The findings suggest that IL-6 and IL-8 may be involved in the pathogenesis of PDR, PVR, and traumatic PVR. High proportions of RPE cells and macrophages are associated with elevated IL-6 and IL-8 levels in the vitreous of PDR and PVR patients; however, the fact that these cells are not predominant in traumatic PVR suggests that different immune response mechanisms may be active in the pathogenesis of these disorders.

The aim of the present study was to assess and to compare the orbital and retinal vascular flow dynamics and resistance in patients with homozygous sickle cell disease with controls by means of duplex and color Doppler ultrasonography. Forty-six patients with homozygous sickle cell disease (SCD) and 20 healthy subjects were included in the study. None of the patients had objective signs of ocular involvement. Duplex and color Doppler ultrasonography of the ophthalmic, short posterior ciliary, and central retinal arterial flows of the both eyes were performed to assess peak systolic flow velocity (PSFV), end-diastolic flow velocity (EDFV), and mean flow velocity (MFV) through entire cardiac cycle with further calculation of resistive indices (RI) and pulsatility indices (PI). Ophthalmic arterial flow velocities were significantly increased in patients with SCD than in controls (P < 0.0001). Blood flow velocities of the central retinal artery were found to be significantly reduced (P < 0.0001) while RI and PI values were markedly higher (P < 0.02 and P < 0.03) in patients with SCD compared to controls. Reduction of retinal vascular flow velocities and increase of retinal vascular resistance were significantly related to the mean hemoglobin and hematocrit levels, red blood cell count, and mean corpuscular hemoglobin volume (P < 0.009, P < 0.01, P < 0.02, and P < 0.04, respectively). In conclusion, Doppler ultrasonography in patients with SCD who had no objective signs of ocular involvement allowed detection enhancement of ophthalmic flow velocities, reduced retinal flow velocities, and increased retinal vascular resistance, which are associated with haematological features. Am.