**9. Toxic anterior segment syndrome (TASS)**

One may need to differentiate between the postoperative endophthalmitis from the less common cases of TASS. The TASS presents acutely within the first 48-hours after surgery with pain and blurred vision. In these cases, there may be diffuse corneal edema of the whole cornea along with endothelial cell damage. One may see evidence of a small hypopy‐ on along with signs of iritis that may result in iris atrophy. TASS is usually a toxic reaction in the absence of any infectious process and occurs in groups following intraocular surgery. [21] Acute endopthalmitis due to Bacillus cereus after cataract surgery have a fulminant on‐ set with extremely high intraocular pressure, corneal edema and intense pain which may look like TASS. [22] However these eyes rapidly progress to develop corneal infiltrates, scleral and uveal tissue necrosis with hyphema, brownish exudates in anterior chamber and necrotizing retinitis within hours despite immediate intra-vitreal antibiotics and vitrectomy. One may see gram-positive bacilli from the aqueous. The organism is sensitive to conven‐ tional antibiotics except penicillin. Because acute onset endophthalmitis due to Bacillus cer‐ eus has an onset within 12 to 24 hours of intraocular surgery, it simulates TASS in the first few hours but then the clinical course of endophthalmitis due to Bacillus cereus is marked by rapidly worsening necrotizing infection, leading to very poor outcomes despite early in‐ stitution of appropriate therapy. [22] One must closely observe every case of TASS that presents with intense pain and extremely high IOP and rule out acute post-operative en‐ dophthalmitis due to Bacillus cereus with microbiologic testing.

Different causes of TASS have been reported and timely action is required for proper diag‐ nosis and treatment. Variety of stimuli including bacterial endotoxin (lipopolysaccharide cell wall of Gram-negative bacteria) from water within the ultrasound machine used for in‐ struments cleaning or even from contaminated but sterile water used to make steam in an autoclave and viscoelastic materials used can cause TASS. TASS may also be due to agents stuck to devices that have become denatured, the wrong concentration of antibiotics used in the Basic Saline Solution (BSS) irrigating solution during intraocular surgery, use of drugs containing preservatives, BSS made up at the wrong pH, or ethylene oxide residue left on plastics. It is recommended that if an outbreak of several cases of TASS occurs, one should investigate the cause and consider stopping similar operative techniques and use of materi‐ als. [3, 21] Techniques of instrument cleaning, sterilization, type of water used for cleaning, autoclaving, and the use of reusable instruments and cannulae may need to be investigated. In these circumstances, representative samples should be collected for endotoxin assay from the various potential sources of TASS. Treatment is given with corticosteroids, which can be used aggressively once infection is excluded by making an anterior chamber tap for micro‐ scopy and culture and PCR testing if available. [21] Early diagnosis and treatment with a course of topical corticosteroids may yield a good visual prognosis.

### **10. Management of acute post-operative bacterial endophthalmitis**

Evaluation and treatment of acute post-operative bacterial endophthalmitis is initiated when such infection is suspected, generally within few hours of patient's presentation. [1-3] In se‐ vere cases, 3-port PPV is recommended depending on the level of visualization. Posterior capsulotomy should be performed and pus and the fibrin material need to be aspirated. Ag‐ gressive surgery is not recommended in these circumstances since these eyes may have con‐ comitant retinal vasculitis and edema which may result in retinal breaks and retinal detachment. Following PPV, intra-vitreal antibiotics are injected. [2, 3] Doses of antibiotics are reduced in cases of complete vitrectomy. In addition, intra-vitreal dexamethasone is also injected to reduce inflammation. [3] The procedure can be performed under general, peribulbar, or retro-bulbar anesthesia. General anesthesia may be indicated in cases of severely inflamed eyes. The use of vitrector may be required in cases of infected vitreous. Following the sampling, antibiotics and corticosteroids are injected through the sclerotomy and the sclerotomy incision may not require any suturing.

### **11. Late-onset post-operative endophthalmitis**

lowing 5030 surgeries without having sub-conjunctival injections. [48] Sub-conjunctival anti‐ biotics may temporarily provide therapeutic levels in the anterior segment but do not penetrate sufficiently into the vitreous cavity, and hence larger retrospective studies did not

A careful wound construction with a minimum wound leakage and the placement of su‐ tures when necessary is recommended to prevent incident of any post-operative infection. [19, 43] Optical coherence tomography may show variations in gaping of un-healed wounds and Indian ink may migrate through un-healed wound into the anterior chamber. Experi‐ ence has shown that it may take upto a week before the epithelial surface heals completely to have the wound become water-tight. Therefore, it may be necessary that post-operatively one may consider addition of topical antibiotics drops. Some studies have suggested that sil‐ icone IOLs may have a three times higher risk of developing post-operative endophthalmitis than acrylic IOLs. On the other hand, hydrophilic heparin-coated IOLs have demonstrated their lower adherence for Staphylococcal organisms to the lens surface. [1-3] In order to re‐ duce the risk of infection following clear corneal incisions, the use of topical antibiotic drops for 1-2 weeks after the surgery has been recommended. [49] Usually broad spectrum antibi‐ otics are used to cover the most commonly encountered microorganism. These antibiotics

One may need to differentiate between the postoperative endophthalmitis from the less common cases of TASS. The TASS presents acutely within the first 48-hours after surgery with pain and blurred vision. In these cases, there may be diffuse corneal edema of the whole cornea along with endothelial cell damage. One may see evidence of a small hypopy‐ on along with signs of iritis that may result in iris atrophy. TASS is usually a toxic reaction in the absence of any infectious process and occurs in groups following intraocular surgery. [21] Acute endopthalmitis due to Bacillus cereus after cataract surgery have a fulminant on‐ set with extremely high intraocular pressure, corneal edema and intense pain which may look like TASS. [22] However these eyes rapidly progress to develop corneal infiltrates, scleral and uveal tissue necrosis with hyphema, brownish exudates in anterior chamber and necrotizing retinitis within hours despite immediate intra-vitreal antibiotics and vitrectomy. One may see gram-positive bacilli from the aqueous. The organism is sensitive to conven‐ tional antibiotics except penicillin. Because acute onset endophthalmitis due to Bacillus cer‐ eus has an onset within 12 to 24 hours of intraocular surgery, it simulates TASS in the first few hours but then the clinical course of endophthalmitis due to Bacillus cereus is marked by rapidly worsening necrotizing infection, leading to very poor outcomes despite early in‐ stitution of appropriate therapy. [22] One must closely observe every case of TASS that presents with intense pain and extremely high IOP and rule out acute post-operative en‐

Different causes of TASS have been reported and timely action is required for proper diag‐ nosis and treatment. Variety of stimuli including bacterial endotoxin (lipopolysaccharide

reveal any additional benefit compared with intra-vitreal antibiotic application.

are administered topically 4-6 times daily.

182 Common Eye Infections

**9. Toxic anterior segment syndrome (TASS)**

dophthalmitis due to Bacillus cereus with microbiologic testing.

Late cases of endophthalmitis after cataract operation are the 2nd most common form of en‐ dophthalmitis accounting for up to one-third cases of endophthalmitis. [1, 13] In the late-on‐ set cases of endophthalmitis, the symptoms are milder and Propionibacterium acnes has been reported to be the cause in majority of cases (Figure 7). Because of the difficulty in cul‐ turing Propionibacterium acnes and the high rate of recurrence, anterior vitrectomy may be necessary. In these cases, one has to perform capsulectomy to remove the nidus of infection and make the area more accessible for the antibiotic penetration. A further advantage of vi‐ trectomy is that adequate material for culturing the causative organism can be obtained be‐ sides obtaining of the capsular bag material as well. [3]

**Figure 7.** An elderly male patient presented with right eye pain, redness and photophobia (a), which was attributed to delayed onset post-operative endophthalmitis requiring intervention (b). After treatment of intraocular infection, patient's symptoms improved (c).
