What is "Secharchar"?
Rashi: It is surrounded 1 by sighing. The last two letters of the root are doubled, like "Yerakrak", "Adamdam" (Vayikra 13:49), Segalgal (Nedarim 66b), "Chamarmaru" (Eichah 1:20).
Radak: It cannot stand. One who is calm, his heart is serene. One who has many afflictions, his thoughts go around to and fro.
Malbim: My heart is surrounded by all bodily powers, which gather around it at the time of death. My strength and all bodily powers left me, and gathered to the heart to die there.
Radak: The Targum of "Saviv" (Bereishis 23:17) is Sechor Sechor.
Why did his eyes get weak?
Radak: One who is ill or afflicted, his limbs and body weaken, and also his vision.
Malbim: Vision is a person's connection to the sensory world around him; also it is not with me.
Why does it say "Gam Hem"? It refers to light, which is singular!
Radak: We find so often, e.g. "Keshes Giborim Chatim" (Shmuel I, 2:4), "Kol Negidim Nechba'u" (Iyov 29:10). Also my eyes, their sight was stricken; they are not with me.
