Intraocular vancomycin levels after intravitreal injection in post cataract extraction endophthalmitis

Purpose: Intravitreal antibiotics are the mainstay of treatment of endophth almitis following cataract surgery. The purpose of this study is to determi ne the range of intraocular vancomycin found after intravitreal therapy and assess the optimum time for repeat injections. Methods: Aqueous and vitreous vancomycin was assayed at the time of reinjec tion in 14 patients with endophthalmitis showing a poor clinical response a fter their primary injection. Nine patients received vancomycin 2 mg and an other five received vancomycin 1 mg. In six patients the injection was repe ated at 48 hours and in seven at 72 hours, Two patients received three inje ctions. Results: Aqueous vancomycin varied from 8.4 to 170 mg/L and the vitreous va ncomycin level ranged from 21.2 to 220 mg/L. Conclusions: In the current study vitreous vancomycin levels were variable, but well within the therapeutic range for sensitive Gram-positive organism s. At times they exceeded the putative retinotoxic levels (100 mg/L). Highe r aqueous levels were found after an injection of 2 mg than after 1 mg. Van comycin levels were still very high 3 days after injection of 2 mg where re sults were available. Assay at the time of repeat injection may provide ins ight into the adequacy of vitreous levels and guide future therapy.