To provide a disc-shaped recording medium whose tracks at borders of zones have header information to enable a pick up to transfer to a target track, and whose data fields are not influenced by crosstalk or double refraction caused by the header fields. The intraocular lens is foldable so as to be insertable through a small incision in the eye. A negative ion generator is used to boost the level of anions in the air before being discharged. An objective measure of system performance is defined prior to implementation of the present methods. The interference signal code power is calculated for each solution and the solution having the lowest weighted ISCP is selected as an optimal solution. In one embodiment, an apparatus includes a processor and memory including computer program code.