CEA/CH causes abnormal development of the choroid - an important layer of tissue under the retina of the eye. Since the choroid layer does not develop normally from the start, the primary abnormality can be diagnosed at a very young age by an opthamologist. The clinical effects vary greatly among affected dogs within one breed, between parent and offspring and even within a litter. Most often the disease presents as a mild form in affected dogs and the presence of the disease can only be detected upon ophthalmologic examination; the dog retains normal vision throughout life. However, dogs with mild disease can produce severely affected offspring. The severe forms can result in serious vision loss or blindness in some cases. Inheritance of CEA/CH is approximately autosomal recessive. In some cases, the phenotype can vary to include colobomas and staphylomas in the optic nerve head and adjacent tissues ? which may be the only visible abnormality. This has led to some adult dogs in this category being termed so-called ?go normals?. The term ?go normal? has been applied to cases where post-natal development obscures the choroidal hypoplasia which is the key diagnostic feature, so that adult dogs have ?normal? appearance despite being genotypically affected. The phenomenon is common enough that many ophthalmologists recommend clinical examination to be focused on puppies/young dogs. This suggests other factors may have an effect on CEA/CH expression, i.e. that the disorder is multifactorial.