Abstract
Purpose: :
Endophthalmitis is a rare complication of cataract surgery. This study evaluated the potential of antibiotic-immersed intraocular lenses (IOLs) to effectively inhibit bacteria in vitro. If effective, this could decrease infection risk in cataract surgery without changing surgical technique or prolonging operative time.
Methods: :
Silicone, polymethylmethacrylate/PMMA, and hydrophobic acrylic IOLs were soaked in vancomycin (10mg/mL), ceftazidime (22.5mg/mL), moxifloxacin (5mg/mL), or azithromycin (1.5%) for 5-10 min, 1-2 hrs, 24 hrs, or 1-2 wks. The antibacterial efficacy (bactericidal for vancomycin and ceftazidime, and bacteriostatic for moxifloxacin and azithromycin) of these antibiotic-soaked IOLs was assessed via two methods: inhibition of bacterial growth curves in solution, and modified Kirby-Bauer disc diffusion on agar plates. Bacterial growth curves were determined via measurement of optical density of S. epidermidis in thioglycollate media. Modified Kirby-Bauer involved measuring zonal diameter of growth inhibition on agar plates streaked with S.aureus. Negative controls (unsoaked IOLs) and positive controls (antibiotics alone, at above stated concentrations) were used as applicable.
Results: :
Hydrophobic acrylic IOLs immersed in moxifloxacin, but not other antibiotics, effectively inhibited bacterial growth in solution regardless of duration of antibiotic immersion. A time-dependent effect of moxifloxacin-treated IOLs was confirmed on agar plates. Antibiotic-treated silicone and PMMA IOLs also inhibited bacterial growth in solution. However, only moxifloxacin-soaked silicone lenses inhibited bacterial growth on agar plates. PMMA IOLs on agar plates yielded inconsistent results, but greater time of immersion did correlate with more effective inhibition. Ceftazidime-soaked silicone and PMMA lenses were least effective.
Conclusions: :
Hydrophobic acrylic IOLs passively absorbed and released moxifloxacin, with excellent immersion time-dependent dose-response inhibition of bacterial growth in vitro. The amphipathic nature of moxifloxacin may be responsible for its success with hydrophobic IOLs. Ceftazidime was least effective. PMMA and silicone IOLs were less consistently effective than hydrophobic acrylic IOLs. This study demonstrated the efficacy of passive antibiotic-immersed IOLs in providing antibacterial activity in vitro, highlighting the potential utility of antibiotic-soaked IOLs as a simple, effective method of minimizing endophthalmitis in patients during cataract extraction.
Keywords: antibiotics/antifungals/antiparasitics • intraocular lens • endophthalmitis