Glaucoma patients demonstrate faulty autoregulation of ocular blood flow during posture change

Background/aims-Autoregulation of blood flow during posture change is impor tant to ensure consistent organ circulation. The purpose of this study was to compare the change in retrobulbar ocular blood flow in glaucoma patients with normal subjects during supine and upright posture. Methods-20 open angle glaucoma patients and 20 normal subjects, similar in age and sex distribution, were evaluated. Blood pressure, intraocular press ure, and retrobulbar blood velocity were tested after 30 minutes of sitting and again after 30 minutes of lying. Retrobulbar haemodynamic measures of peak systolic velocity (PSV), end diastolic velocity (EDV), and resistance index (RI) were obtained in the ophthalmic and central retinal arteries usi ng colour Doppler imaging (CDI). Results-When changing from the upright to supine posture, normal subjects d emonstrated a significant increase in OA EDV (p = 0.016) and significant de crease in OA RI (p = 0.0006) and CRA RI (p = 0.016). Glaucoma patients demo nstrated similar changes in OA measures of EDV (p = 0.02) and RI (p = 0.04) , but no change in CRA measures. Conclusion-Glaucoma patients exhibit faulty autoregulation of central retin al artery blood flow during posture change.