Research Digest

■ Gatifloxacin Less Prone to Fungi Than Moxifloxacin

The results of a study presented in May at the annual meeting of the Association for Research in Vision and Ophthalmology in Fort Lauderdale, Fla., showed that gatifloxacin (Zymar, Allergan) is less likely to be contaminated by fungus than moxifloxacin (Vigamox, Alcon) during routine use. The two antibiotics, regularly used after phacoemulsification to prevent infection, were cultured from bottles, spouts and caps, and gatifloxacin was less conducive to growing fungus.

Stephen E. Pascucci, M.D., the medical director of Eye Consultants of Bonita Springs, Fla., and a consultant to Allergan, says the concept for a study about bottle contamination arose as reports of contamination that "seemed to be fungal in nature" were reported. "This could impact treatment plans when a patient presents with suspected endophthalmitis, as we do not typically think it's fungus," Dr. Pascucci says.

"We are unaware of the methods patients use at home when they instill eyedrops. Fungi are ubiquitous and the potential for contamination of eyedrops is real. This is especially true in the immediate postoperative period," Dr. Pascucci notes.

Regarding the study, Dr. Pascucci says, "We wanted to simulate a normal post–cataract-surgery situation. We wondered when patients returned after a week or so of routine drop use if their antibiotic or container would really be contaminated with fungus."

When 68 bottles of either moxifloxacin 0.5% or gatifloxacin 0.3% were compared, fungal contamination was six times higher for the moxifloxacin bottles (P=.028). The tendency for greater contamination in moxifloxacin also appeared when spouts and caps (P=.039 and P=.142, respectively) were cultured. Also notable was that two bottles of moxifloxacin 0.5% grew fungus, while none of the gatifloxacin bottles did (P=.521). While none of these P-values was lower than a statistically significant .001, Dr. Pascucci says the numbers indicate a trend. "If you increased the sample sizes," he says, "you'd likely see lower P-values."

A key consideration with this study is the inclusion of benzalkonium chloride (BAK) in gatifloxacin. Asked whether the presence of BAK in gatifloxacin might have had an antifungal effect, Dr. Pascucci says, "BAK alone does not have sufficient anti-fungal or anti-bacterial efficacy but it shows a synergistic effect when combined with a fourth-generation fluoroquinolones such as gatifloxacin 0.3%. My impression is that this study indicates that BAK offers a protective effect against potential fungal contamination of antibiotic eyedrops." OM

■ Paper Addresses Phaco in Uveitis Patients

A paper published online by the British Journal of Ophthalmology found that, of 101 uveitis-afflicted eyes studied, the majority improved in visual acuity after phacoemulsification. There were also impressive results in several risk factors.

Mostafa A. Elgohary, M.D., the first author in the study, tells Ophthalmology Management that the results of the study were "not particularly surprising but confirmatory to what was shown before in the few previous studies of uveitis patients."

"We had a larger group and mix of patients than in the previously published studies. What was new about the study was identifying the presence of macular or optic nerve lesions as a risk factor associated with increased rate of visual loss, which happened in almost 52% the patients over the years after surgery," Dr. Elgohary says.

One intriguing finding was that women were more likely to have postop uveitis. Dr. Elgohary conceded that there was no clear explanation, but he does speculate, "A hormonal influence might have a role. In some previous studies, there was a demonstrable relationship between the estrogen-progesterone hormone levels and the flare-up of uveitis at the latter half of the menstrual cycle and in pregnant women after delivery when the hormone levels drops. Since most of our patients were relatively younger than the general cataract population, this could have been the case."

Commenting on a finding that Nd:YAG capsulotomy for clinically significant posterior capsular opacification (PCO) was more common in patients younger than 55 years old, Dr. Elgohary says, "This [result] is likely to be related mainly to these patients having more lens epithelial cells within their capsular bags. These have more proliferative capacity in younger than older patients."

Also, PCO was higher in patients with hydrogel IOLs than with other IOLs. Dr. Elgohary explains, "The development of hydrogel IOLs was aimed primarily to reduce the magnitude of postoperative inflammation, and that is why they became very popular with diabetic and uveitic patients who are more prone to postoperative inflammation. Soon afterward, however, these lenses were associated with a higher rate of PCO and required Nd:YAG capsulotomy. This is mainly because of their increased hydrophilicity — the same feature by which they reduce postoperative inflammation." OM