IOPstim
System for modulation of intraocular pressure
At Imedos, we recognized the important role of increased retinal venous pressure in the development of eye diseases early on with our own product line for ophthalmodynamometry.
An innovative device for ophthalmodynamometry
- Determination of increased retinal venous pressure
- Stimulation or provocation of the microcirculation for functional diagnosis of the autoregulation of the retinal vessels.
Increased retinal venous pressure is a clinically relevant factor in half of all glaucoma patients
The prevailing clinical view that retinal venous pressure is equivalent to intraocular pressure is refuted by the current state of science. Especially in glaucoma patients, but also in patients with vascular occlusion or diabetic retinopathy, it has been shown that compared to intraocular pressure, elevated retinal venous pressure is clinically relevant. Until now, retinal venous pressure was largely ignored in diagnosis because no suitable measurement technology was available.
Further reading:
Modulation of Human Intraocular Pressure Using a Pneumatic System
- Gentle modulation of intraocular pressure with free pupil
- Gentle lateral pressure on the eye at the lid angle without direct corneal contact
- Very good tolerability by patients
- No anesthesia required at the balloon contact area on the eye
- Simple determination of retinal venous pressure using an external tonometer
- No calibration (scaling) of the system required
- Simple, intuitive control via haptic pushbuttons and foot switches
Ophthalmodynamometry / determination of increased retinal venous pressure (RVP)
RVP is an important retinal blood flow parameter. An elevated RVP is considered to be 
a risk factor for numerous eye diseases, such as glaucoma, retinal vascular occlusion and diabetic retinopathy.
“One-third of all glaucoma patients have a retinal venous pressure that is higher than intraocular pressure. As a result, blood flow to the retina and optic nerve fibers is more impaired than previously thought.”
2017, Prof. Dr. med. R. Stodtmeister, Department of Ophthalmology, University Hospital Carl Gustav Carus in Dresden, Germany
Video – RVP measurement
To clarify the need for retinal venous pressure testing using IOPstim, the first step is to look for spontaneous venous pulsations in the optic nerve papilla area by optical examination of the retina using a slit lamp or fundus camera. If these are visible, then the retinal venous pressure corresponds to the intraocular pressure (IOP). If no spontaneous venous pulsation is visible, measurement of the retinal venous pressure is recommended, because in this case it is higher than the intraocular pressure and thus influences the blood flow to the eye in its place.
The IOPstim allows a simple, painless and gentle increase of the intraocular pressure:
- Positioning and adjustment of the IOPstim
- While observing the venous vessels in the optic disc region: slowly inflate the balloons in the eyelid angle of the eye to increase the IOP.
- As soon as a spontaneous vein pulse is visible on the papilla (visual criterion): stop the pressure increase at the IOPstim; the IOP is kept constant
- This currently elevated IOP corresponds to the value of the retinal venous pressure, which can now be measured with an external tonometer
- After tonometer measurement: Slowly lower the pressure in the balloon to lower the IOP and relieve the eye.
In addition to ophthalmodynamometry, the IOPstim can also be used to study the autoregulation of the retinal vessels. Intact autoregulation of these vessels is essential for microcirculation in the tissues of the eye. In case of dysregulation due to diseases or physical overload reactions, systemic disturbances of the microcirculation occur, which are accompanied by an undersupply of numerous tissues in the body.
The severity of this dysregulation is in many cases an important risk factor and prognostic indicator especially for vascular retinal diseases and their progression, e.g. glaucoma, diabetic retinopathy and vascular occlusions.
For functional diagnostics of autoregulation with the IOPstim, the intraocular pressure is first measured as described in the section Ophthalmodynamometry and the blood flow to the retina is thus disturbed for a short time. With our Imedos Dynamic Analyzer (with “research option”), the vascular response of the large retinal vessels or also of the capillaries is recorded in parallel to this pressure increase. It describes the robustness of the autoregulation against perfusion pressure disturbances and allows quantification of a dysregulation of the vascular response.
Reference literature on retinal vein pressure (RVP)
1. Cybulska-Heinrich et al. Patients with diabetic retinopathy have high retinal venous pressure. The EPMA Journal (2015) 6:5 doi:10.1186/s13167-015-0027-1
2. Flammer and Konieczka. Retinal venous pressure: the role of endothelin. The EPMA Journal (2015) 6:21 doi:10.1186/s13167-015-0043-1
3. Kim KE, Kim DM, Flammer J, Kim KN (2015) Central Retinal Venous Pressure in Eyes of Normal-Tension Glaucoma Patients with Optic Disc Hemorrhage. PLoS ONE 10(5): e0127920. doi:10.1371/journal.pone.0127920
4. Lei Fang, Michael Baertschi, and Maneli Mozaffarieh. The effect of flammer- syndrome on retinal venous pressure. BMC Ophthalmol. 2014; 14(1): 121. Published online Oct 13, 2014. doi:10.1186/1471-2415-14-121 PMCID: PMC4216361
5. Vahedian et al. Retinal venous pressure in chronic smokers. The EPMA Journal (2015) 6:8 doi:10.1186/s13167-015-0031-5
6. Pillunat KR et al.Central retinal venous pulsation pressure in different stages of primary open-angle glaucoma. Br J Ophthalmol 2014;98:1374-1378 doi:10.1136/bjophthalmol-2014-305126
7. Stodtmeister R, Ventzke S, Spoerl E, et al. Enhanced pressure in the central retinal vein decreases the perfusion pressure in the prelaminar region of the optic nerve head. Invest Ophthalmol Vis Sci. 2013;54:4698-4704. doi:10.1167/iovs.12-10607
8. Mozaffarieh M, Bärtschi M, Henrich PB, Schoetzau A, Flammer J. Retinal venous pressure in the non-affected eye of patients with retinal vein occlusions. Graefes Arch Clin Exp Ophthalmol. 2014 Oct;252(10):1569-71. doi: 10.1007/s00417-014-2617-3. Epub 2014 Mar 28.
9. Fang L, Turtschi S, Mozaffarieh M. The effect of nifedipine on retinal venous pressure of glaucoma patients with the Flammer-Syndrome. Graefes Arch Clin Exp Ophthalmol. 2015 Jun;253(6):935-9.doi:10.1007/s00417-015-3001-7. Epub 2015 Apr 12.
