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.