The Effects of Darkness on Retrobulbar Hemodynamics in Patients with Early Stages Retinitis Pigmentosa

Abstract

To investigate the retrobulbar hemodynamic changes occurring in light and darkness in patients with early stages retinitis pigmentosa (RP). Eleven early stages RP patients were enrolled in the study. The peak systolic velocity (PSV), end-diastolic velocity (EDV), pulsatility index (PI) and resistivity index (RI) of the ophthalmic artery (OA) and central retinal artery (CRA) were measured by color Doppler imaging in light and darkness. The results were compared with that of 10 age-matched normal subjects. PSV and EDV of the OA did not show significant differences in both groups. However, PSV and EDV of the CRA in RP patients decreased significantly in darkness (p = 0.001, p < 0.001, respectively). In addition, we found a significant increase in RI of the CRA in RP patients in darkness (p = 0.003). On the contrary, PSV and EDV of the CRA in control subjects showed a significant increase (p = 0.002, p < 0.001, respectively) and RI showed a significant decrease in darkness (p = 0.004). Darkness causes a decreased blood flow in the CRA in early stages of RP.