The BCIG has set up a Candidacy Working Group and is working closely with other organisations to review candidacy requirements in the UK and develop an action plan for reforming candidacy criteria for cochlear implantation. The Cochlear Implants International Special Issue: Issues in Cochlear Implant Candidacy is available open access here.

Here is the Candidacy Working Group consensus statement:

Here is the website for the Action Group on Adult Cochlear Implants

Have a look at some background from the World Health Organisation:

Have a look at the worldwide candidacy criteria summary:
Worldwide Candidacy Summary Web Version 1.0