Photo: National Socialist Racial Science: Color Palettes for Eye-Color Classification (1937)
"Eyes—Kind, friendly eyes imparting good temperament, intelligence and alertness are a hallmark of the breed. They should be of medium size, set well apart, and neither protruding nor deep set. Eye color should be brown in black and yellow Labradors, and brown or hazel in chocolates. Black, or yellow eyes give a harsh expression and are undesirable. Small eyes, set close together or round prominent eyes are not typical of the breed. Eye rims are black in black and yellow Labradors; and brown in chocolates. Eye rims without pigmentation is a disqualification."
—Official AKC Labrador Retriever Breed Standard
"Eyes—Friendly and intelligent in expression, medium large with dark, close-fitting rims, set well apart and reasonably deep in sockets. Color preferably dark brown; medium brown acceptable. Slant eyes and narrow, triangular eyes detract from correct expression and are to be faulted."
—Official AKC Golden Retriever Breed Standard