From the OFA website:

Is the OFA Eye Certification Registry (ECR) replacing CERF? Is CERF going away?

The American College of Veterinary Ophthalmologists (ACVO) designated the OFA’s Eye Certification Registry as their endorsed registry as of November 1, 2012, and in the first 18 months the OFA has successfully processed over 32,000 applications. ACVO diplomates (veterinary ophthalmologists) receive regular quantities of the OFA eye examination forms, and the ACVO is encouraging their use and registration of results with the OFA going forward.
UPDATE – On May 28, 2014 CERF announced that they will be closing effective June 15, 2014.
Continue reading Updated: FAQs regarding the conversion from CERF to OFA for eye exams →