Vision Issues!!?

Has either of them done a topography. This is a map of the surface of the cornea which could pick up any distortion. It may be a little difficult to achieve with your nystagmus, but it can be done. Have they tried a pinhole test to see if the vision could potentially be made better. (You look through a tiny hole to see the chart) Other than that, you may have a subtle retina problem. In any case, an anterior segment specialist and/or retina specialist visit may be in order. You should at least have an explanation for the decrease in vision, even if it can't be helped......good luck.