We would like to congratulate Morgan et al.1 for their important study on the phase of retinal vein pulsations in relation to intracranial pressure. They found a difference in the phasing of the intraocular pressure (IOP) curve and that of the intracranial pressure (ICP) curve with respect to the cardiac cycle, with the ICP curve reaching its height earlier than the IOP curve. They also found that the collapse of the central retinal vein occurred at the time of the minimum of the ICP and IOP (i.e., at the time of the diastole), while the maximal retinal vein diameter was measured at a mean of 2% of the cardiac cycle before the IOP maxima and at a mean of 21% after the ICP maxima. Morgan et al. concluded that the central retinal vein collapse was not induced by the intraocular systole, but that the ICP pulse dominated the timing of venous pulsation.