic tumors, noninfectious uveitis, and infarction can create the clinical picture of vitreitis, hypopyon, and ocular pain.

Infectious endophthalmitis can be of bacterial, fungal, or parasitic etiology. Vitreous surgery reduces the number of organisms; reduces the intravitreal load of neutrophils, macrophages, lymphocytes, and soluble mediators; enhances the penetration and diffusion of antibiotics; and aids in identification of the pathogen. Late complications related to cellular proliferation on the vitreous matrix are reduced as well.

Early diagnosis and treatment are of paramount importance when managing a patient with endophthalmitis. It is strongly recommended that all ocular surgery postoperative patients be examined on the first postoperative morning as well as immediately if the patient complains of pain or decreased vision. If the physician cannot personally examine the patient, immediate and definite arrangements can be made with another qualified physician. The welfare of the patient is always the surgeon’s responsibility. Once endophthalmitis is suspected, one can examine the patient often and take definitive action when indicated. While the more common signs of endophthalmitis are well known by physicians, less frequent signs are also important. These include chemosis, lid edema, fibrin membrane formation on the intraocular lens (IOL), and retinal hemorrhages.

ETIOLOGIC SUBGROUPS

Endogenous Endophthalmitis

Endogenous endophthalmitis accounts for a minority of cases (1). Predisposing conditions include immune deficiency, immune suppression, diabetes mellitus, chronic renal failure, IV drug abuse, and patients receiving hyperalimentation. These patients can develop endophthalmitis without prior ocular disease. Such cases may be bilateral, increasing both the impact on the patient and the management difficulties. Systemic workup and therapy play an extensive role in the management of these patients and require infectious disease consultation. Metastatic infection accounts for approximately 8% of endogenous bacterial endophthalmitis. At times, vitrectomy is indicated in this patient group but is quite difficult because of the associated anesthesia risk and the potential bilaterality of the disease. Eyes with endogenous endophthalmitis have increased penetration of systemic antibiotics through breakdown of the blood-retinal barrier, and intravenous antibiotics may be sufficient to treat the disease if the intraocular inflammation is not severe. On the other hand, whenever bilateral endogenous endophthalmitis is diagnosed and rapid progression of the diseases is noticed or one of the eyes has progressed to severe visual loss, the authors often recommend vitrectomy for the less involved eye to prevent bilateral blindness. Adequate coordination with the infectious disease consultants is paramount. If the patient has a known systemic infection, the appropriate intravitreal antibiotic therapy can be chosen. If the infectious agent has not been identified, vitrectomy can permit isolation of the bacteria and guide systemic treatment.

Exogenous Endophthalmitis

Ocular trauma (2,3) accounts for approximately 20% of bacterial endophthalmitis (4,5). Ocular surgery (6–8) accounts for the vast majority (~70%) as it facilitates the introduction of organisms into the eye. Management of trauma cases usually requires vitreous surgery and may involve removal of intraocular foreign bodies. While conventional surgical wisdom suggests removal of any implanted materials if infection occurs, this logic does not apply to the IOL. Removal of an IOL, especially in an endophthalmitis case, has a risk of iris avulsion, endothelial trauma, intraocular bleeding, choroidal expulsive hemorrhage, and retinal detachment. Vitrectomy with intraocular antibiotics without implant removal can be successful in a high percentage of cases. This is probably because the smooth surface of the lens implant coupled with the high fluid throughput of vitrectomy removes all organisms on the lens surface, but organisms may remain in the peripheral capsular bag.

Fortunately, the incidence of acute postoperative endophthalmitis remains relatively low. Extracapsular cataract surgery with or without an IOL insertion carries an incidence of 0.072% (9). Vitrectomy (0.051%) and penetrating keratoplasty (0.11%) have a far less risk than the insertion of a secondary IOL (0.30%). Sutureless clear corneal incisions and temporal placement of phacoemulsification incisions may have an increased risk of postoperative infectious endophthalmitis (10). The most frequent organisms include coagulase-negative Staphylococcus, Staphylococcus aureus, Streptococcus species, and Gram-negative bacteria.

Delayed-onset, post–cataract surgery endophthalmitis is most often caused by Propionibacterium acnes, coagulase-negative Staphylococcus, or Candida. In the setting of P. acnes endophthalmitis, inflammatory plaque and associated capsule must be removed at a minimum; in most instances, the IOL must be removed as well (11).

The incidence of trauma-related endophthalmitis varies with or without the presence of a retained foreign body. Following a penetrating injury, the incidence of endophthalmitis ranges from 3.2% to 7.4%. With a retained foreign body, the incidence jumps to 6.9% to 13% (metallic—7.2%, nonmetallic—7.3%, organic—6.3%). The most frequent organisms include Bacillus sp., Staphylococcus sp., and Streptococcus sp.

Streptococcus, coagulase-negative Staphylococcus, and Haemophilus are the most common organisms in delayed-onset filtering bleb–related cases. Immediate vitrectomy intervention is mandatory in these often rapidly deteriorating cases.

Therapeutic intravitreal injections with anti–vascular endothelial growth factor (VEGF) compounds are widespread but fortunately produce a low incidence of postinjection endophthalmitis when meticulous sterile technique is utilized. Fortunately, the incidence of endophthalmitis after intravitreal triamcinolone injections, although higher than anti-VEGF compounds, appears to be low (~0.1%–0.9%) (12,13).

TASS

Toxic anterior chamber syndrome must be distinguished from infectious endophthalmitis because the management and causation implications are vastly different. The incidence after cataract, glaucoma, and corneal surgery is 0.1% to 2.0%, increasing (14) worldwide, and occurring in clusters because of institutional outbreaks. Toxic Anterior Segment Syndrome (TASS) usually is diagnosed within a few hours after surgery; all patients have blurred vision, severe limbus-to-limbus corneal edema (surgical trauma produces localized edema), 4+ flare, possible hypopyon, fibrin, minimal conjunctiva or episcleral hyperemia, and minimal or no pain (75%–80% of endophthalmitis patients have pain). Although TASS typically presents on the first postoperative day, virulent bacterial endophthalmitis can also present on the first postoperative day. Outcomes include glaucoma due to Peripheral Anterior Synechiae (PAS) and trabecular meshwork damage, chronic inflammation, CME, corneal endothelial damage, and iris damage (fixed pupil and transillumination defects).

Causes in general include drugs and devices, process issues, and surgical issues. Device and drug factors include poor-quality infusion solutions (Cytosol and others), intraocular lidocaine, intraocular epinephrine (pH, dose, preservative, stabilizing agents: bisulphites or metabisulphites), intraocular antibiotics (pH, concentration, dose), intraocular Kenalog (active drug and preservative), and poor-quality viscoelastics. Process issues include contamination within steam sterilizer (filters, water chambers, and the inside of autoclave), denatured viscoelastics from resterilized cannulas, bacterial endotoxins from Gram-negative bacteria killed when cannulas are autoclaved, and contamination of ultrasonic cleaner and water baths with enzymes or detergents. Devices designated for single use should not be reused. Additional process causes include endotoxins from tap water, detergent or chemical residue on instruments, and incomplete cleaning of reusable cannulas. Surgical factors include retained lens cortex, iris trauma, iris retractors, viscoelastics, intracameral agents, IOLs, and endocyclophotocoagulation.

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