People ask: “when do kittens open their eyes?”. The answer is that most kittens open their eyes sometime during their second week of life. There is considerable variation in the time when kittens first open their eyes. The range is from 2 to 16 days after birth. This page reported a perceived problem.
Various Influencing Factors
Laboratory experiments (!) have demonstrated that several factors influence the timing. These include paternity, the kitten’s sex, the age of the mother and exposure to light.
For example, kittens reared in the dark opened their eyes earlier. Kittens of younger mothers and female kittens also opened their eyes earlier.
Paternity is the most important factor. By this it is meant that inherited genes strongly influence the timing of eye-opening by kittens.
Vision begins to play a more important role in their lives when they are about three weeks of age.
Their eyesight improves gradually until the fluids in the eye clear at about five weeks. Visual acuity improves on an ongoing basis until the kitten is three or four months old.
See: Kitten Development
The source of this information is: 1988 – Behavioural development in the cat. In The domestic cat: The biology of its behaviour, edited by DC Turner and P Batterson and published by Cambridge University Press via the excellent book Wildcat of the World by Mel Sunquist and Fiona Sunquist at page 109.