Yōga Sūtra 3.21

kāyarūpasaṁyamāttadgrāhyaśaktistambhē cakṣuḥprakāśāsamprayōgē'ntardhānam।

By samyama of physical body form, suspending eye's ability to grasp, obstructing the contact of light with eyes, disappearance (of object) is achieved.