Cyclotorsion: A possible cause of residual astigmatism in refractive surgery

Tjon-Fo-Sang, Martha J.; Faber, Jan-Tjeerd H.N. de; Kingma, C; Beekhuis, W. H.

doi:10.1016/s0886-3350(01)01279-2

Cited by 89 publications

(69 citation statements)

References 10 publications

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“…Cyclotorsion can be due to many causes: i) positional (the eyes cyclorotate when the patient assumes a supine position), ii) secondary to head tilt (thus assuring a correct position on the laser bed is crucial), iii) unmasking of a cyclophoria (patients had a motility assessment preo peratively) following monocular occlusion (6,7) , or iv) secondary to distortion of the globe by the speculum. Compensating for the induced cyclotorsion as a result of assuming a supine position leads to better results of astigmatism correction (10)(11)(12) .…”

Section: Discussionmentioning

confidence: 99%

“…Previous reports have described the effect of centration and cyclotorsion correction on postoperative cylinder and uncorrected visual acuity (UDVA) in eyes with spherocylindrical errors of refraction (1,2,6,7) . Here we report the efficacy, reliability, and reproducibility of Static Cyclotorsion Correction (SCC) measurement using the Schwind Amaris excimer laser in eyes undergoing LASIK or t-PRK refractive surgery.…”

Section: Método: Oitenta Olhos (40 Pacientes) Todos Os Olhos Foram Smentioning

confidence: 99%

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Static cyclotorsion measurements using the Schwind Amaris laser

Fahd¹,

Jabbour²,

Fahed³

2014

Arquivos Brasileiros De Oftalmologia

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Section: Discussionmentioning

confidence: 99%

Section: Método: Oitenta Olhos (40 Pacientes) Todos Os Olhos Foram Smentioning

confidence: 99%

Static cyclotorsion measurements using the Schwind Amaris laser

Fahd¹,

Jabbour²,

Fahed³

2014

Arquivos Brasileiros De Oftalmologia

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“…[2][3][4] The stability of fixation on the horizontal and vertical plane significantly worsens through increased amounts of blur, 8 and during surface ablation the blurring of the fixation target can increase horizontal and vertical eye movements. To our knowledge, this is the first study that addresses the question of dynamic changes of eye torsion during a simulated surface ablation.…”

Section: Discussionmentioning

confidence: 99%

“…The theoretical importance of torsional misalignments can be understood if we consider that a 101 alignment error results in a 30% astigmatic, 50% trefoil and 65% tetrafoil undercorrection. 1 It has been previously reported that eye orientation significantly changes when moving from an upright to a supine position [2][3][4] and it has been postulated that this might cause errors in astigmatic correction. Relatively little is known about dynamic torsional eye movements, although torsional eye movements during fixation are believed to be significantly higher than orthogonal eye movements.…”

Section: Introductionmentioning

confidence: 99%

Cyclotorsional eye movements during a simulated PRK procedure

Fea

Sciandra

Annetta

et al. 2005

Eye

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Purpose Eye alignment is a serious concern when performing corneal surface ablation. Although several excimer lasers monitor horizontal and vertical movements, little is known about the potential impact of cyclotorsional movements. Dynamic cyclotorsions have been measured on 10 emmetropic subjects during a simulated PRK treatment. Methods Cyclotorsional eye movements were measured using a 3D videoculographic system (SMI) in 10 emmetropic subjects in upright and supine position. The subjects were wearing an eyelid speculum and were asked to fixate on a 11 red spot. The fixation target was either in focus or optically degraded by electronic filters. Data were collected at the University Eye Clinic, Torino, Italy, and the different setting measurements were compared using Student's t-test for paired data. Results Cyclotorsions were significantly higher when subjects were fixating an optically degraded stimulus (upright: P ¼ 0.04; supine: P ¼ 0.0002). The cyclotorsional movements ranged from À13 to 171. A significant difference in eye orientation was present when changing from the upright to the supine position (P ¼ 0.03). Even when correcting for this positional error, significantly higher cyclotorsional movements were detected in the supine position (in focus: P ¼ 0.0043; optically degraded: P ¼ 0.0008). The torsional range was from À14.85 to 14.551. Conclusions The high range of cyclotorsional eye movements during a simulated PRK procedure suggests that 3D tracking could improve surface ablation results when treating high astigmatism or when wavefront guided.

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“…Several papers demonstrate some dynamic compensatory movement to keep the image at the retina aligned to a natural orientation, whereas some suggestions have been made on significant cyclotorsion occurring under monocular viewing conditions 35 . Measuring rotation when the patient is upright 36 to when the refractive treatments are performed with the patient supine may lead to ocular cyclotorsion, resulting in mismatching of the applied versus the intended profiles 37 , 38 .…”

Section: Eye-trackingmentioning

confidence: 99%