Wudhu With Waterproof Eyeliner

If by “bottom of the eyelid” you mean the skin outside of the eyelid (just under the eyelid), then this skin is regarded as part of the face, in which case it will be necessary to remove the waterproof eyeliner for the validity of Wudhu.  

If on the other hand by “bottom of the eyelid” you mean the skin that is between the base of the eyelid and the actual eyeball, then this part of the eyelid, also known as the waterline, is part of the inner-eye and not part of the face. In Wudhu is not necessary for water to reach inside of the eyes. Hence if the waterproof eyeliner or Surma is applied to this inner portion of the eyelid (i.e., the waterline), it will not hamper the validity of the Wudhu. However, one should ensure that the waterproof eyeliner or Surma is not applied to the lacrimal caruncle area of the eye (i.e., the inner corners of both eyes that are towards the nose), as those corners of the eyes that reach the nose are regarded as external parts of the eyes and part of the face. Hence the waterproof eyeliner or Surma that covers these corners will have to be removed for the validity of Wudhu.

In essence, when the eyes are lightly (not tightly) closed, then whatever portion of the eyes are not visible are part and portion of the internal eye and do not need to be washed in Wudhu.