Study of Two-step Anesthesia in Posterior Vitrectomy

Study Overview
=================
Brief Summary
-----------------
A prospective, randomised, single-masked comparison of local anaesthetic approaches including topical anesthesia combined sub-conjunctival anesthesia(two-step anesthesia) for minimally invasive vitrectomy（TAMIV）vs peribulbar block vs retrobulbar block

Detailed Description
-----------------
Purpose: topical anesthesia combined sub-conjunctival anesthesia(two-step anesthesia) for minimally invasive vitrectomy Methods: This prospective, randomized, single-blinded clinical trail is conducted at Shanghai Aier Eye Hospital. Selected group of 60 patients with retinal-vitreous diseases will be randomized divided into 3 groups and underwent 25-gauge vitrectomy. Group1 uses two-step anesthesia , whereas Group 2 uses retrobulbar anesthesia, group 3 uses peribulbar anesthesia. A 5-point Visual Analogue Pain Scale is used to assess patients' pain score and surgeon's ease while operating. Any complications therefore will be made note of.

Official Title
-----------------
A Prospective, Randomised, Single-masked Comparison of Retrobulbar Anesthesia, Peribulbar Anesthesia and Topical Combined Subconjunctival(Two-step) Anesthesia in Posterior Vitrectomy

Conditions
-----------------
Anesthesia, Local

Intervention / Treatment
-----------------
* Procedure: retrobulbar anesthesia
* Procedure: peribulbar anesthesia
* Procedure: two step anesthesia


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Proliferative diabetic retinopathy (PDR); Vitreous haemorrhage (VH); Retinal detachment (RD); Retinal vein occlusion(RVO); Other diseases (idiopathic macular hole, macular pucker and high myopic maculopathy); Silicone oil-filled eye. Exclusion Criteria: Communication problems; Allergy to amide-type local anaesthetic agents; History of vitreoretinal surgery or orbital surgery; Orbital deformity; With episcleral adjunct surgery; Trauma; Keratitis; Conjunctivitis and active uveitis.

Ages Eligible for Study
-----------------
Minimum Age: 30 Years
Maximum Age: 85 Years

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

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

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

Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: retrobulbar anesthesia group<br>2% lidocaine 4ml injected into retrobulbar space | Procedure: retrobulbar anesthesia<br>* 2% lidocaine 4ml injected into retrobulbar space<br>|
| Active Comparator: peribulbar anesthesia group<br>2% lidocaine 4 to 8ml injected into peribulbar space | Procedure: peribulbar anesthesia<br>* 2% lidocaine 4 to 8ml injected into peribulbar space<br>|
| Experimental: two step anesthesia group<br>conjunctival cul-de-sac anesthetized with 0.5% proparacaine hydrochloride drops three times + 2% lidocaine 0.6 to 0.8ml subconjunctival injection | Procedure: two step anesthesia<br>* conjunctival cul-de-sac anesthetized with 0.5% proparacaine hydrochloride drops three times + 2% lidocaine 0.6 to 0.8ml subconjunctival injection<br>|

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

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| pain scores | 5-point Visual Analogue Pain Scale(VAPS): Grade 1: No pain or discomfort; Grade 2: mild pain or discomfort; Grade 3: moderate pain or discomfort; Grade 4: severe pain or discomfort; | During surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| surgeon's ease | Grade 1: No discomfort; Grade 2: mild discomfort; Grade 3: moderate discomfort; Grade 4: severe discomfort; | During surgery |