Anaesthesia for Ophthalmic Surgery: How Retro is the Peribulbar Block?

Study Overview
=================
Brief Summary
-----------------
Ophthalmic surgery on the posterior section of the eye can either be performed under general anaesthesia or under local aneasthesia. The local anaesthesia is performed by injecting local anaesthetics behind the eye. There are two techniques: Either the needle is placed into the muscle cone formed by the four recti muscles - this is called intraconal or retrobulbar block, or the needle is placed outside of the muscle cone - this would be called extraconal or peribulbar. In our hospital the investigators usually perform the peribulbar block since it is easier to perform and has a smaller risk to injure the eye. The investigators however realize that the parabulbar block is sometimes very efficient and sometimes not, thus requiring a second or third injection. Now investigators are able to visualize where the local anaesthetics spreads with the help of ultrasound imaging. The aim of the study is to observe and to describe the incidence of intraconal spread of local anaesthetics when a peribulbar block is performed.

Official Title
-----------------
Anaesthesia for Ophthalmic Surgery: How Retro is the Peribulbar Block?

Conditions
-----------------
Ophthalmic Surgery, Parabulbar Block

Intervention / Treatment
-----------------
* Procedure: Ultrasound detection of local anesthetics spread


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: -informed consent Exclusion Criteria: coagulation disorder INR over 1.5 and/or a platelet count less than 75 X 109/L, pathological myopia, inability of the patient to lie down for the operation for more than 2 hours lack of informed consent.

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Ophthalmic surgery patients<br>Patients (men and women) of at least 18 years of age undergoing an ophthalmic procedure on the posterior section of the eye under local anaesthesia, i.e. with a peribulbar block. Inclusion and exclusion criteria for the study are the same as for the peribulbar anaesthesia. | Procedure: Ultrasound detection of local anesthetics spread<br>* During the parabulbar injection the ultrasound operator experienced in ultrasound guided retrobulbar block will assess whether there is spread of local anaesthetic in the central cone just behind the sclera (yes or no). The anaesthesist performing the block will be blinded to the ultrasound visualized spread of local anaesthetic.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of detectable retrobulbar spread of local anaesthetics during peribulbar injection. | The outcome measure is the description of the spread of local anesthetics during the injection of the drug via the parabulbar needle. | At start (During peribulbar injection) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Assessment of block quality | Assessment of the block quality by ophthalmic surgeon just before surgery starts and at least 20 minutes after the block: complete akinesia and anaesthesia or partial akinesia/anaesthesia. | 20 Minutes after block | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Ultrasound, retrobulbar, parabulbar, ophthalmic surgery.