Determination of the toric axis by using internal astigmatism axis in non-dilated eyes

Purpose To determine the toric intraocular lens (IOL) axis by using internal astigmatism axis obtained from Optical Path Difference (OPD) Scan III (Nidek Co.) in non-dilate eyes. Methods The eyes of patients who underwent toric IOL implantation for astigmatic correction were investigated. Patients who have ocular surface disorder, keratoconus, posterior capsule opacification were excluded. The IOL axis measured in non-dilated eyes in mesopic conditions by OPD scan III device and the IOL axis measured by using classical slit lamp biomicroscopy method in dilated eyes were detected at postoperative 1st and 6th months. Results were compared with correlation and linear regression analysis. Results Totally, 26 eyes of 18 patients were included. The difference between biomicroscopic IOL axis and OPD internal astigmatism axis was 4.96 ± 4.41 degrees at the 1st month and 3.62 ± 3.5 degrees at the 6th month. There was a significant and high correlation between biomicroscopic IOL axis and OPD internal astigmatism axis at both 1st month ( r = 0.992 p < 0.001) and 6th month ( r = 0.995 p < 0.001). According to regression analysis, the results of two measurement methods were significantly compatible with each other at 1st month ( R Sq = 0.984 p < 0.001) and 6th month ( R Sq = 0.990 p < 0.001) and there was a close to ideal linear ( R Sq = 1) relationship between two methods. Conclusions In eyes with toric IOL implantation, the IOL axis and IOL rotation according to target IOL axis can be detected easily and effectively in a short time by OPD scan internal astigmatism axis without the need to dilate the pupil.