Gentamicin-induced macular toxicity following subconjunctival sutureless 25-gauge vitrectomy

Abstract

Purpose: To describe a case of gentamicin macular toxicity due to subconjunctival injection following 25-gauge vitrectomy. To present a literature review of gentamicin toxicity, and to present the evidence for cross-reactivity between penicillin and cephalosporins. Method: Case report and literature review. Results: A 65-year-old male underwent routine 25gauge vitrectomy for a macula on retinal detachment. At the end of the procedure 0.5ml of sub-conjunctival dexamethasone (4 mg/ml) and 0.5 ml of gentamicin sulfate (40 mg/ml) were given. Post-operatively at day 14 dilated fundal examination revealed retinal pallor throughout the macula, a posterior pole retinal detachment, and three large irregularly shaped full thickness holes within the macula. The left macular OCT demonstrated macular thinning associated with loss of the normal lamellar structure of the retina. Gentamicin was chosen rather than cefazolin due to the patient’s allergy to penicillin (urticaria), and concerns about potential cross-reactivity with cephalosporins. The literature supporting cross-reactivity was reviewed, and the chance of cross-reactivity between first generation cephalosporins and penicillin was closer to 1% than the traditionally quoted 10%, and only if the reaction to penicillin was of the immediate IgE mediated type (anaphylaxis, bronchospasm, angioedema and urticaria) Conclusion: Gentamicin use should be avoided in sutureless transconjunctival vitrectomy. Show more