Clonidine als toevoeging voor de verlenging van pijnbestrijding bij oogoperaties.

Rationale:

Clonidine, as an adjuvant in neuraxial local anaesthesia, is generally recognized to prolong motor block and analgesia. It is conjectured to have a similar effect on peripheral nerves and, thus, might help to reduce post-operative pain and use of analgesics.



Objective:

To determine the beneficial effect of a single dose of 150 µg clonidine as an adjuvant to chirocaine in retrobulbar block.
Study design: Randomized, controlled, double-blind trial.
Study population: Patients with indication for retinal cryocoagulation and episcleral explant, or cryocoagulation of ciliary body.



Intervention:

Retrobulbar injection of 150 µg clonidine.



Main study parameters:

Maximal pain level, time of maximal post-operative pain, amount of escape medication used, time of use.



Nature and extent of the burden and risks associated with participation, benefit and group relatedness:

Participants receiving clonidine (group 2) may benefit from reduced pain. Burden of participants is negligible and study-related extra time is about 10 minutes. We anticipate the risk of side effects of retrobulbar administration of clonidine to be limited.

Clonidine as an adjuvant in retrobulbar block reduces post-operative pain and use of analgesics.

Primary parameters: 2 and 5 hours postop, bedtime at day of surgery, postop day 1.

Secondary parameters: 30, 60, 90 and 240 minutes after retrobulbar injection, and at postoperative day.

The investigational product of this study is clonidine, which will be used as an adjuvant in retrobulbar block. The efficacy of clonidine will be compared with a control group.

Group 1: Retrobulbar, Chirocaine 7.5 mg/ml: 3-5 ml;

Group 2: Retrobulbar, Chirocaine 7.5 mg/ml: 3-5 ml + clonidine 150 µg in 1 ml.