EyeWorld India March 2019 Issue

31 March 2019 EWAP CATARACT / IOL Distinguishing TASS from endophthalmitis by Lauren Lipuma EyeWorld Contributing Writer Expert discusses ways to differentiate between the two potentially damaging diseases T oxic anterior segment syndrome (TASS) and endophthalmitis are serious complications of cataract surgery that can damage intraocular structures and lead to vision loss if not treated properly. The two diseases can present with similar symptoms but their management differs dramatically, so it’s important for cataract surgeons to be able to distinguish between them, according to a retina expert who presented at the 2018 ASCRS•ASOA Annual Meeting. Ron Adelman, MD, director of the retina and macula service, Yale University School of Medicine, New Haven, Connecticut, discussed common causes of TASS and ways to differentiate it from endophthalmitis in his presentation during the “Retina Essentials for Cataract and Refractive Surgery” symposium. The etiology of TASS is broad and includes any substance used during or immediately after anterior segment surgery that can be toxic to the eye, Dr. Adelman said. Intraocular solutions like balanced salt solution are a common cause; any abnormality in pH, osmolarity, ionic composition, or additives such as epinephrine or antibiotics can cause a reaction. Even topical drops can be a culprit; preservatives or stabilizing agents that may be toxic to the endothelium can cause TASS if given access to the anterior chamber. Preservatives like benzalkonium chloride (BAK) in OVDs, bisulfate stabilizing agents and methylparaben in lidocaine have all been linked to TASS outbreaks. Residual OVD not flushed properly from the eye can be broken down into unfavorable components during sterilization or may retain detergents or enzymes from sterilization and be introduced into the anterior chamber, Dr. Adelman said. Autoclaving at a high temperature does not always inactivate these substances, so be sure to flush the OVD completely from the eye and use disposable cannulas, he said. One percent methylparaben- free lidocaine is now the most commonly used topical numbing agent and not associated with TASS, he added. Antibiotics and ointments placed on the eye can be toxic, so must not be allowed to gain access to the anterior segment, according to Dr. Adelman. “Wounds that are poorly constructed and not watertight may allow ingress of topical solutions into the anterior segment, leading to toxic damage,” he said. Making a diagnosis Unfortunately, there is no way to differentiate between TASS and endophthalmitis 100% of the time, Dr. Adelman said. However, physicians can use some criteria to help them make a diagnosis. TASS symptoms usually start 12 to 24 hours after surgery, while postoperative endophthalmitis usually presents within 2 to 7 days because it takes time for bacteria to proliferate. TASS is rarely painful, but lack of pain cannot rule out endophthalmitis, Dr. Adelman said, because about 25% of endophthalmitis patients won’t experience pain. The hallmark of endophthalmitis is vitritis, and vitreous cultures are usually positive. TASS cultures should always be negative and the vitreous should be clear, Dr. Adelman said. Physicians can also assess the appearance of the cornea; with TASS, limbus to limbus corneal edema is common, but with endophthalmitis, the edema usually doesn’t extend that far. If you rule out endophthalmitis and determine the patient does have TASS, be on the lookout for more cases because cases are usually clustered, said Timothy Olsen, MD, Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota. When you get one case of TASS, go through every detail of the operating room to try to find the source compound that’s causing a reaction, Dr. Olsen said. Steve Charles, MD, Charles Retina Institute, Germantown, Tennessee, advised using disposable cannulas rather than reusable ones. Residual OVD material can linger in the lumen of a reusable cannula and cause TASS in the next patient it’s used on. If physicians are worried about cost, it seems counterintuitive but sterilizing and reusing cannulas actually costs more than using disposable ones because of the labor costs associated with cleanup, Dr. Charles said. Using disposable cannulas ensures there will be no residual OVD and will cost less overall, he said. Treating the patient If a patient’s symptoms resemble TASS or endophthalmitis, the most important thing to do is to first rule out infection, according to Dr. Cornea is hazy secondary to corneal edema; hypopyon noted in the inferior anterior chamber. Source: Mohammad Rafieetary, OD Continued on page 32