Abstract
Purpose :
In earlier comparative studies the mean central retinal vein pressure (CRVP) was higher than the mean intraocular pressure (IOP) in patients with primary open angle glaucoma (POWG) and has been identified as a potent risk factor. The purpose of this study was the measurement of the CRVP in unselected patients with primary open angle glaucoma and the comparison of its distribution with that of the IOP.
Methods :
Study type: prospective cross-sectional. Subjects were 50 unselected patients with POAG defined according the guidelines of the European Glaucoma Society who underwent intraocular pressure (IOP) diurnal curve measurement under medication. Age: 69±8years. M/F:24/26. BMI:25.8±3.5. The more affected eye was included. Measurement of CRVP: Contactlens dynamometry (CLD) (Imedos, Jena, Germany). IOP measurement before CLD : Dynamic contour tonometry (Ziemer, Port, Switzerland. Two formulas were used for the calculation of the retinal perfusion pressure (RPP): Mean arterial pressure in the ophthalmic artery minus IOP or minus CRVP.
Results :
Pressure unit: mmHg. Systemic blood pressure: 158±23/90±12. IOP under medication:15.9±2.8. There is no IOP value above 30 mmHg (fig 1). CRVP:21.3±9.7. CRVP was significantly higher than the IOP (p=0.00045, paired t-test). Nine CRVP values were above 30mmHg (fig.1).When the retinal perfusion pressure was calculated inserting the IOP in the formula RPP was 59±9mmHg. There was no value below 40mmHg (fig.2). With CRVP inserted in the formula RPP was 54±14mmHg and 8 of the 50 patients showed a RPP below 40mmHg (fig.2).
Conclusions :
In this cross sectional study the the mean CRVP was higher than the IOP by 5.4 mmHg. This difference is statistically highly significant and confirms earlier results. The distribution of the pressure values shows a clearly different pattern. Inserting the IOP in the formula for the perfusion pressure all RPPs were above 40 mmHg. When the CRVP was inserted in the formula the RPP in 8 of our 50 patients showed values below 40 mmHg. It may be concluded that the calculation of the RPP by using the CRVP may more clearly identify single patients at risk.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.