your father`s condition is related to dysfunction of eustachian tube( a tube which connects throat with ear), Due to blockage of eustachian tube a negative pressure is created in middle ear which leads to retraction of tympanic membrane, if untreated can lead to bone erosive condition (cholesteatoma
). Ideal treatment is surgery- removing weak retracted ear drum and putting a graft for strengthening the drum, But in your father`s case since one ear is dead, hearing valuation (audiometry
) should be done before surgery.
with best wishes , speedy recovery & good health.