Intraocular Pressure & Functional Diagnostics of Autoregulation

Imedos has recognised the importance of an increased retinal venous pressure for eye diseases such as glaucoma at a very early stage. Up until the middle of 2019 we offered our customers the Löw contact lens dynamometer, which allowed to register an increased retinal venous pressure.

However, today, we offer an even better alternative: the IOPstim, an innovative device for:

  • Determination of an increased retinal venous pressure (RVP) within the scope of ophthalmodynamometry
  • Stimulation or provocation of the retinal microcirculation for the functional diagnostics of autoregulation

Features & benefits

  • Scope of delivery: Base unit including foot switch, plug-in power supply unit, glasses frame and 50 stimulation balloons
  • Simple, intuitive control via five buttons on the front of the base unit and a dual foot switch
  • Gentle modification of the intraocular pressure (IOP) with free pupil
  • Gentle lateral pressure on the eye in the palpebral angle without direct corneal contact
  • Very good patient tolerability
  • No anaesthesia required at the balloon contact area of the eye
  • Simple determination of the RVP using an external tonometer
  • No calibration (scaling) of the IOPstim required

Ophthalmodynamometry: IOPstim for determining an increased RVP

RVP is an important blood flow parameter of the retina. Increased RVP is considered a risk factor for many eye diseases, including glaucoma, retinal vascular occlusion and diabetic retinopathy.

»One third of all glaucoma patients have a retinal venous pressure that is higher than the intraocular pressure. As a result, the blood supply to the retina and optic disc fibres is more severely impaired than previously assumed.«

2017, Prof. Dr. med. R. Stodtmeister, Eye Clinic at the Carl Gustav Carus University Hospital in Dresden

Testing principle

First, the spontaneous venous pulse is searched for on the papilla. If the spontaneous pulse is visible, the retinal venous pressure (RVP) corresponds to the intraocular pressure (IOP). In this case, the IOP determines the perfusion pressure and the blood flow in the eye.

If no spontaneous venous pulse is visible, it is recommended to measure the RVP. In this case, the RVP is higher than the IOP and determines the blood circulation of the eye instead of the IOP.

The IOPstim enables a simple, painless and gentle increase of the IOP:

  • Positioning and adjustment of the IOPstim
  • While observing the papilla: Slowly inflating the balloon in the palpebral angle of the eye to increase the IOP
  • As soon as the spontaneous venous pulse is visible on the papilla (visual criterion): Stop increasing the pressure and keep the increased IOP constant
  • The increased IOP corresponds to the value of the RVP and can be measured using an external tonometer
  • After successful measurement: Deflating the balloon pressure slowly to reduce the IOP and relieve the eye

Functional diagnostics of autoregulation

The IOPstim can also be used to study the function of retinal autoregulation. An intact autoregulation keeps microcirculation healthy. However, if the autoregulation is overstrained or disturbed, i. e. a so-called dysregulation is present, microcirculation is interrupted.

In many cases, the severity of a dysregulation is an important risk factor and prognosis indicator for vascular retinal diseases and their progression, e.g. glaucoma, diabetic retinopathy and vascular occlusion.

Functional principle

For the functional diagnostics of autoregulation using the IOPstim, the intraocular pressure (IOP) is first increased, meaning that blood flow to the retina is temporarily interrupted.

With the DVA 3.0, the vascular response of the large retinal vessels or even the capillaries can be recorded parallel to this pressure increase.

The vascular response describes the function of autoregulation against perfusion pressure disorders and allows a dysfunction to be determined, including its severity.

Please feel free to contact us for further information!