Is the pulsating vascular tree entoptic phenomenon an indicator of ophthalmic artery pressure?

The relation between the intraocular pressure (IOP) at which the pulsating vascular tree (PVT) entoptic phenomenon is first observed and the ophthalmic artery diastolic pressure measured by ophthalmoscopic examination of the central retinal artery was determined in 25 normal volunteers. The PVT entoptic phenomenon consists in perceiving black stripes in the shape of branches of a tree appearing and disappearing synchronously with each heartbeat when the intraocular pressure is increased. The average IOP at which the entoptic phenomenon was first observed was 51.4 +/- 7.5 mm Hg, and the average ophthalmic artery diastolic pressure was 51.8 +/- 7.5. The correlation coefficient between both sets of numbers was r = 0.97 (p less than 0.01). These results show that the ophthalmic artery diastolic pressure can be measured accurately with the perception of the PVT phenomenon as an end point. Because the perception of the phenomenon is not disturbed by ocular media opacities, this method enables the determination of the ophthalmic artery diastolic pressure in eyes where an ophthalmoscopic examination is not possible.