[The ocular pulse].

The ocular pulse SIR,-The important editorial on the ocular pulse,' highlights the observations of the retinal arterial pulsations noted by early ophthalmologists. It was Thiel' who first attempted to quantify the recording of the transmitted pulsations which had become known as the tonometric sign as early as 1879. Priestley Smith' had clearly described the spontaneous vascular pulsations observed during tonometry. This was reinforced by the observations of Schi0tz and became an important observation for those undertaking tonometry up to the time of the applanation method. The earliest precise recording of the ocular pulse was that of Thiel in 1928.2 Subsequently Maurice4 used a recording tonometer, to be followed by Castren and Lavikanen,' who adapted a Muller electrotonometer. Following the work of Suzuki' a number of groups developed a system of recording the ocular pulse using a fluid filled suction cup system. The piezoelectric system of Bynke7 seems to be the least 'invasive' and most precise. The methods ofWalker et aPl and Perkins9 were later developments. In spite of the variety of approaches the amplitude and variation in pulse pressures correlate quite closely. Both in time and form the pulse wave does not correspond with a typical arterial pulsation. It lacks the dicrotic notch which is the characteristic of an arterial pulse, and when placed in time sequence in relation to the R-wave of the ECG, or the Doppler pulse wave recruited from an adjacent orbital vessel, for example, the supra-trochlear vessel, its time relationship is closer to the middle of diastole. The only report which demonstrates a dicrotic notch is that of Barnes and co-workers,"° who applied the pulse sensor, externally, through the lids, and it is believed that this was recording ophthalmic artery pressure pulsations and not an ocular pulse. While evidence to link the ocular pulse amplitude to either C or PO/C is lacking, there is a significant amount of evidence from all studies that it has a direct relationship with levels of ipsilateral carotid perfusion. The consequence of this is to question the role of a topical 0-blocker which does not contain intrinsic sympathomimetic activity (ISA). 9 Perkins ES. The ocular pulse and intraocular pressure as a screening test for carotid artery stenosis. This book is written by a professor of plastic surgery who specialised in eyelid surgery. It is of interest to the ophthalmologist, as it minutely examines the normal appearance of the eyelids and the …