Group receiving vibration-assisted anaesthesia

All anaesthetic injections will consist of xylocaine 1% with 1:100,000 adrenaline and will be administered through a short 30 Gauge needle at a constant slow speed at multiple (6-7) sites along the upper lid by a single oculoplastic consultant.

The vibration device and placebo will be operated by a single oculoplastics fellow. The vibrating device / placebo will be placed on the middle of the forehead 1 cm above the mid-brow point 1 second before the anaesthetic injection is commenced. It will be lifted off the skin every time the injection needle exits the skin and it will be replaced on the same point 1 second before the needle reenters the skin at a new injection site.

Group receiving switched-off vibrating device

The placebo consists of a switched-off vibrating device applied to the test site and a second identical switched-on vibrating device held close (but not touching) the first, which will therefore make the same sound. Care will be taken to ensure that the devices are out of the participants' view. The test and placebo will be randomly assigned to either the first or second eyelid; the right eyelid will be injected first in all patients, as is our routine practice.