I don’t believe it’s scientifically validated, and I don’t have a direct link off hand, but check out Trataka, which is staring at a fixed object for a set amount of time (e.g. a candle or an image with a dot).
HealthyGamerGG YouTube channel has videos on it.
Apparently the yogis have been doing it for 1000s of years.
Netra Trataka to be specific(Netra- Eyes). My dad has been practicing yoga for the last 30 odd years(he is 75 this year) survived a near fatal Heart attack(occlusion) but doing well now with the help of couple of stents and Yoga!. This stuff works. For the real.
HealthyGamerGG YouTube channel has videos on it.
Apparently the yogis have been doing it for 1000s of years.