JohnJamesGood morning, JohnJames.
A large eye is one of those archetypical symbols that can be very powerful. You can regard it as the Eye of God, if you like. Essentially, there is the strong feeling of being under careful scrutiny, as under a microscope, with all that this implies. With that kind of attention, from a being so much larger (and therefore very powerful), one cannot help but feel inadequate and not a little threatened. This dream can have guilt as a source.
The reflection of a young woman can give us a clue as to the source of that feeling. Reflection is often symbolic of memory - something from the past, especially as she is looking "back" at you.
However, the timing of this dream casts a different meaning upon it. The images seen in the hypnagogic state are very primal - sometimes they spawn from infancy or before, sometimes they come from the movie we saw that evening. If this is a recurring dream, then I'd suggest the former is probably true - these are images that you retain from a very young age.
I'd suggest that some relaxing techniques would be a good idea - since this experience startles you so, you may be trying to go to sleep without adequate preparation.