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Intraoperative digital alignment of intracorneal ring segments: preliminary results

Poster Details

First Author: J.Alvarez de Toledo SPAIN

Co Author(s):    R. Barraquer Compte   P. Sauvageot Beneria   J. Lamarca Mateu   B. Salvador Culla           

Abstract Details


To study the feasibility of adapting the Verion�â�„�¢ (Alcon) Image Guiding System to the Visumax�Â�® (Zeiss) femtosecond (FS) laser to improve the intra-operative digital alignment of the ring segments during the FS-laser assisted ICRS surgical procedure and to analyze the preliminary results in patients with keratoconus or post-LASIK ectasia.


Centro de Oftalmolog�Ã�­a Barraquer of Barcelona. Institut Universitari Barraquer, Universitat Internacional de Catalunya (UIC)


We adapted the Verion�â�„�¢ Image Guiding System to the Visumax�Â�® operating microscope with an external light source to improve the eye-image capturing process. Eye image digital high-resolution captures were taken during the pre-operative exams and in the operative microscope just before starting the surgery. We marked with a surgical pen the 0-180�Â�º axis, the incision axis, and the axis where the proximal ends of the ICRS should be located according to the preoperative planning. We compared the post-operative alignment with the Goniotrans software in 10 patients operated with this system and 10 patients with the standard manual marking procedure.


We could obtain a good quality intra-operative eye-image captures in all the 10 patients studied. Intraoperative cyclotorsion was compensated by manually rotating the suction cone to the previously marked horizontal axis. The mean deviation of the incision axis was 5�Â�º�Â�±4 in the Verion�â�„�¢ group and 10�Â�º�Â�±6 in the manual group. The mean difference between the planned and final positioning of the ICRS was more precise with the Verion�â�„�¢ group but statistically non significant.


Surgical procedure of implantation of ICRS for treating keratoconus and other corneal ectasias is yet an inaccurate surgery regarding positioning of the segments and relies in the surgeon experience and manual marking and planning of the surgery. Changes in the desired position of the ICRS may lead undesired overcorrections or undercorrections of the refractive error as well as the optical aberrations. Improving the precision of the ICRS alignment according to the preoperative planning and nomograms may help us in better understanding and improving the results of the technique.

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