Scar tissue on the ear drum is usually caused by repeated ear infections. The scar tissue can lead to difficulty hearing and eventually ruptured ear drums. Surgery is one means of avoiding progressive hearing loss or ear drum rupture. No patients have reported taking Scar tissue removal (eardrum).
USCIS normally responds to RFE's within 60 days, however they do not have processing times on how long it takes them to respond. It can be longer than that. I would call the USCIS number: 1 (800) 375-5283 and submit a service request, if you do not hear from them soon.
It depends in part on what your provided in response to the RFE and any further review needed to issue a decision. Applications for EADs usually take 60-90 days to process unless DACA related, which take longer. You can call the USCIS customer service number to try and obtain more info: 800-375-5283.