Sasuke decided that he didn't like Sound Village. The Sound Village was cold and dark and covered in a semi-translucent sheen of riches and power. He was learning new Jutsu at an acceptable rate, not at the unholy rate that Naruto learned them, but acceptable. And there was the gap. A chunk out of his mind (sanity,heart) was not there. It was a portal (wormhole,blackhole) that dragged in everything else (there goes the world). It twisted the world, warping Sasuke's eyesight. Reality bent (broke), Sasuke didn't know that reality could bend (break). So reality twisted (distorted), blood boiled and frothed (that isn't blood, blood isn't blue) and pictures splayed themselves out in garnish displays of violet and viridian (and where the hell did that pink come from) and almost every color know and unknown to man before disappearing into darkness (oblivion).
And Sasuke trained because it was only when he was on the verge of passing out from chakra exhaustion that the gap (blackhole) shrunk to a pinpoint and he could finally see the world. Then Orochimaru would smile at his new Jutsu in that condescending way that only he could pull off and still look shit-yourself scary while doing it. An "Aww, look, I taught him that. Let's go watch and take pictures for the album while he massacres people with it." look. And the gap would be back (it never left) and growing and reality would be different (sense when did Kabuto have boobs) and it was so much harder to ignore it and not break down screaming but he had to because if he started he would never be able to stop. And the gap (blackhole) never got as small as it was before and he was pretty sure that only junkies could see colors like that.
Sasuke was pretty sure that there used to be something (someone) on the other side that blocked it up and kept reality from slipping through. But he figures that he must have left it (him) behind in Kohna (what was Kohna). He had the vague impression of claws and fangs and crimson (bloodstained,blooddrenched) eyes stairing at him, judging him, laughing at him.
Sasuke knew that there was irony in the fact that he couldn't see red or orange or yellow anymore, but he couldn't figure it out at the moment.