Final answer:
The critical time period for causing amblyopia in cats is within the first two or three months after their birth.
Step-by-step explanation:
The critical time period to cause amblyopia in a cat is during the first two or three months after birth. This is when the kittens are most susceptible to changes in their neural connections due to deprivation of sensory input. Renowned studies have shown that if kittens were deprived of visual input from one eye during this critical window, the visual cortex would adapt and reorganize, leading to amblyopia or 'lazy eye,' where the deprived eye's vision fails to develop properly.