What is CEA- Collie Eye Abnormality.?
Collies share Collie Eye Anomaly (CEA) with several other breeds – it’s not just a problem for collies. CEA is more technically known as Choroidal Hypoplasia (CH). It is a recessively inherited eye disorder that causes abnormal development of the choroid - an important layer of tissue under the retina of the eye. This disease is seen most frequently in U.S. collies, but also worldwide in Rough and Smooth Collies, Border Collies, Australian Shepherds, Lancashire Heelers, and Shetland Sheepdogs. Since the choroid layer does not develop normally from the start, the primary abnormality can be diagnosed at a very young age. Regrettably, there is no treatment or cure for CEA.
The symptoms and signs – the clinical phenotype – can vary greatly among affected dogs within one breed, between parent and offspring and even within a litter. This creates a difficult situation for the breeder. Learning about the genetic cause and the course of the disease will help you understand how to manage it better and eventually avoid it altogether with genetic testing.
The primary problem is choroidal hypoplasia (CH). There is under-development (hypoplasia) of the eye tissue layer called the choroid. The choroid appears pale and thin, almost transparent, and the blood vessels of the choroid can easily be recognized in those “thin” areas. The ophthalmologist, looking at the back of the eye (the fundus) with an ophthalmoscope, typically will see an area of choroidal thinning that appears like a “window” to the underlying vessels and sclera.
The OptiGen genetic test for CEA/CH provides a powerful management tool for the breeder. This genetic test can distinguish all three genetic states – normal, carrier and affected. With this information, the breeder can plan matings that avoid producing any affected dogs by always selecting one parent that is normal. The other parent can be normal, carrier or even affected, and no affected dogs will result. (See table at the end.) This breeding recommendation is a big step forward, especially for breeds and countries where frequency of CEA/CH is much lower.
All my dogs are tested clear or are clear via parentage for CEA.