An implantable accommodating intraocular lens (IOL) has an optic lens sized to fit within a capsular lens bag of an eye; and a plurality of haptics angularly spaced around and radially extended from the optic lens, with each haptic: having a tongue that forms an arcuate sulcus gripping part that, in use within the capsular lens bag, inserts into and follows a circumferential groove of the sulcus to restrict circumferential sliding of the tongue around the sulcus; and being structured to move, under contraction and expansion of ciliary muscles of the eye, to adjust the optic lens to accommodate a focal power of the eye.