Trataka is a yoga technique of cleansing the organ of sight – eye. It is one of the six cleansing techniques of hatha yoga. Trataka is described in Hatha Yoga Pradipika (II. 31 – 32) as follows – one should gaze at a small object without winking till ears start rolling down. This is called trataka. It cures disorders of the eyes and helps to remove sluggishness and slothfulness.
More or less the same description is found in Gheranda Samhita (I. 54-55), where it is said that one gets divya-drishti (supernatural sight) by the practice of drishti trataka.
The practice of cleansing techniques (suddhikriyas or satkriyas) is recommended in hatha yoga for removing impurities from various parts of the body. Fixing the gaze, as is done in trataka, without the movement of the eyeballs involves a special exercise of the ciliary muscles of the eyes, which stimulates the tear glands to secrete and excrete their fluid. The movement of the mind is arrested by keeping the eyeballs fixed and motionless. When the eyes are filled with tears, the process of trataka is to be stopped. Its relevance for pranayama is not mentioned in ancient texts. The remark in Gheranda Samhita (I.55) that the practice of trataka leads to the highest state, like Shambhavi mudra, seems very important, and it would be advisable to study it in detail.
In trataka, various objects for fixing the gaze may be used, e,g., the flame of an oil lamp, an idol, or figure or picture, and so on.