Patients receiving toric IOLs should expect a small amount of residual astigmatism beyond predicted values even when the implants are perfectly positioned in terms of rotation, a ne w study suggest. A vector analysis study involving 18 eyes of 16 cataract patients implanted with There was a difference of 0.29 D between the target and achieved cylinder values. The postoperative IOL meridian placement completely corresponded to that planned. The astigmatism correction index (surgically induced astigmatism/targeted induced astigmatism) was 0.95, was near the ideal value of 1. The index of success (difference vector/DV/TIA) was 0.44, which was far from the ideal value of 0.