Tilt and decentration of the implanted posterior chamber intraocular lens.

Management of surgically induced astigmatism is an important problem for surgeons implanting intraocular lenses. Besides corneal astigmatism, the fixation status of the intraocular lens (IOL) may contribute to total astigmatism. This study was undertaken to evaluate the effect of tilt and decentration of the implanted posterior chamber IOL on the total astigmatism. The tilting angle of the IOL was measured by a method using the 3rd and 4th Purkinje images, and the grade of the decentration was obtained photogrammetrically. The average tilt angle was 7.53 +/- 3.03 degrees (SD). The average decentration was 0.68 +/- 0.33 mm (SD) from the corneal center. Based on these data, the astigmatic error induced by the tilt or decentration of the implanted IOL was calculated as within 0.4 diopter. These data suggest that the fixation status of the IOL implanted in the bag does not cause a serious astigmatic error.