That's no different from the problems you need to engineer around in a CCD or CMOS - stuff like dark current, shot noise, read noise, RGB filters effectively dividing resolution by 3, an upper limit on integration time which is almost the same as "sensor zeroes out if exposed to the same color for ten seconds".

OTOH, the eye's selective resolution and instant slew+focus of the high resolution spot together give it an effective resolution north of 600 megapixels. The auto-exposure is also pretty bad ass.