You haven't trained hard until you've seen the White Buffalo.
I've done a search and I can't find anyone with exactly the same issue as I'm having.
On every working squat set I do, usually by the third rep on the way up I'm seeing purple lines which I think might be the outlines of the capilliaries within my eyes like you see on some advanced eye tests. Sometimes I can see them pulsate along with my heartbeat.
I see many accounts of something similar happening after the set which I get on deadlifts and feel a bit dizzy/faint, but none about it happening during the lift.
I am holding my breath for the lift and breathing at the top as I believe is recommended. I switched to breathing out on the way up but it still occurs.
Has anyone else had this? I'm just wondering if it's something I should be concerned about.
You haven't trained hard until you've seen the White Buffalo.
I can't answer they 'why' question, but it's not unusual for me to see white stars after sneezing, or during heavy squats. No problems while deadlifting though, which seems odd, since I deadlift a bit more than I squat.
I see stars almost every time I deadlift. Even with 225.
I've never seen "purple lines" but I have at times noticed my vision start to get a little blurry around the last rep and immediately following. I also manage to blow out like every capillary in my face, I typically look like hell afterwards.
Occasionally I'll get dizzy/close to blackout during deadlifts. The low 300 range seems to bring it on the worst for some reason even though it's not my heaviest.
That's weird.
I sometimes get a little dizzy after a hard set, once I've racked it, but not during the set. Maybe you're holding the valsalva wrong?
It is common to get Blue field entoptic phenomenon after releasing the Valsavla.
Eye capillaries are slightly too small for white blood cells to fit through them comfortably, and when your blood pressure spikes during the Valsalva maneuver, they temporarily get stuck and the red blood cells get in a traffic jam behind them. Your brain automatically filters what you see to compensate for less light flowing through the red blood cells turning up the gain on the photo receptors behind them, and when you release, the blood starts moving again. It takes a moment for things to catch up to the new state of things, so the photo receptors that had their gain turned up end up over-compensating briefly, and you see flashes of light that aren't really there.
Additionally, it is very common and generally considered normal for this process to result in small hemorrhages in these tiny delicate blood vessels for people in communities like ours that strive to lift really heavy shit during the valsalva maneuver.