The influence of two intravenous (IV) sedative regimens on intra-ocular pressure (IOP) was investigated in conjunction with retrobulbar local analgesia. Forty patients of either sex, and similar age with body weight within 40-90 kg were allocated equally and randomly to two groups: Group A (alfentanil/promazine) and group M (meperidine/promazine). Measurement of IOP, systolic pressure, pulse rate, respiratory rate, PaCO2, PaO2 and O2 saturation were made before operation, after premedication, after IV sedation and post-operatively. In the Alfentanil group there was significantly stronger decrease of IOP (p < 0.001). In group A the IOP dropped from 18.1 +/- 3.2 mm Hg to 10.3 +/- 2.7 mm Hg, i.e. 43%, while in group M the reduction IOP was from 17.6 +/- 3.5 mm Hg to 12.6 +/- 1.9 mm Hg, i.e. 28.4%. Meperidine caused a significant increase in PaCO2 (4.2 +/- 0.3 mm Hg), however this increase was not sufficient to cause the IOP alterations. The oxygen saturation was lower in group M (decreased by 1.5 +/- 1% in group M versus decrease by 1.0 +/- 1.2% in group A). Cardiovascular parameters were more stable in group A. In conclusion the alfentanil regimen produced a better reduction of the IOP with excellent sedation, operative condition and least anaesthetic side effects.