Analysis of Retinal Vessel Analyzer (RVA) recordings of retinal vessel pulsations, and putting them in context of intraocular pressure (IOP) pulsations by means of electrocardiographic (ECG) gating, in order to determine the lead source for pulsations of retinal veins.

Rationale / Objective is to construct the retinal vessels wall pulsation cycle using an electrocardiographic gating, and to analyse it in comparison with an analogue intraocular pressure (IOP) cycle.

Based on the amplitude and on the phase shift of pulsations of retinal vessel wall, the goal is to identify a lead source of the retinal venous pulsations (IOP pulsations, or alternative sources, e.g. cerebrospinal fluid pulsations).

Subjects will be recruited from the environment of the master thesis medical students, colleagues and friends and the informed consent will be handed to them personally. Exclusion criteria will be addressed. One random eye per subject will be selected. On the study day, first the mydriasis drops - phenylephrine + tropicamide - will be applied, then ECG electrodes attached; 20 minutes after the mydriasis drops, the first set of measurements will be performed: RVA recording with ECG gating, and Pascal Dynamic Contour Tonometry (DCT) recording with ECG gating. Ten minutes after this measurements, 100% oxygen 5 liters/min through nasal cannula will be applied for 2 minutes and then the same measurements repeated. Approximate time needed for the whole run - around 60 minutes per subject, including (dis)mounting the ECG electrodes and the mydriasis time.

Inclusion Criteria:

-

Exclusion Criteria:

Known ophthalmological disease, in particular vascular disease.