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Purpose  To determine the timing of spontaneous venous pulsation (SVP) relative to the ocular circulatory cycle by using the movie tool of confocal scanning laser ophthalmoloscope.    Methods  A video recording of the fundus was obtained using a confocal scanning laser ophthalmoscope (Spectralis HRA, Heidelberg Engineering, Heidelberg, Germany) at 8 frames/s in 47 eyes (15 glaucoma patients and 32 glaucoma suspects) with visible pulsation of both the central retinal artery (CRA) and vein (CRV). The timing of the maximum and minimum diameters of the CRA (CRA max  and CRA min , respectively) and CRV (CRV max  and CRV min , respectively) was identified during four pulse cycles. The interval between CRV min  and CRA min , and between CRV max  and CRA max  was expressed as the number of frames and as a percentage of the ocular circulatory cycle.    Results  The ocular circulatory cycle (from one CRA max  to the next) lasted 7.7±1.0 frames (958.8±127.2 ms, mean±SD), with a mean pulse rate of 62.6 beats/min. The diameter of the CRA was increased for 2.4±0.5 frames (301.9±58.8 ms) and decreased for 5.3±0.9 frames (656.9±113.5 ms). CRV max  occurred 1.0±0.2 frames after CRA max  (equivalent to 13.0% of the ocular circulatory cycle), while CRV min  occurred 1.1±0.4 frames after CRA min  (equivalent to 14.6% of the ocular circulatory cycle).    Conclusions  During SVP, the diameter of the CRV began to decrease at early diastole, and the reduction persisted until early systole. This finding supports that CRV collapse occurs during ocular diastole.

Relationship of Spontaneous Retinal Vein Pulsation with Ocular Circulatory Cycle