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.

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