Can the Xbox Kinect laser cause vision problems?
Solution 1:
The Kinect is classified as a class 1 laser device (Review from Anandtech), which means the maximum emitted power of the laser is <25 μW. This amount of power, according to current knowledge, is safe. It should not be able to cause lasting damage, it doesn't necessarily mean it is not capable of causing afterimages or similar effects.
According to the OpenKinect page the IR laser diode itself is capable of emitting 60 mW at 830 nm, which is far above safe limits. The signal is spread out, which reduces the intensity to safe levels. There seem to be some safety features built-in to ensure that. If those safety features would fail it would be theoretically possible for the Kinect to emit a harmful amount of IR. I cannot say how likely that is, though.
There is also an image of the Kinect IR pattern in the review, but it does not look like the pattern you described. You can see that pattern yourself using e.g. a smartphone camera or any other camera without an IR filter.
We humans also are not capable of seeing electromagnetic emissions in the IR range. But emissions in the near IR range (800-1400 nm) are still focused onto the retina and can damage it. Additionally, an IR laser will not activate the blink reflex, which normally would prevent further damage to the eyes. There are also no pain receptors in on the retina that could warn you, at the point were you notice the laser it will be too late and permanent damage has been inflicted.
I would personally doubt that the Kinect is responsible, but I'm not really qualified to estimate the probability of the safety measures of the Kinect failing and to judge the medical consequences of unsafe amounts of IR emissions.
I am not a doctor, this is not medical advice and I strongly recommend you to have your eyes checked by a medical professional.
Solution 2:
I have no particular expertise on the situation, but I would recommend going full scientist and trying to control for the potential causing factors. Three ideas that immediately come to mind would be to watch someone else play, to wear sunglasses while playing, and to play in varying ambient light levels. This would control for physical activity, many bands of EM radiation, and ambient contrast, each of which could not unreasonably result in discomfort or visual effects.
I suspect that varying one of these experimental conditions will make your symptoms go away, and you can subsequently verify and more specifically identify the responsible agent. I included physical activity among the major candidates since your description of the phenomenon you're experiencing has little literal similarity with radiation patterns emitted from the Kinect (and you say you've already controlled for different games), so the issue is unlikely strictly visual.
If on the other hand, nothing causes your experience to change, then I would just suggest looking for increasingly unusual factors (e.g., turning away from the TV so you can only hear what's going on while a friend plays).