intentness on a single point (ekagrata) of the thinking principle (citta) gives rise to equilibrium of placid states (previously accumulated impressions) and aroused states (present eagerness to gain more knowledge), which are modifications (of the mind).
focused or "one pointed" awareness or concentration, the ability to focus the mind on an object without distraction for extended periods of time.
Ekagra/one-pointed: The Ekagra mind is one-pointed, focused, concentrated (Yoga Sutra 1.32). When the mind has attained the ability to be one-pointed, the real practice of Yoga meditation begins.
Ekagra - one-pointed awareness
Ekagrata - one-pointed awareness or concentration; the ability to focus the mind voluntarily on an object without interruption for extended periods of time.
Ganesha - in mythology, the elephant-headed son of Shiva and Parvati; the god who removes obstacles ...
ekagra = a focussed state of mind
ekuna = minus one
Galava = The pupil or son of Viswamitra
garbha = womb, foetus
garuda = a fierce bird of prey, the vehicle (vahana) of Vishnu
ghatavastha = intermediate stage of yoga, when the mind and body learn to move together ...
The one-pointed concentration of mind is termed '~ta'. There are numerous distractions which obstruct ~ta. Association and identification through the eyes and sight are major contributing factors to this leakage.
CHANCHALATA (Multiple object, Multiple thoughts),
~TA ( Single Object, Multiple thoughts)
DHARANA ( Single object, Single thought ),
DHYANA ( Single object , single thought effortlessly) ,
SAMADHI( Only the object with single thought shines) ...
repulsion; something which brings pain or enmity
the state of one - pointed attention ...
He had the highly developed ~ta of a Yogi. He could draw, as it were, any single thought from the brain pigeon-hole, dwell on it as long as he liked and could shove it back when finished. He would sleep very soundly at night amidst busy war, would never worry a bit at night.
Thus, the use of a drishti allows the mind to focus and move into a deep state of concentration. And the constant application of drishti develops ~ha, single-pointed focus, an essential yogic technique used to still the mind.
See also: What is the meaning of Yoga, Mind, Meditation, Hatha, Prana?