corner of the eyes, eyesockets
眦 centers on the outer corner of the eye and the surrounding bony socket. It refers to the anatomical corner where the eyelids meet and the eye socket itself.
眦 combines 目 (eye) with 此, which likely contributes the sound. The character specifically denotes the corner of the eye.
The left side 目 is the eye, and the right side 此 looks like a stop sign with a person beside it. Imagine stopping at the corner of your eye where the eyelid meets the socket.
For セ, picture a sailor saying 'Aye aye, cap'n!' while pointing to the corner of his eye: 'say' -> セ, and the corner of the eye is where the sailor's gaze stops.
corner of the eye