Natyashastra
चला हसितगर्भा च विशत्तारानिमेषिणी । किञ्चिदाकुञ्चिता दृष्टिः हृष्टा हासे प्रकीर्तिता ॥ ५७॥
Hṛṣtā: The Glance which is moving, slightly bent and in which eyeballs are not wholly visible (lit. entering), and there is winking, is called Hṛṣtā (joyful); it is used in laughter.
english translation
calA hasitagarbhA ca vizattArAnimeSiNI । kiJcidAkuJcitA dRSTiH hRSTA hAse prakIrtitA ॥ 57॥
hk transliteration by Sanscript