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Siegfried et al. (1233) measured PO2 distribution, with an optical oxygen sensor, in the anterior segments of patients undergoing cataract and/or trabeculectomy. They compared PO2 values in 19 African Americans' eyes with similar measurements taken from 53 Caucasian eyes. The major finding was that African Americans had significantly higher PO2 values than Caucasians and that the PO2 beneath the central cornea increased with increasing age irrespective of racial origin. Although potentially interesting, significant differences were also reported between the two groups in other parameters, including older age and reduced central corneal thickness in the African Americans. The authors go on to suggest that this increase in observed PO2 reflects underlying differences in oxygen use in the cornea and lens of African Americans. They also proposed that the increase in PO2 could promote oxidative stress in the outflow pathways and provide a mechanism for the increased rates of ocular hypertension and open-angle glaucoma observed in African Americans. This is an interesting hypothesis and we look forward to further studies that provide supporting evidence.