Comment on: Relative efficacy of intracameral moxifloxacin injection methods

We read with great interest the article by Arshinoff and Shi evaluating the efficacy of moxifloxacin preparation and injection methods.1 Dr. Arshinoff has made significant contributions in the use of intracameral antibiotics to reduce the incidence of postoperative endophthalmitis, and the efforts to standardize administration are commendable. Drs. Arshinoff and Shri provided an excellent analysis of the appropriate injecting volume of the solution based on the concentration to deliver 500 μg of moxifloxacin while minimizing toxicity during cataract surgery. While moxifloxacin is recognized as being safe in patients with pseudophakia, there are isolated reports of suspected moxifloxacin toxicity when used intracamerally in patients with phakia.2,3 Specifically, the suspected moxifloxacin toxicity involves the development of iris transillumination defects, liberation of iris pigment, elevated intraocular pressure, and mydriasis. This presentation is distinctly different from toxic anterior segment syndrome and is more consistent with reports of ocular toxicity seen with systemic moxifloxacin. Given moxifloxacin’s high affinity and tendency to accumulate in melanin-rich tissues, including the iris, intraocular damage after use is particularly troubling. The correlation in findings with moxifloxacin-induced bilateral acute iris transillumination (BAIT) increases the suspicion that moxifloxacin itself, as opposed to potential impurity in the formulation, may be responsible for these adverse changes.4 Phakic procedures, including some minimally invasive glaucoma surgeries and, in particular, implantable collamer lens procedures, have gained popularity. As these surgeries become more commonplace, the use of moxifloxacin in such cases deserves special attention. While it is believed that moxifloxacin concentration alone is responsible for toxicity, time in contact with the iris pigment epithelium is likely an additional factor along with a reduced rate of dilution that may occur in phakic eyes. Intraoperative use of miotic agents may also be a contributing factor. Given the elective nature of such procedures and the inherently low endophthalmitis rate, the use of intracameral moxifloxacin in the volumes suggested (0.5 to 0.6 mL × 150 μg/0.1 mL) should be carefully considered when operating on an eye that is to remain phakic. While there are other potential etiologies, considering reported cases to date, and the known systemic associations of moxifloxacin, intracameral moxifloxacin toxicity in patients with phakia may be an under-reported occurrence. Based on the available data, we advise exercising caution with recommendations of volume and concentration of intracameral moxifloxacin in cases where patients remain phakic. Although briefly mentioned in the article, the pseudophakic nature of the patients being discussed should be emphasized. There is ample evidence demonstrating the efficacy of lower concentrations of moxifloxacin in reducing the rate of endophthalmitis, and we would consider the postoperative lens status of the patient when determining the volume and concentration of moxifloxacin used.5