This short paper presents the rationale against critical periods, in particular in the condition of amblyopia or lazy eye. For years, behavioral optometrists have been treating amblyopia successfully at all ages. Ophthalmology has adopted the stance that a critical period exists beyond which no treatment of the amblyopia can take place. Over the years the age that they have used has gotten older and older. This paper includes the scientific basis for the effectiveness of optometric intervention. The conclusion is that critical periods for amblyopia in humans is a myth.