Intraocular penetration of vancomycin eye drops after application to the medial canthus with closed lids

Aims-To investigate the intraocular penetration of vancomycin eye drops and to compare the conventional method of drop instillation to the lower cul d e sac with applying drops to the medial canthus with closed lids. Methods-This prospective randomised trial evaluated 53 eyes of 53 patients who had undergone extracapsular cataract extraction (ECCE) with intraocular lens implantation. Vancomycin (50 mg/ml) eye drops were applied to either the lower cul de sac with open lids (conventional method), or to the medial canthus with the patient in a supine position and with closed lids; After paracentesis performed during ECCE, an aqueous humour sample was taken and vancomycin concentration was measured using the TDX vancomycin assay (fluor escence polarisation immunoassay). Results-Vancomycin concentration in the anterior chamber were above the min imal inhibitory concentration for Gram positive bacteria in the two methods of drop instillation examined (2.04 (SD 1.9) mu g/ml and 1.49 (1.1) mu g/m l in the open and closed methods, respectively (p=0.202)). Conclusions;Vancomycin (50 mg/ml) reaches therapeutic concentration in the anterior chamber after topical drop application. Comparable concentrations were reached when drops were applied in either the lower cul de sac or to t he medial canthus with closed lids. The latter method is proposed as likely to improve patient compliance.