Choroidal neovascularization after globe penetration by peribulbar anesthesia.

standard assays for such antibodies, no standardized criteria for distinguishing positive from negative results, and no data on sensitivity and specificity of these assays based on clinical criteria for a causal relationship. Although causality assessment methods in pharmacology remain a matter of debate, in our patient acetazolamide caused pure and severe thrombocytopenia with “certain” evidence according to the World Health Organization system of causation of a drug reaction, with “very likely” evidence according to the French standardized methodology, and with the highest level of evidence (“definite”) according to standardized criteria recently developed by Rizvi et al (database available at http://moon.ouhsc.edu /jgeorge). Such high levels of evidence for the causal relationship of acetazolamide to thrombocytopenia have never been reported until now, to our knowledge. Discovery of isolated thrombocytopenia in a patient who is taking several medications also presents a challenging clinical problem. The principal interest of the level of evidence is to help clinical decision making about which drugs may more likely be implicated as a cause of thrombocytopenia and therefore should be discontinued as quickly as possible. Acetazolamide should be considered a definite thrombocytopeniainducing agent. Potential consequences of thrombocytopenia seem to be limited when the drug is prescribed for a few days, whereas it appears different with much longer treatment. In that case, regular complete blood cell count, especially in the presence of bleeding, should be recommended.