If the human eye was a camera, how many megapixels would it have?

The eye is not a single frame snapshot camera. It is more like a video stream. The eye moves rapidly in small angular amounts and continually updates the image in one's brain to "paint" the detail. We also have two eyes, and our brains combine the signals to increase the resolution further. We also typically move our eyes around the scene to gather more information. Because of these factors, the eye plus brain assembles a higher resolution image than possible with the number of photoreceptors in the retina. So the megapixel equivalent numbers below refer to the spatial detail in an image that would be required to show what the human eye could see when you view a scene.

Based on the above data for the resolution of the human eye, let's try a "small" example first. Consider a view in front of you that is 90 degrees by 90 degrees, like looking through an open window at a scene. The number of pixels would be 

90 degrees * 60 arc-minutes/degree * 1/0.3 * 90 * 60 * 1/0.3 = 324,000,000 pixels (324 megapixels).

At any one moment, you actually do not perceive that many pixels, but your eye moves around the scene to see all the detail you want. But the human eye really sees a larger field of view, close to 180 degrees. Let's be conservative and use 120 degrees for the field of view. Then we would see

120 * 120 * 60 * 60 / (0.3 * 0.3) = 576 megapixels.

The full angle of human vision would require even more megapixels. This kind of image detail requires A large format camera to record.

Also,

This is a complex question because our eyes have other wonderful features. the ability to instantly shift means that any shortcomings on resolution can be overcome by instant re targeting.

Our eyes have a much greater dynamic range than a camera sensor. meaning that we can see lighter lights and darker darks than any camera can. We switch between dark and light faster than a camera and we see dark without having to pause for a long exposure.

Add to this continuous auto focus and continuous auto aperture and you have a pair of mean cameras built tight into your head.

Furthermore there are two of them digitally linked in real time able to use the information combined or separately to produce an accurate image with remarkable 3 dimensional depth. Automatic fail over is included free of charge.

Add to that the fact that the batteries never go flat and they even come in a variety of colours!

Source:
Clark Vision