Abstract
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.
Highlights
Spontaneous retinal pulsation (SVP) manifests as a rhythmic variation in the caliber of the retinal vein near to or on the optic disc, and is visible in approximately 80–90% of healthy individuals [1,2,3]
It is generally considered that the absence of spontaneous venous pulsation (SVP) in glaucoma is likely due to increased resistance of the retrolaminar central retinal vein (CRV) [1,6,7,8,9].the frequent absence of SVP in glaucoma patients may support that vascular factors play a role in the pathogenesis of glaucomatous optic neuropathy [4]
When SVP was first described by Coccius [10], it was considered that the venous collapse was induced by an elevation in intraocular pressure (IOP) secondary to blood influx to the eye during systole
Summary
Spontaneous retinal pulsation (SVP) manifests as a rhythmic variation in the caliber of the retinal vein near to or on the optic disc, and is visible in approximately 80–90% of healthy individuals [1,2,3]. Levine [13] questioned this concept based on the findings that the retinal venous pressure is always higher than the IOP [14,15,16], and that the IOP is instantly transmitted to the retinal veins [15] He suggested that the greater fluctuation of IOP compared to that of the retrolaminar venous pressure plays a major role in SVP [13]. This theory is based on the assumption that the venous collapse occurs at ocular systole
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