Ball python hisses at me in tank

[shelliebear]

Hi,
CleoMantra, around 1.8 to 2 years old, weighs 1,200 grams or so, has recently within the last 3 months begun to hiss at me when I go near him in his tank. Thus far he hasn't bitten or even s'ed up, he just hisses pretty loudly.
He's been off feed for about 6 months now, give or take one or two months. Anyway, admittedly, I've been pretty terrible about their humidity; in the winter it was drafty in the apartment, terribly so, and I was so focused on keeping them warm in their tanks with lamps and such that the humidity was dismal. I think I'd be stretching it to say humidity was 10%. That's my bad. I need to do better.
But anyway, Mantra's eyes are the worst out of all of my snakes, I sometimes worry he can't see out of his eyes. He used to be very head shy and now he pulls away from hands or things going near his face 80% of the time but 20% he doesn't react almost as if he can't see. He has some pretty seriously bad dents in his eyes, solid white cracks in there. he hasn't shed in a month or two.
I've been making it my mission, now it's warming up, to turn off the heat lamps and spray his tank CONSTANTLY, a minimum of 4 times a day, to help with the cracks. I was wondering if perhaps if I increase humidity, if his eyes would clear up, thus lightening his mood a little?
The hissing came about when the eye caps got worse.
Could his assumed bad vision be causing the mood issues and hissing? Or is it normal for some BP's to become tank aggressive? He's a baby when I get him out, totally fine, doesn't hiss at all. He just doesn't like being touched in his tank.
Any thoughts? What are your bp's like in their tanks? And advice on upping humidity is always a plus. I could use tips.
One more thing: Mantra hasn't pooped or peed in quite a while. Is this normal when they are off feed for as long as he has been?
Thanks all
Shellie