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Correlation between iris-registered static and dynamic cyclotorsions with preoperative refractive astigmatism in refractive surgery candidates

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Session Details

Session Title: Presented Poster Session 11: Refractive Surgery New Techniques / Instrumentation / Devices 1

Session Date/Time: Sunday 14/09/2014 | 15:00-17:00

Paper Time: 15:00

Venue: Pod 2 (Poster Village)

First Author: : M.Mohammadpour IRAN

Co Author(s): :    H. Hashemi   M. Jabbarvand   N. Chiniforoush        

Abstract Details


To evaluate measurement of static and dynamic cyclotorsions during laser excimer( PRK) surgery in refractive surgery candidates and their correlation with preoperative factors, especially refractive astigmatism.


Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran


The measurements of static and dynamic cyclotorsions were registered in 138 eyes of 77 patients who underwent excimer laser system by Technolas 217z100. Wavefront measurements were performed in sitting position using Hartmann Shack aberrometer (Bausch & Lomb) and compared with the amount of cyclotorsion in supine position using the iris registration system of Zyoptix 217z100 excimer laser resulted static cyclotorsion. Dynamic cyclotorsions were measured by ACE (Advanced Cyclotorsional Eye Tracker) mounted on Excimer laser machine Technolos 217Z during surgery. Pearson's correlation was used to find significant correlation between predictive factors such as preoperative refractive astigmatism and torsional movements.


The mean absolute static cyclotorsion was 3.372.38SD, (range from 0.00 to 11.30 degrees) and the mean absolute dynamic cyclotorsion was 2.54 2.50(SD) degrees (range 0.00 to 13.60). There was a significant relationship between dynamic cyclotorsions and static cyclotorsions (p-value<0.000 and Pearson’s correlation 0.704). There was strong association between preoperative refractive astigmatism and mean dynamic cyclotorsion. Total pulses, ablation depth and hyperopic refractive errors had significant correlation with cyclotorsional movements.


Most of cyclotorsional errors were between 2 degrees shifts. Amount of dynamic and static cyclotorsions depends on total pulses, length of surgery and hyperopic refraction further more there were significant dynamic cyclotorsions with high astigmatism. Iris Registration especially dynamic eye tracking is recommended for refractive surgery candidates with significant preoperative refractive astigmatism and/or hyperopic correction.

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