Hey there! I've got an odd problem, and I can't seem to find a fix for it anywhere... I've never seen this problem come up in the past, so I'll try to explain it well, as well as provide a video so you can get a better idea of what's happening...
So! As of recently (I haven't always had this problem) while using GLSL shaders, it sort of... breaks... whenever I look at an entity. What I mean by "breaks" is something in the rendering process seems to stop working properly, getting a different odd result depending on the shader pack I use. In the video, I use kuda, Continuum, and Chocapic, as well as the internal shaders, so you can see 1) it's not just a particular pack, and 2) maybe you can find where the problem is based off the consistencies between the different packs.
Here's a list of all the mods I have installed as well:
RPG HUD 184.108.40.206
Dynamic Surroundings 220.127.116.11
Fullscreen Windowed 1.6.0
Better HUD 1.3.9
HWYLA (Here's What You're Looking At) 1.8.20 B35
Inventory Tweaks 1.63
Item Zoom 1.9
Just Enough Items 18.104.22.168
Mouse Tweaks 2.8
Optifine Ultra C6
TorosCrafts Damage Indicators
WAWLA (What Are We Looking At) 2.5.246
I've played with most of these mods and Optifine/shaders before without this problem, and I've tried playing without HWYLA, WAWLA, and Damage Indicators, so I don't think it's an issue with another mod.