Let's take a look at the four ways we can transform a tangent function and graph. A changes the amplitude, or how steep the graph is along the y axis. B changes the period, or how wide one pattern of the graph is. C changes the phase shift, or how the graph is shifted to the left or the right. D controls the vertical shift, or how the graph is shifted up or down.
Wear your corrective lenses to see where you are going or it won't be just eyes hurt. Floaters, the little bits of scar tissue in the jelly of the eye that lead or lag behind the motion of the eye thus drift or float are made worse in excessive eye rubbing or worse can lead to retinal tears or detachment. Avoid this practice. Treat the itching if that is what the problem is in the first place.
Usually holes and tears do not mean you will have serious vision problems right away. However, retinal holes and tears may cause fluid from the center of your eyeball to leak behind the retina. If enough fluid gets behind the retina, the retina can separate from the back of your eye. The detached part of the retina will not work properly.