Hi and thanks for the query.
Ventilation tubes especially those which remain in place for a long time can produce chronic middle ear inflammation
and a permanently perforated drum.
The middle ear is lined by smooth anfd flat mucus membrane.
Long standing inflammation of the middle ear can lead to hypertrophy of this mucus memebrane producing small bumps which you have seen through the perforated drum.
Your son definitely needs to be seen by an ENT specialist
for the persisting drum perforation and the inflamed middle ear mucosa.
Depending on the examination findings he may require ear drops, nasal deconestants and antibiotics.
Once his middle ear bumps go away he definitely needs a hearing test to determine the degree of hearing loss
caused by the perforated drum.
As for the perforation. since it has been present for more than a year it is unlikely to close on its own. Your son may require surgery.
Since he has a perforated drum you have to take water precautions which means no swimming, no diving or water sports. Please plug the ear with cotton smeared with vaseline while giving him a head bath.