Mathematical models of intracameral antibiotics for postoperative endophthalmitis (POE) prophylaxis: answering lingering questions

Session Details

Session Title: Cataract Surgery: Complications & Management

Session Date/Time: Tuesday 17/09/2019 | 14:00-16:00

Paper Time: 14:18

Venue: Free Paper Forum: Podium 1

First Author: : S.Arshinoff CANADA

Co Author(s): :    M. Modabber                             

Abstract Details

Purpose:

To utilize mathematical models to address important and lingering questions pertaining to intraoperative intracameral (IC) antibiotics for postoperative endophthalmitis (POE) prophylaxis.

Setting:

York Finch Eye Associates and The Eye Foundation of Canada (Toronto, Ontario, Canada), the University of Toronto (Toronto, Ontario, Canada), and McGill University (Montreal, Quebec, Canada).

Methods:

Literature review and evaluation of our clinical experience with 9,185 consecutive cases with intracameral moxifloxacin was conducted. Our previously presented models of IC antibiotic abatement profiles were used as baseline to assess, 1) the relative validity of published dose-dependent and time-dependent antibiotic ARMOR minimum inhibitory concentrations (MIC90) for common endophthalmitis pathogen strains, 2) the comparative reliability of small volume full-strength (0.1ml of 500μg/0.1 ml) vs. higher volume diluted (0.4ml of 150μg/0.1 ml) IC moxifloxacin injections, and 3) the effect of adding topical moxifloxacin 0.5% eye drops (Vigamox QID) to the postoperative regimen on the attained intracameral antibiotic levels.

Results:

Reported MIC90 s are misleading, as they are calculated differently for time-dependent drugs (i.e. vancomycin and cefuroxime) as compared with the dose-dependent moxifloxacin. This can distort relative efficacy results. Moreover, intracameral administration of the diluted antibiotic to exchange the anterior chamber volume yields greater reliability in achieving the desired intraocular dosing. Administration of post-operative topical antibiotic in addition to intracameral injection provides a small positive increment in the intraocular antibiotic concentration, thus prolonging its bactericidal effect.

Conclusions:

The ability to assess various post-operative scenarios, reflecting local pathogen resistance patterns, using mathematical models can be of great advantage. Our model correlates well with the published objective data. It allows us to answer lingering questions about IC antibiotics, and in turn to better understanding and optimization of clinical practice patterns.

Financial Disclosure:

None