Altitudinal visual field asymmetry is coupled with altered retinal circulation in patients with normal pressure glaucoma.

AIM To compare the effect of altitudinal asymmetric glaucomatous damage on retinal microcirculation in patients with normal pressure glaucoma (NPG). METHODS In a prospective cross sectional study patients with NPG (washed out for antiglaucomatous therapy) and altitudinal asymmetric perimetric findings between the superior and inferior hemisphere (Humphrey 24-2) (n=18) were included and compared with 20 NPG patients with symmetrical field defects and 18 healthy subjects. Fluorescein angiograms were performed using a scanning laser ophthalmoscope. Using digital image analysis, arteriovenous passage time (AVP) and vessel diameters were assessed for comparison of corresponding affected and less affected temporal arcades. RESULTS Both affected and less affected hemispheres showed significantly prolonged AVP times (p<0.001) when compared with healthy subject data. In hemispheres with more severe glaucomatous field loss the AVP times were significantly (p=0.04) prolonged compared with the less affected hemisphere (AVP affected 3.1 (SD 7) seconds v AVP less affected 2.61 (1.4) seconds). There was no asymmetry effect on arterial and venous diameter measurements. CONCLUSION Altitudinal visual field defects are linked together with circulatory deficits of the retinal tissue. The attenuated circulation seems to be a considerable factor in the natural course of glaucomatous optic neuropathy.