Factors influencing the ocular pulse--axial length.

The amplitude of the intraocular pressure pulse and pulsatile ocular blood flow (POBF) were correlated with the axial length and refraction of 68 eyes of healthy subjects. Measurements were obtained with subjects in the sitting position using an ophthalmic A-scan and a pneumotonometer linked to a Langham ocular blood-flow system. The amplitude of the ocular pulse and the magnitude of POBF were found to decrease with increasing axial length (r = -0.61, P less than 0.001 and r = -0.74, P less than 0.001, respectively). A similar close relationship was found between the ocular pulse amplitude and POBF and the refractive state of the eye (r = 0.63, P less than 0.001 and r = 0.7, P less than 0.001, respectively). The reasons for the association are discussed and the importance of the observations in the construction of studies in which ocular pulse amplitude or POBF are to be measured in different groups of subjects is emphasised.