This retrospective review describes the optimal dose, pharmacodynamics and administration technique for an intracameral moxifloxacin prophylaxis used successfully in more than 4,500 consecutive cases.
The protocol was developed by 2 physicians at a single eye hospital after findings linked generic intracameral vancomycin to toxic anterior segment syndrome (TASS) in 2004.
Between 2004 and 2010, 3,430 eyes undergoing cataract surgery by a single surgeon were given 100 mcg moxifloxacin in 0.1-mL balanced salt solution (BSS), injected through the side port after the main incision had been sealed and hydrated. During this period, there was 1 case of endophthalmitis caused by a moxifloxacin-resistant Staphylococcus epidermis, an incidence rate of 0.029%.
In 2010, the authors revised their dilutions to achieve higher inhibitory concentrations. Under the updated protocol, eyes received 450 to 600 mcg moxifloxacin in 0.3- to 0.4-mL BSS. There were no reported cases of endophthalmitis or antibiotic-related complications in the subsequent 4,601 cataract surgeries performed between 2010 and 2016.
Using an aqueous concentration model, the authors calculated that the new dose delivers aqueous antibiotic concentrations 10x higher than the MIC of the most resistant strain ever reported, lasting for 1 hour after injection. This dose is estimated to retain intracameral levels exceeding the MIC of the 2010 patient’s strain for more than 4 hours after injection, whereas the 100-mcg injection retains that level for only 3 hours.
The updated protocol uses a full 3-mL bottle of moxifloxacin (Vigamox) diluted with 7 mL of BSS to achieve a concentration of 150 mcg/0.1mL, of which 0.3 to 0.4 mL is injected into the anterior chamber as the last step of surgery described above.
In light of recent findings linking vancomycin to hemorrhagic occlusive retinal vasculitis (HORV), physicians must consider validated and safe alternative prophylactic protocols. Although this study was not a randomized control trial and so cannot offer a statistically significant analysis of outcomes at the 2 different concentrations, it does give guidance based on the experience of a surgeon using moxifloxacin in more than 8,000 cases.