In ophthalmic surgery the specific anaesthesiological challenges necessitate the administration of a combination of relatively high doses of hypnotics and analgetics. In order to preserve adequate organ perfusion, there is often a need to administer pharmacological agents for haemodynamic support. Depending on the experience of the anaesthetist a continuous infusion of phenylephrine or norepinephrine is used. It is currently not known which of these agents has the most favorable haemodynamical profile.

Haemodynamic parameters (continuous blood pressure, cardiac index, stroke volume and systemic resistance), peripheral tissue oxygenation and cerebral tissue oxygenation will be monitored noninvasively using the Nexfin® , Inspectra®, and Foresight® and O2C® monitoring devices.

Inclusion Criteria:

Patients requiring general anaesthesia for ophthalmic surgery.

• Age > 18 years and older
• Diabetes or cardiovascular disease or age >55 years

Exclusion Criteria:

• Patient refusal
• Patient < 18 years