2017 - 2 Issue

Original article

Intracranial Pressure Evaluation by Ophthalmologist

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The value of ICT is important in diagnosis of the diseases of the eye and orbit Methods for direct measurement of intracranial pressure (ICT) are exact, but they are invasive and there is some risk of infection and damage of the tissue. Currently there are 2 valid indirect methods of mesurement of IKT. Digital Ophthalmodynamometry (D-ODM) and Transcranial Doppler ultrasonography (TDU). D-ODM is a non-invasive method for measuring of the Pulsating Venous Pressure (VPT). We can measure VPT by the pulse phenomena. Physiologically (to be maintained blood flow) VPT not be less than the ICT and intraorbital pressure (IorbitT). If we raise the VPT to compensate the current IKT (or IorbitT) - there is a pulsation VCR. We can calculate aproxymative IKT with the formula: IKT = 0.903 - (VPT) - 8.87, or IKT = 0.29 + 0.74 (VOT / PI (AO)). [VOT = intraocular pressure. PI – pulsatility index arteriae ophthalmic from Color Doppler ultrasonography.] IKT can be approximate calculate with mathematical formulas: IKT = 0:55 × BMI (kg / m2) + 0.16 × KTD (mmHg) - 0:18 x age (years) - 1.91. [KTD - diastolic blood pressure, BMI - Body master index] or: IKT = 16.95 x 0.39 x OSASW09 + BMI + 0.14 + TKS - 20.90. [OSASW095: width of the orbital arachnoid space at a distance of 9 mm behind the eyeball (nuclear magnetic resonance). BMI: Body Mass Index. TKS: mean arterial pressure]. Normal values of VPT are under 15 torr. The risk of increased intracranial pressure is above 20 torr. Under physiological conditions, there is intraocular pressure lower in about 5 torr than VPT.
Conclusion: D-ODM is a useful screening method in the evaluation of IKT for hydrocephalus, brain tumors, cerebral hemorrhage after brain trauma and also in ocular diseases: Glaucoma, Ocular hypertension, orbitopathy (endocrine orbitopathy), ischemic / non-ischemic occlusion of blood vessels of the eye, indirect detection ICT carotid artery-cavernous fistula, amaurosis fugax, optic neuropathy. D-ODM is suitable for immediate evaluation of IKT, but is not suitable for continuous monitoring. As it can be repeated, it is useful for a patient suspected of having an increased ICT.