Section 80 dd

I didn't get the certificate from the  CMO for the purpose of getting deduction under Section 80 DD last year and didn't claim any benefit.  Now, If i get the certificate,  can i claim the benefit irrespective of the fact whether i purchase the Hearing aid equipment or not? and whether the certificate has to be obtained every year as our accounts officer is having a different view on this.  Your valuable advice is solicited.