Abstract
Purpose: :
Ocular blood flow dysregulation has been implicated in the pathogenesis of glaucoma. In addition, a recent study also indicated that the disease may be associated with altered retinal oxygenation, although the authors speculated that this may be a result of the atrophic changes in glaucoma, because a strong correlation with the stage of the disease was observed. In the present study we tried to get more insight into this question by studying the response of optic nerve head blood flow to 100% oxygen breathing.
Methods: :
In the present study 32 patients with primary open angle glaucoma and 32 healthy control subjects were included. Optic nerve head blood flow (ONHBF) was measured using laser Doppler flowmetry at baseline and during a 20 minutes oxygen breathing period. In addition, endothelin plasma levels were measured at baseline as well as during oxygen breathing.
Results: :
100% oxygen breathing did not alter blood pressure or pulse rate but induced a pronounced increase in arterial oxygen tension (p < 0.001 versus baseline, p = 0.341 between groups). As expected this hyperoxia was associated with a reduction of ONHBF in both groups (p < 0.001 versus baseline). This reduction was, however, more pronounced in healthy subjects (-27 ± 7%) than in patients with primary open angle glaucoma (-17 ± 6%, p = 0.031 between groups). Whereas 100% oxygen breathing increased endothelin plasma levels in both groups no difference was found between groups (p = 0.621).
Conclusions: :
The present study indicates that patients with primary open angle glaucoma have reduced ONHBF response to 100% oxygen breathing.
Keywords: oxygen • optic nerve