Could someone give me (or point me in the right direction of) more information on colobomas that are not linked to CEA in border collies. My only understanding at present is that puppies should be screened before 12 weeks of age but I can't seem to find anymore information. :(

Colobomas are caused by increased tortuosity of retinal blood vessels. Colobomas are present in some individuals, visible in the optic disk or inferior to it. These colobomas can be extensive, four to five times the diameter of the normal optic disk. Some retinal detachments that can occur, cause visual difficulties, and defects in the central vision have been associated with the presence of large colobomas.

Link :-)

> Colobomas are caused by increased tortuosity of retinal blood vessels. Colobomas are present in some individuals, visible in the optic disk or inferior to it. These colobomas can be extensive, four to five times the diameter of the normal optic disk. Some retinal detachments that can occur, cause visual difficulties, and defects in the central vision have been associated with the presence of large colobomas.

Thanks, can you explain why they can only be detected prior to 12 weeks?

What age do they start to pose problems to an affected dog or does it vary?

I must admit this is confusing me a bit. :s

My understanding of the puppy eyescreening by 12 weeks was that choroidal hypoplasia could become undetectable more commonly than coloboma's, although I believe it can depend on the size of the defect, and have infact heard of a dog who's coloboma only became apparent as he grew and was not picked up at puppy testing.