I've seen this question brought about before, on an older thread...here's the link:
http://www.alienvspredator2.com/comments/11447.html
As with the point I made back then, the original Alien did have indentations in its somewhat visible skull, but these were empty. It was originally just part of the costume design. As the franchise continued onward, these were completely removed, but some individuals still believe that they still exist.
In my personal opinion, those indentations may hold some other sensory organ, but certainly not eyes. If you read my Xenomorph Biology thread (which is lurking around page 4), I provide information on how xenomorphs actually can see through a wide variety of spectrums without possessing our version of eyes.
And thus I clothe my naked villainy
With old odd ends stolen forth from holy writ
And seem a saint when most I play the devil.