not got all info yet as waiting on friend getting back to me regarding what her vet said. but the gist of it is
her border collie pup bred from parents both dna cea normal
her vet said the pup still would be better with cea eye test done as some thing???? (friend cant remember what) can be missed in a DNA test especially in merles
Now i was under the impression these blood tests mean either normal carrier of effected
anyone idea what the vet is talking about and why the pup is still to get eye testing done.

All breeds affected by CEA(CH)should still be eye screened as puppies this is because colobamas can be present even in a dog that is genetically CEA clear. The quote below explains it better than I can

What causes the more severe forms of CEA?
No one really knows. It seems likely that other genes the dog carries can produce colobomas in dogs with the choroidal hypoplasia gene, even though they seem not to cause any problems where the choroidal hypoplasia gene isn't present. The gene or genes responsible have yet to be identified, and no tests are available. These genes could be carried silently in dogs which are clear or carriers for choroidal hypoplasia.

Colobamas

More severely affected dogs may have pits (colobomas) affecting the retina and adjacent tissues.

so even although the pup has 2 normal tested parents, CEA can still be produced??????

Colobomas can still be produced. Its still in research stages but different genes cause colobomas and although they have always been linked to CEA may not be the only reason for them occurring.

The DNA test is for Collie Eye Anomaly /Choroidal Hypoplasia & as Sandra has written Colobamos are not always linked to Collie Eye Anomaly /Choroidal Hypoplasia