If evolution occurs through gradations, the critics say, how could it have created the separate parts of the eye -- the lens, the retina, the pupil, and so forth -- since none of these structures ...

Simulations comparing the eye's actual lens shape with other models of hypothetical crystalline lens shape (with the same optical power) show that, although they all achieve paraxial focus ...

Cataracts are an incredibly common condition that creates a cloudy area on the lens of the eye. As a result, your vision may be blurry or unclear, and colors may seem less bright or hazy and faded.