It's a good question.. A case of ocular albinism was clinically reported in France. Some of them include diluted dresses: everything depends on the definition of albinism that is considered.
Mammalian albinism is generally at a genetic defect, total or partial, of melanin pigment production; By default of tyrosine, itself linked to the manufacturing defect or to the dysfunction of the enzyme tyrosinase; On the other hand, the melanocyte cells are present in the skin. In birds, reptiles and snakes there are pigments other than melanin, so the phenotype "white with red eyes" is not systematic. There are different diagnoses ... The differential diagnosis: we must theoretically distinguish albinism from white-dressed horses.
It is a rather complicated, controversial and evolutionary subject, following the genetic discoveries that will surely continue, and the discussion is open!
The full albinism doesn't exist because it's a pathology in the genes. Maybe in years it will change !