Clinical News: MEDICAL AND PRODUCT UPDATES

IOP CONTROL
Studies shed light on intraocular pressure fluctuations

Two studies involving intraocular pressure (IOP) fluctuations were presented at the recent International Glau-coma Symposium meeting in Prague.

The first study found a correlation between the extent of fluctuation in daytime ocular pressure and degree of vision loss. Sixty-four patients with open-angle glaucoma and an in-office IOP below 25 mm Hg were studied. IOP was measured over a 5-day period, both in the office and at home; progression of the disease was then documented over a period averaging 4 years.

The results indicated that IOP fluctuations over the course of the day were common, and that large fluctuations were a significant risk factor for progression of glaucoma. This was true even after adjusting for baseline office IOP, visual field damage, age, race and gender. (Baseline office IOP had no predictive value.) Eighty-eight percent of patients in the upper quartile of IOP fluctuations experienced disease progression, compared to 57% in the lowest quartile.

The second study compared the effect of Xalatan (latanoprost ophthalmic solution) to other medications commonly used to control circadian IOP: timolol, dorzolamide, brimonidine and a combination of timolol and dorzolamide. Twenty patients with open-angle glaucoma and 20 with ocular hypertension received each drug for a month in a random treatment sequence. IOP was measured daily, eight times around the clock, with patients both lying and sitting.

The resulting data showed:

• Compared to baseline, all five drugs significantly reduced IOP at all measured timepoints, except at one timepoint for timolol and two for brimonidine.
• Latanoprost was significantly more effective than timolol at five timepoints and more effective than either dorzolamide or brimonidine at four timepoints. Latanoprost effectively lowered IOP around the clock.
• Ahe combination of timolol and dorzolamide produced a greater reduction in IOP than brimonidine at four timepoints, and a greater reduction than latanoprost at one timepoint.

A study pooling results from three separate studies conducted in Beaver Dam, Wis., Rotterdam, the Netherlands, and the Blue Mountains area west of Sydney, Australia, found that in each of the three locations, tobacco smoking was the only risk factor besides age consistently associated with any form of AMD. Both ex-smokers and current smokers were more likely to have AMD than people who never smoked.

The authors also found that current smokers were more likely to have wet AMD than dry AMD. The prevalence of wet AMD was twice that of dry AMD among the participants in the Beaver Dam and Blue Mountains studies (ages 55 to 86). The Rotterdam study found a somewhat smaller ratio, which the authors believe may be the result of genetic differences.

The study appeared in the April 2001 issue of Ophthalmology.

The LASIK Institute, a nonprofit educational organization located in Boston, recently announced the recipients of its Refractive Research Initiative awards for proposals submitted last year. They are:

• Avni Murat Avunduk, M.D., of the LSU Eye Center in New Orleans. Dr. Avunduk will use confocal mi-croscopy to compare corneal structural changes after myopic LASIK and PRK.
• Isabel C. Bichao, M.D., Ph.D., of the Wilmer Eye Institute at Johns Hopkins University in Baltimore, who will evaluate nighttime visual problems pre- and post-refractive surgery.
• Kenneth R. Ellis, M.D., a resident at the University of California in Irvine, who plans to evaluate LASIK-driven endothelial lamellar keratoplasty.
• David R. Hardten, M.D., F.A.C.S., of Minnesota Eye Consultants, PA, who will study neuroprotective qualities of brimonidine during LASIK.
• Samir B. Shar, M.D., a resident at the University of California in Irvine, who plans to evaluate procurement and eye bank storage of the anterior corneal surface for LASIK flap exchange.
• Edward J. Wong, Jr., M.D., assistant professor and chief of neurological ophthalmology at the University of California in Irvine, who will evaluate nerve growth factor and corneal healing after controlled sensory denervation.

This year's awards totaled $59,000, with no more than $12,000 going to any one project. The deadline for 2001 proposals is August 31, 2001; recipients of this year's awards will be announced on October 8.