What characteristic is vital for the healing process after radial keratoplasty?

The characteristic that is vital for the healing process after radial keratoplasty is the central host-graft interface. This area is crucial because it represents the junction between the corneal tissue of the host and the graft tissue that has been transplanted. The success of the procedure largely depends on how well these two tissues integrate and heal together. Proper healing at this interface can influence visual outcomes and the overall success of the graft, as it needs to maintain stability and transparency to restore optimal vision.

Other factors such as the use of antibiotics are important for preventing infection, while follow-up lens fitting can assist in vision correction post-surgery. However, these factors do not directly address the fundamental biological process of healing at the site of the graft, which is why the host-graft interface is considered vital in the healing process. Age may influence healing rates, but it is not as directly critical to the success of the graft integration as the interface itself.