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Moxifloxacin offers good penetration, potency in refractive lens surgery
Vigamox has the highest penetration of any ophthalmic antibiotic, according to a study.
Moxifloxacin is an effective antibiotic for prophylactic use in refractive lens surgery, protecting against ocular infections while maintaining a low toxicity level, according to Edward J. Holland, MD.
Dr. Holland said in a telephone interview with Ocular Surgery News that he has used Vigamox (moxifloxacin HCl ophthalmic solution 0.5%, Alcon) in several thousand patients. He said the product is well tolerated and has minimal toxicity, making it safe to use in refractive surgery.
“There was a concern that as the antibiotic concentration was increased with more effective versions, we reached higher toxicity levels. Vigamox penetrates extremely well and gets very high concentration in the ocular tissue, yet we’re not seeing any toxicity,” Dr. Holland said. “I feel comfortable that I have an antibiotic that has the best penetration, the best potency, with no significant toxicity.”
He explained that reducing risk of infection is key to safe, effective lens surgery, whether cataract surgery, refractive lens exchange or phakic IOL implantation. He said surgeons should approach all patients the same. Differences in the risk-benefit ratio exist, however, between cataract surgery patients, who have marked visual loss, and refractive surgery patients, who are undergoing surgery to correct some type of refractive error, Dr. Holland said.
“These patients have good vision with correction,” he said. “So I think the bar is raised a bit. But I think with all patients, clinicians should look at what they do and do all they can to have a great outcome, including reducing risk of infection.”
Two factors
According to Dr. Holland, there are two important factors in reducing the risk of infection with antibiotic prophylaxis: potency and penetration. He said moxifloxacin has the highest penetration of any topical antibiotic used in ophthalmology, according to a study.
Dr. Holland took part in a multicenter corneal transplant study that was presented at the Ocular Microbiology and Immunology Group Meeting in 2005. The study showed that extremely high levels of moxifloxacin can be found in the conjunctiva, cornea and anterior chamber after one instillation of the drop, he said. Patients in the study were randomized, receiving either one drop of moxifloxacin or gatifloxacin ophthalmic solution 0.3% (Zymar, Allergan) preoperatively. Patients then proceeded to the operating room, where the corneal transplant was performed. Samples from the aqueous and cornea were analyzed for concentration of antibiotic.
Researchers found that anterior chamber levels of moxifloxacin exceeded almost all the minimum inhibitory concentrations of organisms, including those that most often cause endophthalmitis. Moxifloxacin had a more than three times higher concentration in the cornea and anterior chamber than gatifloxacin, Dr. Holland said.
He also said well over 90% of all infections associated with endophthalmitis are caused by gram-positive organisms, which moxifloxacin protects against. That could, logically, lead to a hypothesis that the drug protects against endophthalmitis, he said.
“We know the organisms, and we can tests the minimum inhibitory concentrations of the antibiotics, so we know that Vigamox has the best potency against endophthalmitis, and we know it penetrates. Certainly this information would give good evidence that it’s a very good selection for prophylaxis against endophthalmitis,” Dr. Holland said.
Effectiveness
Dr. Holland said several preoperative and intraoperative practices can enhance the effectiveness of antibiotics.
Preoperative evaluation of the patient to look for risk factors for endophthalmitis is important, he said. Untreated blepharitis has been shown to be a risk factor. It should be treated with lid hygiene and topical antibiotics and ointments to the lid to improve the ocular surface and the lid function before surgery, he said. Dry eyes should also be treated.
Intraoperatively, proper draping of a patient isolates the lid margin and the lashes. The combination of preoperative antibiotic drops with povidone-iodine also is effective, he said. Studies have shown that povidone-iodine significantly reduces the ocular surface bacterial count in combination with antibiotics.
“There are several things you can do to reduce the risk, and topical antibiotics are one part of the puzzle,” he said.
For more information:
- Edward J. Holland, MD, can be reached at 580 South Loop Road, Edgewood, KY 41017; 859-331-9000; e-mail: eholland@fuse.net. Dr. Holland is a consultant for Alcon.
- Alcon Inc., maker of Vigamox (moxifloxacin HCl ophthalmic solution 0.5%), can be reached at 6201 South Freeway, Fort Worth, TX 76134; 817-293-0450; fax: 817-568-6142; Web site: www.alconlabs.com.
Reference:
- Kim, Lane, Holland, Raizman, et al. Human cornea scleral stroma and epithelium concentration of moxifloxacin and gatifloxacin following topical ocular dosing with Vigamox and Zymar. Presented at: Ocular Microbiology Immunology Group Meeting; Oct. 15, 2005.
- Erin L. Boyle is an OSN Staff Writer who covers all aspects of ophthalmology.