Hi Stan Yu,
You are spot on with your assumptions. Glasses do deteriorate accuracy and increases noise for a lot of users. Mind, not all users with glasses, but several. Same goes with direct sunlight or the precense of other equipment that emits light in the so called near infra red wavelength region. They can interfere.
So in short your experience that the accuracy improves when you take off your glasses follows the general trend. The stronger the glasses, the stronger the impact (typically). With that said a lot of people find that the EyeX Controller works remarkably well with glasses compared to other eye trackers.
And now on to some positive sidenotes. I appreciate your feedback. We are quite aware of this problem and are actively improving our algorithms and whenever there is a new firmwaer or EyeX engine up for download, you should check it out to see if you experience improvements. We are always happy for feedback.
Some brief comments on your observations 1 and 2.
1. Yes. Corners are typically most prone for accuracy offsets. However this is one area where we are right now focussing our development effort so look out for new releases.
2. Noise. With this sort of measuring system there will always be a risk of false detection, i.e noise, and in some cases the noise is big. You will however be happy to hear that this is another key focus area for our development team so stay tuned.
As the only real direct help I can give right now, you can check if your glasses are clean. Also if they are old and have a lot of scratches or marks it will deteriorate the quality of the eyetracking. But from your analysis I think that this is probably things you have already checked for.
Cheers,
Mattias