I watched mine one day and she would look all around then look where her foot was, it took her like 10 min to get her one foot moved to the next branch. It is fun to just watch her navigate the cage.
They have extremely far sighted vision. It is doubtful that they can make out a close branch as any thing other then a blur. It is normal. It is important to try to leave the cage like it is as best you can. Once they get settled into a cage for awhile they can navigate through it very gracefully.
A friend wrote an article that may be published someday. I didn't ask her where she got the data but knowing her, I'm sure that it was reliable...
Here's a quote:
"Comparatively, chameleons’ eyes produce the largest retinal image of any animal. Chameleons have evolved what has been described as a “mini-telephoto lens system” based on a myopic, divergent, lens, which creates a virtual image. Their eyes can focus as close as 3cm while the accommodation range is said to be up to 45 diopters and rapid, up to 60 diopters per second; similar to birds according to one expert."
If your chameleon continues to miss its target, there may be an tongue/eye-related health issue. Keep an eye on things .