Eyeworld

EW GLAUCOMA 110 February 2011 March 2011 forgetting to take the prophylactic acetazolamide," he said. He does not think that having open angles is a true risk factor for an IOP spike. Rather, he said, the pa- tients with narrow angles tended to have lower IOP after surgery, which made having open angles look like a relative risk factor. The use of acrylic lenses was of interest, he said. "Increased IOP fol- lowing implantation of acrylic lenses has been reported in one of the two studies that looked at this issue," he said. "There have been a few hypotheses as to the cause of this, including the higher likelihood of retained viscoelastic due to adhe- sion to the hydrophilic acrylic lenses, or perhaps even direct effects on the ciliary body's production of aqueous. We are not aware of a de- finitive reason to explain this phe- nomenon, although the difference warrants further investigation." Several potential risk factors turned out not to be important in identifying the patients who had IOP spikes, said Dr. Chen. These in- cluded age, pre-op IOP, the number of IOP-lowering medications used, the need for intra-op iris manipula- tion, and whether or not the wound was sutured closed. Preventing IOP spikes Given this new data, has Dr. Chen changed his approach to managing IOP in his glaucoma patients under- going cataract surgery? "We are becoming more aggres- sive on this issue," he said. "Our first step is to underscore the importance of taking the post-operative dose of acetazolamide. While 21% of pa- tients spiked overall, five of the eight patients who didn't take their acetazolamide had an IOP spike. That's 63%. Clearly the acetazo- lamide helps, so we've been strongly encouraging patients to take it after surgery." He is also revisiting the practice of holding routine IOP medications on the morning of surgery. "Perhaps we should provide sterile bottles in the pre-operative area and dose our glaucoma patients with their typical morning drops be- fore surgery," he said. Dr. Fechtner agreed that preven- tion is the best approach to post-op IOP spikes. "Once the damage is done, it's done," he said. He found Dr. Chen's results regarding acetazo- lamide encouraging. "It's good to know that a single dose of acetazo- lamide given post-operatively can re- duce the rate of IOP spikes from over 60% to less than 20%. It makes sense to remember to offer this pro- tection from IOP spikes, especially for those with more advanced dis- ease." EW Editors' note: Drs. Chen and Fechtner have no financial interests related to their comments. Contact information Chen: pchen@uw.edu Fechtner: fechtner@umdnj.edu Predicting continued from page 109 New minimally invasive procedure found safe and effective for glaucoma treatment A new minimally invasive surgical technique called sclerothalamo- tomy ab interno (STT ab interno) lowers IOP in primary open- angle and juvenile glaucoma and is safe and effective, according to a Swiss study published in the February issue of the Journal of Glaucoma. Researchers reported the 6-year follow-up results from the trabecular surgery, which, for this study, was performed between February and July 2002 in 58 eyes of 58 patients who were diagnosed with open-angle glau- coma and five patients who had juvenile glaucoma. During the procedure, a custom-made, high-frequency dissection probe (19-gauge with a tip of 0.3×1 mm) applies a bipolar current of 500 kHz frequency while probing about 1 mm into the nasal sclera (ab in- terno) and through the trabecular meshwork and Schlemm's canal. The probe then reportedly forms a deep sclerotomy that is 0.3 mm high and 0.6 mm wide. During the follow-up, researchers found that baseline IOP was 25.6±2.3 mm Hg for the open-angle glaucoma group and 39.6±2.3 mm Hg for the juvenile glaucoma group. The mean IOP for the 72-month pe- riod was 14.7±1.8 mm Hg for the open-angle glaucoma group and 13.2±1.3 mm Hg for the juvenile group. "The IOP after surgery was statistically significantly lower than the baseline IOP at all measured intervals (P<0.001)," the report said. "After 72 months, only 11 eyes accounted for a 20.8% continuous antiglau- coma therapy. With regard to the procedure no serious complication was documented."

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