"It is dull enough to confuse the eye in following" = the eye has difficulty following it closely or really understanding it, because it is sort of shapeless or without a clear enough shine to it that would enable you to understand it. "pronounced enough to constantly irritate and provoke study" = it has enough character or strength or something noticeable to it that it does not let the eye leave it unnoticed, the eye keeps seeing it, and therefore it wants to study it. (This is irritating since when the eye looks at it closely it cannot really understand it, even though it tries to study it) "and when you follow the lame uncertain curves for a little distance they suddenly commit suicide—plunge off at outrageous angles, destroy themselves in unheard of contradictions." = And when the eye tries to understand this object by following its shape, it is left unsatisfied because the shapes are not very clear, not clear enough to follow, and at a certain point they even disappear by going sideways at strange angles, and this seems to make no sense, they don't seem to match one with the other (they contraddict each other). Wowwwwww what a confusing piece of writing!! It sounds like the description of a painting of modern art.

I think you need to examine your eyes sight first or buy another new glasses after visiting your doctor.