Ojos Azules are remarkable for their deep blue eyes. Unlike the blue eyes seen linked to the genes in bicolor cats and cats with point coloration, both of which suppress pigmentation, this gene is not linked to any certain fur color or pattern, giving the opportunity to have cats with dark coats and blue eyes. The depth of color in the eyes is greater even than that seen in a Siamese (cat), and does not cause squinting, deafness or cross-eye. One indicator of the Ojos gene is a flattened tail-tip.  Following genetic investigation by Solveig Pflueger, breeding resumed in a small way with attempts to breed Ojos Azules without the lethal genetic defects. It was discovered that when the gene is homozygous it causes cranial deformities, white fur, a small curled tail, and stillbirth. However, when the gene is heterozygous, those lethal genetic mutations do not manifest. The result is that breeders must cross the blue-eyed cats with non-blue-eyed cats, assuring a litter of about 50/50 blue/non-blue-eyed kittens.