Kittens have their eyes sealed; this is the natural way of nature protecting the eyes from damage and infection. Between 2 to 16 days of age their eyes start opening. There is no fixed time of opening eyes. Every cat can open their eyes at different times. When they open their eyes they can't see clearly as the vision is still developing. Till then, they depend on other sense of touch, smell and their mother.
By the time the kitten is 3 weeks old, their eyes are completely open. But, vision continues to develop over a period of months. If the eyes are clear and not red/pink then, their vision is absolutely fine.
When the kitten is about 2 weeks old, the open their eyes. Their eyes are of shade blue at this stage. Over the next few months, the color of eyes gradually changes to the color that the eyes will stay for all their life. Most of the adult cat’s eye colors are in the color continuum from green to yellow and yellow to orange and to copper. Cat breeds like Tonkinese and Siamese have blue eyes.
The transition period of the kitten’s eye color changing from blue to permanent eye color, one might even see different colors. These are called color flecks. These take place because of pigment cells. Cat’s eye, just like humans is determined by genetics.
If the cat's eyes are shiny and seem healthy then, they can see very well. By 8 weeks of age, their eyesight is matured completely. There are a few cat breeds that take about three months to transition to permanent eye color and take a year for their eyes to darken and mature to permanent eye color and hue.
A healthy kitten's eyes should be bright and clear. Signs of an eye infection are scratched eye from play or injury, cloudiness, eye swelling, continuous blinking, discharge, squinting and watery eyes. Conjunctivitis is a highly contagious eye infection seen in cats.
So, if you notice any changes in the eyes of your kitten, it is best to get them checked by the vet. By doing this, your kitten can live a healthy, long life!