The internet is a wonderful resource
http://www.clickhearing.com/pdf/flying_and_the_ear.pdf
Grommets and perforations
Do not worry if you have grommets – very small ventilation tubes that
are inserted in the eardrum to treat conditions such as glue ear – or
perforated eardrums as a result of infection or injury. In either case,
flying is actually less of a problem than if the eardrum is intact. This is
because any change in pressure can be equalised across the eardrum
and does not depend on the Eustachian tube functioning normally.