To fix one's eyes on a single point on a slant wall, or tip of the nose and the like, by keeping them wide-open and unblinking; through this practice, Samādhi (1) (concentration of mind) free from any distraction of thought can be attained.
adu porisiṃ tinyaṃ bhittiṃ, cakkhumāsajja aṃtaso jhāi.
antarlakṣātmakena animeṣapreksādhyānena nirviklpasamadhiḥ siddhyati.
(Ā 9.1.5 Bhā)