Comparing Prophylactic Intracameral Moxifloxacin Injection Methods

To compare the amount of intracameral moxifloxacin mass remaining in the eye after three common injection methods: 1. 0.1 mL x 500 µg/0.1 mL, 2. 0.5 mL x 100 µg/0.1 mL, and 3. 0.5 mL x 150 µg/0.1 mL, when mixing and anterior chamber leakage are considered.

University of Toronto

The three methods were compared mathematically using standard first order mixing problem mathematics (calculus). A graph was plotted of residual moxifloxacin mass versus injected volume for the three methods.

Method 1 (0.1 mL x 500 µg/0.1 mL) yields a mathematically reasonable result, but it is fraught with potential error of about 20% because of the small volume injected into the anterior chamber. Method 2 (0.5 mL x 100 µg/0.1 mL) yields a suboptimal concentration of Moxifloxacin in the anterior chamber, and only asymptotically approaches the desired 500 µg mass with infinite injection. Method 3 (0.5 mL x 150 µg/0.1 mL) yields the most accurate result, close to 500 µg mass.

Method 3 is the most accurate prophylactic moxifloxacin injection method. The planned volume of injection should be increased to 0.5-0.6 mL x 150 µg/0.1 mL, which will leave 500 µg in the anterior chamber at the completion of surgery, after dilution and exchange are accounted for.