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Study: New fluoroquinolone effective
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SEATTLE – A new fluoroquinolone has been found to work just as well as other ophthalmic fluoroquinolones against bacterial infections, according to a poster presented here at Optometry’s Meeting.
“A significantly higher rate of clinical resolution and bacterial eradication was observed in besifloxacin-treated eyes as compared to vehicle-treated eyes,” Paul M. Karpecki, OD, FAAO, and colleagues concluded in the poster. Primary Care Optometry News Editor Michael D. DePaolis, OD, was one of the study authors.
The novel fluoroquinolone and antimicrobial agent developed by Bausch & Lomb is being investigated for the topical treatment of bacterial conjunctivitis in this multicenter, randomized, double-masked parallel group study, according to the poster.
Patients with clinical manifestations of bacterial conjunctivitis were randomized to receive either besifloxacin (n = 137) or another vehicle (n = 132) three times a day for 5 days.
“Clinical resolution, defined as the absence of conjunctival discharge, bulbar conjunctival injection and palpebral conjunctival injection, was observed in 61.7% (37/60) vs. 35.7% (20/56) of subjects randomized to besifloxacin and vehicle, respectively, at visit 3 (P = .0013), and 23.3% (14/60) vs. 14.3% (8/56) of subjects randomized to besifloxacin and vehicle, respectively, at visit 2 (P = .3144),” the poster said. “Treatment with besifloxacin was well tolerated, with the frequency of adverse events similar to that with vehicle. There were no differences in visual acuity or ophthalmoscopy findings.”
Hypercapnia reduces IOP
In another poster, researchers showed that hypercapnia, or increasing the blood concentration of carbon dioxide by rebreathing into a paper bag, causes a significant reduction in IOP.
“This is a way to look at a possible mechanism for the reduction of IOP that results after exercise,” James LaMotte, OD, PhD, told Primary Care Optometry News in an interview.
Researchers took the baseline IOP measurements of 14 young, normal patients with Goldmann tonometry and a second measurement after those same patients rebreathed into a paper bag for 10 minutes. Measurements were taken again 7 minutes later.
The change of IOP from baseline after 10 minutes was not statistically significant in either the right eye (P = 0.089) or the left eye (P = 0.055), but the change from baseline to the final measurement was significant. The right eyes went from 14.1 mm Hg average at baseline to 13.1 mm Hg after 7 minutes of normal breathing, and the left eye dropped from a 14.2 mm Hg average to 12.9 mm Hg.
Dr. LaMotte said it is well known that moderate aerobic exercise results in a significant reduction of IOP, but the mechanisms of how that works are still not understood. It can be surmised from this research that exercise-induced hypercapnia may be involved, but “the next step would be to see how long the IOP-lowering effects would last,” he said.
Tonometers should be calibrated often
Researchers investigating the usage of Goldmann tonometry devices at an optometry college found that most practitioners are unaware that those machines should be calibrated quite often for best results. Otherwise, with the wrong measurements due to poor calibration of the instrument, “glaucoma might be diagnosed later than it could be,” David M. Perrigen, OD, told PCON. “Reading too high or too low gives you a false sense of security.”
The researchers measured 74 Goldmann applanation tonometers at the University of Houston College of Optometry’s University Eye Institute for calibration accuracy at the 20-mm Hg and 60-mm Hg settings, both at 2 weeks and 5 months.
“By the 2-week evaluation, a significant number had drifted outside the recommended range for the 20-mm Hg setting (P = 0.039), but not for the 60-mm Hg settings (P = 0.404),” according to the poster abstract. “At 5 months, the degree of errors and the number out of calibration had increased. Fifty percent of tonometers off at the 20-mm Hg setting were now also out of calibration at the 60-mm Hg setting.”
They found that the inferior mounted devices were more likely to be out of calibration after 5 months.
The instruments come with devices that help determine calibration, but it is not easily understood how often those devices should be used, Judith A. Perrigen, OD, FAAO, said.
“We need to make sure that [information] is incorporated,” she said. “Yearly checks are not adequate.”
For more information:
- Paul M. Karpecki, OD, FAAO, is director of research in Cornea and External Disease Service for Cincinna ti Eye Institute and a member of the Editorial Board of Primary Care Optometry News. He can be reached at Cincinnati Eye Institute, 580 S. Loop Rd., Suite 200, Edgewood, KY 41017; (859) 402-2814; fax: (859) 331-9040; e-mail: paul@karpecki.com. Dr. Karpecki is a consultant for Bausch & Lomb.
- James LaMotte, PhD, OD, can be reached at the Southern California College of Optometry, 2575 Yorba Linda Blvd., Fullerton, CA 92831; e-mail jlamotte@scco.edu.
- Judith A. Perrigen, OD, FAAO, can be reached at the Texas Eye Research and Technology Center, University of Houston College of Optometry, 505 J Davis Armistead Building, Houston, TX 77204; (713) 743-1948; e-mail jperrigen@uh.edu.