For most that is a silly question as it seems very obvious that it would be far too dangerous to run dog agility with a blind dog. Well, the authorities agree, you cannot compete with a fully blind dog. However, while you may not be able to compete with a blind dog, they can benefit from body awareness exercises as long as you keep their safety in mind at all times and take it slow.
And while you may not be able to compete with a completely blind dog, several venues accept dogs who are blind in one eye or have visual impairment. Some dogs are diagnosed with Collie Eye Anomaly which results in serious holes in their vision. Depending on the severity and the dog, they can do just fine once they learn to trust their handler and work around their disability. Some dogs, have what is called Early Take-off Syndrome (for more information, check out Linda Mecklenburg’s site.)
Once your dog is diagnosed with a visual impairment, discuss with your vet first and then your trainer, on how to proceed with training for your dog. Maybe verbal commands would be better, or handling from their seeing side. Your dog can learn to negotiate a course with slow, consistent training that allows your dog to build their confidence and find the best way to communicate with you on course.