Aberrations induced in wavefront-guided laser refractive surgery due to shifts between natural and dilated pupil center locations

Porter, Jason; Yoon, Geunyoung; Lozano, Diana C; Wolfing, Jessica I.; Tumbar, Remy; MacRae, Scott; Cox, Ian; Williams, David R.

doi:10.1016/j.jcrs.2005.10.027

Cited by 74 publications

(43 citation statements)

References 27 publications

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“…Registration should involve orientations in the x- and y-planes to compensate for pupil centroid shifts and cyclotorsional displacement occurring between wavefront measurement and laser procedure, which can be expected to improve safety and effectiveness of wavefront-guided refractive surgery. The potential impact of misalignment is undercorrection of astigmatism and insufficient correction of HOAs [8,9,10,11,12,13,14]. …”

Section: Discussionmentioning

confidence: 99%

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Measurement of Pupil Centroid Shift and Cyclotorsional Displacement Using Iris Registration

2009

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Background/Aims: To estimate the amount and nature of pupil centroid shift and cyclotorsion occurring between preoperative wavefront measurement and refractive surgery. Methods: This retrospective study comprised 183 eyes of 92 patients who had wavefront-guided LASIK using iris registration. We analyzed the pupil centroid shift and cyclotorsional displacement occurring between preoperative wavefront measurements and during the laser procedure. The eyes were measured by the WaveScan® Wavefront® system (VISX, Santa Clara, Calif., USA) and refractive surgery was performed with the VISX STAR S4 excimer laser system. Results: The mean magnitude of shifts in the location of pupil center was 0.26 ± 0.16 mm horizontally, 0.20 ± 0.16 mm vertically and 0.37 ± 0.13 mm vectorally. 162 eyes (88.5%) experienced more than 0.2 mm of shift. The mean amount of torsion was 2.58 ± 1.56° for 83 eyes showing incyclotorsion and 2.94 ± 1.87° for 100 eyes showing excyclotorsion. 117 eyes (63.9%) experienced more than 2° of cyclotorsion and 21 eyes (11.5%) experienced more than 5° of cyclotorsion. Conclusions: Pupil centroid shift and cyclotorsion occur in the majority of eyes undergoing laser treatment. The amount of pupil centroid shift and cyclotorsion shown in this study is considerable. Accurate compensation for cyclotorsion and pupil centroid shift may maximize the potential of visual quality of customized ablations.

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Section: Discussionmentioning

confidence: 99%

“…The pupil centroid shifts that occur with different levels of illumination have been studied [1,2,3,9,10,11]. Yang et al [1 ]reported that the average pupil center shift from mesopic to photopic lighting conditions was 0.054 mm nasally and 0.004 mm superiorly.…”

Section: Discussionmentioning

confidence: 99%

Measurement of Pupil Centroid Shift and Cyclotorsional Displacement Using Iris Registration

2009

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“…But, as for Thibos et al's study, 4 a possible factor might be that their subject's pupil was dilated while we tested the natural pupil. After dilation, the pupil center could be shifted [31][32][33][34][35] and become closer to the line of sight. This shift of the pupil center toward the line of sight could make the structure of higher-order aberrations more symmetrical with respect to the line of sight, thus systematically reducing the values associated to the asymmetric higherorder aberrations of the population under study.…”

Section: Discussionmentioning

confidence: 99%

Higher-Order Wavefront Aberrations for Populations of Young Emmetropes and Myopes

Bao

et al. 2009

Journal of Optometry

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PURPOSE:To test the hypothesis that human eyes have a central tendency to be free of higher-order aberrations by analyzing wavefront aberrations for two young populations of respectively emmetropic and myopic subjects. METHODS: Both right and left eyes of 75 emmetropes and 196 myopes were measured for corneal wavefront aberration using a Humphrey corneal topographer and for the whole eye wavefront aberration using a WASCA wavefront sensor without pupil dilation. 35 Zernike aberration coefficients over a 6.0 mm pupil diameter were derived, and statistics of the higher-order terms (3 rd to 5 th orders) were tested. RESULTS: When signed Zernike aberrations of the right and left eyes were averaged together for the emmetropes, three higher-order modes (j=6, 12 and 13) were significantly different from zero in both the cornea and the whole eye (P<0.0005), and three additional terms (j=14, 15 and 17) were statistically non-zero for the whole eye. As the signs of y-axis asymmetrical terms in the left eye were flipped, three more terms in either the cornea (j=8, 18 and 19) or the whole eye (j=8, 10 and 20) became statistically non-zero. For the myopes, 8 corneal terms and 5 whole-eye terms were statistically non-zero when the two eyes were averaged together. As the signs flipped, the majority of the Zernike aberration terms were statistically different from zero. CONCLUSIONS: Human eyes have systematical higher order aberrations in population, and factors that cause bilateral symmetry of wavefront aberrations between the right and left eyes made important contribution to the systematical aberrations. (J Optom 2009;2:51-58 ©2009 Spanish Council of Optometry)

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“…Fluctuation due to accommodation [37], tear film changes [21] and potential misalignment of the measurement system [32] might lead to high intra-individual variations. Furthermore, shifts in pupil center location from when aberrations are measured preoperatively (over a dilated pupil) to when they are corrected surgically (over a natural pupil) led to the induction of HOA [44].…”

Section: Issues To Be Solvedmentioning

confidence: 99%

The future role of wavefront-guided excimer ablation

Kohnen

Kühne

Bühren

2006

Graefe's Arch Clin Exp Ophthalmol

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Aberrations induced in wavefront-guided laser refractive surgery due to shifts between natural and dilated pupil center locations

Cited by 74 publications

References 27 publications

Measurement of Pupil Centroid Shift and Cyclotorsional Displacement Using Iris Registration

Measurement of Pupil Centroid Shift and Cyclotorsional Displacement Using Iris Registration

Higher-Order Wavefront Aberrations for Populations of Young Emmetropes and Myopes

The future role of wavefront-guided excimer ablation

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