Grommets are tiny tubes that can be inserted into the eardrums to treat conditions that affect the middle ear, such as recurrent middle ear infections and glue ear. Glue ear, also known as otitis media with effusion, is a persistent build-up of fluid in the middle ear that can cause hearing problems.
When the middle ear is filled with fluid, the ear structures become less mobile and less capable of carrying sound vibrations to the inner ear. The type of hearing loss this causes is referred to as conductive because the sound is prevented from being properly 'conducted' through the middle ear to the hearing nerves in the inner ear.
Grommets maintain normal middle ear pressure by allowing air into the space on the other side of the ear drum, from the outside. This reduces the risk of fluid building up in that space. If an ear infection does occur, the resultant pus flows out through the grommet, limiting the pain a child suffers.
Grommets are a temporary measure and will buy time while a child's Eustachian tubes grow to a sufficient size to work naturally. The Eustachian tubes connect the space behind the ear drum (middle ear) of each ear to the back of the nose
A grommet insertion involves a simple surgical procedure called myringotomy, where a small cut is made in the eardrum and any fluid is suctioned out. The grommets, also known as ventilation tubes, or tympanostomy tubes, are then inserted into the eardrums to drain fluid and ventilate the middle ear. The procedure usually takes about 15 minutes.
The procedure is done under a general anaesthetic. Grommets cause no discomfort while in place. They usually fall out on their own in 6 to 12 months, leaving the drum intact.
REFERENCES
https://www.kidshealth.org.nz/grommets-tympanostomy-or-ventilation-tubes
http://www.mydr.com.au/kids-teens-health/middle-ear-infection-and-grommets
http://www.mayoclinic.org/tests-procedures/ear-tubes/basics/definition/prc-20013911
http://www.rch.org.au/kidsinfo/fact_sheets/Glue_Ear