In a retrospective evaluation of patients who received intravitreal injections (IVIs) at a single hospital in Canada, those who underwent alcohol-based chlorhexidine antisepsis prior to injection were more likely to develop endophthalmitis than those who received povidone-iodine. These findings suggest that alcohol-based chlorhexidine prophylaxis may be suboptimal for IVIs, although the exact relationships and reasons behind these observed trends require additional investigation.
Study Design
This single-center retrospective cohort study compared the rate of post-injection endophthalmitis when using 0.05% chlorhexidine with a 4% alcohol base (CH) vs 10% povidone-iodine (PI) as a pre-IVI antiseptic. Between May 2019 and October 2022, 31,135 IVIs were performed using CH and 139,817 were performed using PI. All patients in the CH arm were started on CH due to apparent PI intolerance.
Outcomes
Among the 170,952 total IVIs performed on 14,395 patients, 49 cases of endophthalmitis were reported (0.029%). The rate of endophthalmitis was significantly higher in the CH group (0.064%, 20 cases) vs the PI group (0.021%, 29 cases).
Limitations
Intravitreal techniques employed in this study may have increased the overall risk of endophthalmitis in both arms of this study. First, an assistant held the lids, rather than using a lid speculum. Second, vial-splitting was performed for all anti-VEGF medications which, although done by a compounding pharmacy, may increase risk. Third, no antisepsis was given prior to the subconjunctival numbing injection. Fourth, the top of each patient’s face mask was not taped down prior to IVI. Multiple-use vials of CH and PI were also employed, rather than single-use vials. Other limitations of this study include the relatively small proportion of patients in the CH arm (16%), the study’s retrospective nature, and the potential for missed endophthalmitis cases from loss to follow up.
Clinical Significance
The increased risk of endophthalmitis in the CH arm as compared to the PI arm underlines the importance of continuing to use PI as the antiseptic for all IVIs until additional data is available. Patients marked as allergic to PI can often tolerate the brief topical application with complete flushing of the PI following the procedure.
Financial Disclosures: Dr. Lisa Schocket discloses no financial relationships.