Retinal Venous Pulsation
Venous pulsation is evident in the normal retina when observed with an ophthalmoscope, particularly at the margin of the disc. It is sometimes difficult to see, and may be more obvious in the recumbent position (because of higher pressure within the retinal veins). Venous pulsation is lost when intracranial pressure rises above venous pressure. This is a sensitive marker of raised intracranial pressure, and may be an early sign of impending papilledema; however, venous pulsation may also be absent in pseudopapilledema, and sometimes in normal individuals.
Jacks AS, Miller NR. Spontaneous retinal venous pulsation: etiology and significance. Journal of Neurology, Neurosurgery and Psychiatry2003; 74: 7-9