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Intraindividual comparison of marking precision between the computer-assisted system Callisto and the manual pendular marker Tomark

Poster Details

First Author: B.von Jagow GERMANY

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Abstract Details


To compare the precision of a computer-assisted marker system for toric intraocular lenses (IOLs) (Callisto Eye System, Zeiss) with the manual marker Tomark (Geuder) in an intraindividual setting using intraoperative photographs.


Department of ophthalmology, Schlosspark-Klinik Berlin, Berlin, Germany


50 eyes of 41 patients who underwent phacoemulsification with toric IOL-implantation were included. Less than 3 months preoperatively, reference photos were taken with the IOL-Master. 15min before surgery, the target axis was marked with the Tomark pendular marker. Additionally the target axis was displayed as an overlay into the live image by the Callisto eye system during surgery. An intraoperative photograph was taken after the alignment of the toric IOL. Using ImageJ (NIH, Bethesada) the differences between the two marking methods were quantified.


The manual marking was partial in 17 eyes (23%), the computer-assisted marking were consistent. The widths of the Tomark markings were 10,8° (3,6° to 30,2°), the Callisto lines measure 0,7°. The angle difference between the Tomark and the Callisto markings were 3,5± 2,0 ° (0 bis 8°), in 68% clockwise. The shift between the Tomark and the Callisto markings were 0,21± 0,2 mm (0 bis 0,64mm). The shift between the markings of the IOLs and the Tomark and the Callisto markings were 0,39 ± 0,36 mm (0 bis 1,00 mm) and 0,23 ± 0,24mm (0 bis 0,62 mm), respectively.


The differences between the manual and the computer-assisted marking method are small. The computer-assisted method was superior regarding precision and centration of the marking.

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