Wiktionary
vb. 1 to be no longer able to see 2 to forget about
Usage examples of "lose sight of".
I never wanted to lose sight of the fact that they were, at heart, the enemy.
I think she did not want to lose sight of the black man again so soon after we had found him.
Zachan made an effort to close up the ranks as quickly as possible so as not to lose sight of the prisoner for a single second.
Then he put the question that was obsessing him, the question he could not lose sight of, no matter how great was Maharet's spell.
He quickened his steps that he might not lose sight of him, but, having reached the avenue, found the trees so thickly interwoven, that La Motte was already hid from his view.
He would not be able to keep the man in sight, but to lose sight of him would mean taking a large risk.