Eyeworld

FEB 2012

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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February 2011 February 2012 EW GLAUCOMA 89 of injections were 28.3 versus 13.9, she said. This finding also confirmed the results of the group's prior study with the cohort of 349 patients. In that analysis, in addition to the total number of injections, other signifi- cant predictors of IOP elevation in- cluded pre-existing glaucoma, prior history of intravitreal steroid ther- apy, history of IOP elevation related to steroid therapy, prior eye surgery other than cataract extraction, and prior posterior capsulotomy. The total number of anti-VEGF injec- tions remained a significant predic- tor of IOP elevation even after controlling for the other potential confounding factors, she said. Why does IOP rise? Malik Y. Kahook, M.D., associate professor, ophthalmology depart- ment, University of Colorado, Aurora, has conducted research into the potential causes of IOP ele- vations associated with anti-VEGF therapy. "The cause of IOP spikes is likely multifactorial. Silicone oil and other contaminants that are caused by the repackaging of Avastin [beva- cizumab, Genentech] or the han- dling of Lucentis could be the cause in some patients," he said. "Silicone oil leaches from the syringe and rubber stopper when repackaged for an extended period of time, when freeze/thaw cycles occur, and during shock from shipping as well as expo- sure to light. Contaminants can also occur from the filter used with the Avastin product. Single or repeated injections of these tiny particles can potentially clog the outflow system and lead to spikes in IOP that are re- sistant to medications and laser treatment." He added, "This would also ex- plain why reported cases have oc- curred in clusters and why the phenomenon is not more common. Alternatively, there could be a direct effect by the anti-VEGF agent on the outflow system of the eye, making it less porous to fluid by virtue of its effects on cell junctions. This is not consistent with the relatively few number of cases reported and has not been validated beyond the theo- retical level." This phenomenon has implica- tions for patients. "Doctors should check IOP before and then 20-30 minutes after injections and should be more vigilant in patients with pre-existing glaucoma," he advised. EW Editors' note: Drs. Freund and Kahook have no financial interests related to this article. Contact information Freund: kbfnyf@aol.com Kahook: malik.kahook@gmail.com

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