Rotational slit-beam marking: an advanced manual corneal astigmatic marking method for toric intraocular lens...

To evaluate the accuracy of an advanced manual corneal astigmatic marking method for toric intraocular lens (IOL) implantation.

From 52 patients, 52 eyes with cataracts and corneal astigmatism were included. The target axis of the toric IOL was marked with the new manual marking method preoperatively and with the Zeiss CALLISTO Eye image-guided system intraoperatively. For the manual method, a slit-lamp with a minimum rotation angle of 5 degrees was used and rotated to the meridian of the toric IOL and incision axes. The relative rotational and vertical deviation of the IOL and incision axes were measured using the digital marker as a reference.

There was no significant difference between the manually marked IOL axis (100.9° ± 65.62°) and the digital mark (100.8° ± 65.76°; P = 0.771). The absolute values of the relative rotational and vertical deviations of the manually marked IOL axis were small, at 2.03° ± 1.44° and 0.46 ± 0.43 mm, respectively. There was no significant difference between the manually marked corneal incision and the digital meridian (P = 0.179). Then, patients were classified into three groups based on the type of astigmatism they had. There was no significant difference in mean absolute deviation among the groups (P = 0.112). The manual incision mark had a relative rotational deviation of 1.65° ± 1.44°. The vertical misalignment of the manually marked incision axis was 0.27 ± 0.30 mm.

Rotational slit-beam marking could be an effective and convenient marking method for toric IOL implantation. This method could be a potential alternative in underdeveloped areas where digital image-guided systems are not available.