Trāṭaka

Trāṭaka (Sanskrit: त्राटक "look, gaze") is a yogic purification (a shatkarma) and a tantric method of meditation that involves staring at a single point such as a small object, black dot or candle flame.

Description
The practitioner may fix attention on a symbol or yantra, such as the Om symbol, a black dot, the image of some deity or guru, a flame, a mirror or any point, and stare at it. A candle should be three to four feet (1 metre plus) away, the flame level with the eyes. The practitioner relaxes but keeps the spine erect and remains wakeful and vigilant.