Sutureless, clear corneal incisions and unplanned anterior vitrectomies increase the risk 10x, while poor sterility-maintenance techniques by the surgeon can also contribute to a higher chance of the condition appearing. Counter-intuitively, operations by trainees and procedures that run overtime, have not been shown to be causative factors.Preventitive measures are mostly logical; hand washing, periocular antisepsis including the use of povidone-iodine conjunctival irrigation, careful draping with sequestering of lids and lashes, topical antibiotic prophylaxis using a 4th generation fluoroquinolone, and intracameral antibiotics. No evidence supports the mixing of an antibiotic into the irrigating infusion, and so far, no prospective study has supported the use of sub-conjunctival antibiotics.{{image3-a:r-w:300}}Currently, the preferred prophylactic antibiotic is ceruroxamine, which has been shown to decrease the incidence of endophthalmitis by 5.86x. The architecture, location, and integrity of the wound is important because a ‘Day 1’ wound is known to increase the risk of endophthalmitis by 44x. Risk is also increased by the use of tporal clear corneal incisions.It’s also important to avoid contact between any ocular surface, the surgical tools, and the IOL. As soon as endophthalmitis is suspected, a tap and inject technique using a 23-gauge needle is ployed under local anaesthesia to inject ceoazidime/vancomycin intravitreally (behind the IOL) and to sample (0.2 mL) the vitreous for biopsy purposes. The anterior chamber may also be tapped for a sample, the results of which usually govern re-injection of antibiotics. Commonly, the eye looks worse on the second day.Similar to victrectomies in cases of VH, victrectomies in endophthalmitis tend to be done earlier because of the advantage of roving bacteria, inflammatory debris, and toxins. It also offers antibiotics better diffusion, all of which leads to more rapid vision recovery.Obviously, intravitreal injections are not without risk and because of their frequency in many scenarios, the cumulative nature of that risk warrants consideration. In widely reported studies such as MARINA, ANCHOR, and CATT, the cumulative risks ranged from 0.5–1%.Frustratingly, when taps were cultured, one-third were culture-negative in a Sydney Eye Hospital study. Staphylococcus epidermis and S. aureus accounted for more than 37% of the culture-positive cases, followed by Streptococcus spp. at almost 16%. It would appear that the latter’s involvent led to worse visual outcomes due to retinal pathology and a 17x greater chance of losing an eye.As an added precaution, operating staff wear masks because of the known probl of the aerosolation of saliva from operating table conversations. Counter-intuitively, post-operative antibiotics do not reduce the risk of endophthalmitis and may actually be harmful.In a Sydney Eye Hospital study of early vitrectomies for endophthalmitis performed just 0.8 days on average after diagnosis, just two patients (3%) lost an eye. Good communication, including with a vitreoretinal surgeon and an early diagnosis are central to good outcomes, while proper and detailed records are essential to manage the risk, as is an after-hours ergency contact syst, and proper valid operating procedures.Chang’s parting comments included: the need for prophylaxis, the maintenance of a high index of suspicion, a recommendation to top and inject without delay once suspicions are raised in the hope of facilitating an early diagnosis, and early intervention which might include an early vitrectomy.During question time, he advised against the bilateral use of any product compounded by outsiders and, if using mainstream products bilaterally, he suggested the use of products from two different batches as a precaution against the possibility of bilateral medical misadventure due to faulty products.
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Associate Professor ANDREW CHANG is a Vitreoretinal subspecialist ophthalmologist and Head of the Retinal Unit at the Sydney Eye Hospital. He holds an acadic appointment of Clinical Associate Professor at the University of Sydney, and professional awards include the Achievent Award and Distinguished Service Award of the Asia Pacific Acady of Ophthalmology (APAO) and the RANZCO Excellence in Teaching Award. |
