Trataka is the process of cleansing the eyes and improving the vision.
In Patanjali's ashtanga yoga, the eight fold steps are -
Yama
Niyama
Asana
Pranayama
Pratyahara
Dharana
Dhyana
Samadhi
Trataka is in the category of Dharana, leads to higher concentration and calming down of the mind.
Types of Trataka
Regular Trataka - with focusing of eyes on the hand and movement of hand
Jyothi Trataka - focusing on a source of light
Location - Calm place, with less lighting
Light source - A traditional lamp lit in Prayer room is a good source. Better to use Ghee instead of oil to light the lamp. Light the diya. ensure there is no air or wind to disturb this. keep the light at the level of eyes around 3 - 4 feet away from the eyes.
Picture: Light source used for Jyothi trataka
Increased concentration
improvement in eye sight and correction of refraction errors
Chakshusopanishad - Upanishad for eyes
aradhya Deva : Lord Surya (Sun God)