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.
If you ignore the RFE, USCIS will make a decision based on the submitted evidence, which generally will be unfavorable. It varies from a few days to more than 60 days. After 60 days if you have heard from the USCIS you may file call the National Customer Service Center to file a Service Request.