A multi-part intraocular lens (IOL) with an interchangeable optic seated on a base and secured by a locking mechanism. The optic comprises an anterior surface with a diameter greater than a diameter of a ring of the base. The posterior side of the optic has a posterior surface, a transition region for contact with the base, and sidewalls and tabs radially outward of the transition region. The sidewalls and tabs overlap at least a portion of the ring to reduce or even prevent decentration and tilt of the optic. Each tab has a lateral extension for coupling to the base.