Newborn kittens can open their eyes after 8 days. It takes about 14 to 15 days for kittens to fully open their eyes. When kittens are born, their eyes are just slits; they can fully open their eyes after 15 days.

When a kitten first opens its eyes, there is a thin, bluish-gray membrane on the surface of its eyeball. This membrane protects the kitten's eyes and gradually disappears as the kitten grows. Therefore, when a kitten first opens its eyes, it is recommended that owners do not keep the kitten in a place with strong light to prevent it from injuring its eyes while playing.