PURPOSE To determine predictive factors for intra-operative cyclotorsion in photorefractive keratectomy (PRK). METHODS A retrospective statistical analysis of medical records pertaining to 3,996 eyes undergoing PRK was conducted. Outcome measures of this study were the likely existence of statistically significant relations between diverse and potentially influential factors and the occurrenc...

PURPOSE To evaluate the degree of static and dynamic cyclotorsion using a rotational eye tracker in laser in situ keratomileusis (LASIK) to correct myopic astigmatism. SETTING Rothschild Foundation, Paris, France. DESIGN Cohort study. METHODS Laser in situ keratomileusis with active iris registration using a Zyoptix 100 Hz excimer laser with Advanced Control Eyetracking was performed in e...

PURPOSE To report the impact of posture-related ocular cyclotorsion on one surgeon's surgically induced astigmatism (SIA) results and the variance in SIA. SETTING Institute of Eye Surgery, Whitfield Clinic, Waterford, Ireland. METHODS This prospective randomized controlled study included eyes that had phacoemulsification with intraocular lens implantation. Eyes were randomly assigned to hav...

METHODS: Assuming that cyclotorsion error can be estimated and compensated for with a certain level of uncertainty, we formulate a function to modify the wavefront error in order to minimize the residual aberration magnitudes due to cyclotorsion measurement uncertainty. A modal optimum nomogram factor is computed for minimization of the residual aberration for each Zernike mode. We also calcula...

PURPOSE To describe the theoretical effects of cyclotorted ablations on induced aberrations and determine the limits of tolerance of cyclotorsional accuracy. METHODS A method was developed to determine the average cyclotorsion during refractive surgery without a cyclotorsion tracker. Mathematical conditions were simulated to determine the optical, visual, and absolute benefits in 76 consecuti...

PURPOSE Positionally induced cyclotorsion could be an important factor concerning correction of astigmatism in refractive surgery. The method of binocular three dimensional infrared video-oculography (3D-VOG) was used to determine a possible influence of body position on cyclotorsion. METHODS 38 eyes (19 healthy subjects, median value of age 25.5) with normal binocular vision were examined us...

PURPOSE To compare refractive outcomes and higher order aberrations of eyes that underwent LASIK for myopia with astigmatism with or without active cyclotorsion error correction. METHODS This was a contralateral eye study of 48 eyes of 24 patients who underwent LASIK using the NIDEK Advanced Vision Excimer laser platform (NAVEX), treating one eye with active cyclotorsion error correction (TEC...

Head tilt and resultant ocular cyclotorsion can influence the results of ophthalmologic examinations. Thus, proper head positioning during fundus scanning has been emphasized. However, there is no perfect method to control the head tilt and little is known about the effect of small head tilts. In this study, we investigated the effect of minimal head tilt on the ocular cyclotorsion which we can...

The aim of this study was to analyse torsional optokinetic nystagmus (tOKN) in 17 patients with Menière's disease before and after (1 week, 1 month and 3 months) a curative unilateral vestibular neurotomy (UVN). The tOKN was investigated during optokinetic stimulations around the line of sight directed towards either the lesioned or the healthy side, at various constant angular velocities. Dyna...

A prospective comparative study assessing the importance of the intra-operative dynamic rotational tracking-especially in the treatment of astigmatisms in corneal refractive Excimer laser correction-concerning clinical outcomes is presented. The cyclotorsion from upright to supine position was measured using iris image comparison. The Group 1 of patients was additionally treated with cyclorotat...