trāṭaka

It is the fifth of the ṣaṭkarmas (six haṭhayogic practices meant to purify the body). It consists in gazing at any small object without winking until tears begin to flow. This practice is supposed to confer clairvoyant powers apart from curing all diseases of the eyes (Gheraṇḍa Saṁhitā 1.53, 54).

See ṢAṬKARMAS also.