Introduction to the last three ṣaṭkarmas. Trāṭaka is the fixation of the gaze upon a point — usually a candle or small dot — without blinking until the eyes water.

This practice cleanses the eyes (netra-doṣa-vināśana) and, according to the tradition, develops the capacity to see the nāḍīs (subtle channels) and other internal phenomena.

The sustained effort of not blinking strengthens the eye muscles and purifies external vision as preparation for the “inner vision” of meditation.