Relationship of Spontaneous Retinal Vein Pulsation with Ocular Circulatory Cycle

PurposeTo determine the timing of spontaneous venous pulsation (SVP) relative to the ocular circulatory cycle by using the movie tool of confocal scanning laser ophthalmoloscope.MethodsA 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 (CRAmax and CRAmin, respectively) and CRV (CRVmax and CRVmin, respectively) was identified during four pulse cycles. The interval between CRVmin and CRAmin, and between CRVmax and CRAmax was expressed as the number of frames and as a percentage of the ocular circulatory cycle.ResultsThe ocular circulatory cycle (from one CRAmax 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). CRVmax occurred 1.0±0.2 frames after CRAmax (equivalent to 13.0% of the ocular circulatory cycle), while CRVmin occurred 1.1±0.4 frames after CRAmin (equivalent to 14.6% of the ocular circulatory cycle).ConclusionsDuring 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.