Traditional Blind Versus Ultrasound-guided Peribulbar Blockade

Study Overview
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Brief Summary
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Eye surgeries are traditionally performed under local anaesthesia with a peribulbar block. This is a blind technique where local anaesthetic is injected into the back of the eye to make the eye numb and motionless for surgery. This is a blind injection and can be associated with complications such as bleeding, rupture of eye globe, blindness, increasing the pressure of the eye etc. It also has a high failure rate resulting in need for additional injections, further exposing the patient to possible complications. The investigators propose to perform the peribulbar block with ultrasound to guide the block needle placement and injection. The investigators hypothesize that ultrasound guided peribulbar blocks would have higher success rate (less need for additional injections) and that the total amount of local anaesthetics used would be decreased.

Official Title
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Traditional Blind Versus Ultrasound-guided Peribulbar Blockade

Conditions
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Retinal and Infra-ocular Pathology

Intervention / Treatment
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* Procedure: Local Anaesthetic Injection
* Procedure: Ultrasound-Guidance


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients undergoing vitrectomy surgery Exclusion Criteria: Lack of informed consent Coagulopathic disorder, anticoagulated with INR (international normalized ratio) > 1.5 or platelet count less than 75 x 10^9/L Pathological myopia. Inability of patient to lie down for 2 hours for the operation -Local infection at site of needle entry

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Traditional blind peribulbar block<br> | Procedure: Local Anaesthetic Injection<br>* Local anaesthetic is injected into the eye.<br>|
| Experimental: Ultrasound-guided peribulbar block<br> | Procedure: Local Anaesthetic Injection<br>* Local anaesthetic is injected into the eye.<br>Procedure: Ultrasound-Guidance<br>* Device: Ultrasound Machine Peribulbar block local anaesthetic is injected into the eye with ultrasound guidance.<br>* Other names: Ultrasound Machine;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Failure of peribulbar block | Ocular Anaesthetic Scoring System (OASS) score of less than 10 will be considered inadequate for surgery and a block failure. | 10 minutes after block performed | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Quality of the block | Quality of the block based on the OASS score will be classified as poor (0-3), average (4-9) and good (10-14). | 5 and 10 min after block performed | 
| Incidence of Supplemental Peribulbar injections | To determine incidence of additional peribulbar injections after failure of original block as determined preoperatively by the anaesthetist or intraoperatively by the surgeon. | Operative day 0 | 
| Volume of Total Local Anaesthetic Used | The total volume of local anaesthetic used for peribulbar block preoperatively and intraoperatively. | Operative day 0 |