科研之友
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摘要
Background: The ocular perfusion pressure (PP) is presently calculated by subtracting the intraocular pressure (IOP) from the mean ophthalmic artery pressure. In recent years papers have been published in which it has been shown that the pressure in the central retinal vein (CRV) may be higher than the IOP in half the glaucoma patients resulting in a lower perfusion pressure in the retina and in the prelaminar layer of the optic nerve head. Objectives: A review of these papers is given in which the pulsation of the CRV was assessed or in which the pressure in the CRV has been measured on comparing glaucoma patients and control subjects. Materials and Methods: By using the Starling resistor as a model the origin of the pulsation of the CRV is explained. The term ophthalmodynamometric force used by Morgan et al. is shown as being the IOP increment given in units of gram-force which may be converted to 0.82 mmHg. Contact lens dynamometry is described. Results: In the five studies published until now the pulsation of the central retinal vein was absent in about half of the glaucoma patients. That is the sign that the pressure in the CRV was higher than the IOP. A worse mean deviation has been found to be strongly predictive of a higher pressure in the CRV. Higher pressures in upper and lower hemiveins were strongly associated with a worse mean deviation in the corresponding hemifields. In the two studies in which the CRV pressure has been measured in mmHg it was up to 25 mmHg higher in the median than the IOP. A Long-term study of 82 months has shown that the pressure in the central retinal vein is strongly predictive of an increase of optic disc excavation. Conclusions: The CRV pressure is often higher in glaucoma patients resulting in a lower PP than assumed until now.
- 出版日期2015-2
