Analysis of Astigmatic Keratotomy With a 5.0-mm Optical Clear Zone

Chavez, Salvador; Chayet, Arturo; Celikkol, Leyla; Parker, J.; Celikkol, Gurkan; Feldman, Sandy T.

doi:10.1016/s0002-9394(14)70535-5

Cited by 19 publications

(3 citation statements)

References 15 publications

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“…Laser surgery is limited in terms of correction of high myopia and high astigmatism, 17,18 and is also associated with the complications common to keratorefractive procedures (corneal ectasia, regression, poor quality of dark vision), likely caused by changes in corneal contours. 19,20 Toric pIOL implantation is not associated with such complications, and can correct high astigmatism regardless of corneal thickness.…”

Section: Discussionmentioning

confidence: 99%

Comparison of patient outcomes after implantation of Visian toric implantable collamer lens and iris-fixated toric phakic intraocular lens

Lee

Ahn

et al. 2011

Eye

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Purpose We compared visual and refractive outcomes after implantation of Visian toric implantable collamer lenses (toric ICLs) and iris-fixated toric pIOLs (toric Artisans). Patients and methods A comparative retrospective analysis was performed. Toric ICLs were implanted into 30 eyes of 18 patients, and toric Artisans into 31 eyes of 22 recipients. We measured the logarithms of the minimum angle of resolution of uncorrected visual acuity (logMAR UCVA), logMAR of best spectaclecorrected corrected VA (logMAR BSCVA), MR, SE, and astigmatism (by the power vector method) before surgery and 1, 3, and 6 months thereafter. Differences between patients receiving each type of lens were compared by using a mixed model of repeated measures. Results Visual improvements were evident after operation in both groups. By comparing the attempted to the achieved SE values, we were able to confirm that correction of refractive error was similar in both groups. However, the logMAR UCVA was significantly higher in the toric ICL group at all postoperative time points. Although manifest cylinder power and astigmatism (calculated by using the power vector method) gradually decreased in the toric ICL group, cylinder power 1 month postoperatively increased from À2.62 to À2.75 D; astigmatism was also increased at this time in the toric Artisan group. Conclusion The two tested toric pIOLs were similar in terms of the ability to correct refractive error, as assessed 3 months postoperatively. However toric ICLs corrected astigmatism more rapidly and safely. Notably, the large difference in astigmatism level between the two groups 1 month postoperatively indicates that toric ICLs are more effective when used to correct astigmatism.

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Section: Discussionmentioning

confidence: 99%

Comparison of patient outcomes after implantation of Visian toric implantable collamer lens and iris-fixated toric phakic intraocular lens

Lee

Ahn

et al. 2011

Eye

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“…Thornton's technique involved making paired arcuate incisions placed at the 7.0 mm and 8.0 mm optical zones, following a curve on the cornea, while Chayez et al recommended optical zone sizes as small as 5.0 mm. 26, 37 Nichamin developed an extensive nomogram for AK at the time of cataract surgery;titled"Intralimbal relaxing incision nomogram for modern phaco surgery," which has age adjustments for correction of against-the-rule astigmatism and with-the-rule astigmatism. It utilizes an empiric blade-depth setting of 600 μm.…”

Section: Introductionmentioning

confidence: 99%

Surgical Correction of Astigmatism During Cataract Surgery

Çömez¹,

Özkurt²

2012

Astigmatism - Optics, Physiology and Management

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Astigmatism -Optics, Physiology and Management 294Refractive astigmatism; also called total astigmatism; as determined by retinoscopy or by s u b j e c t i v e r e f r a c t i o n , i s m a d e u p o f both corneal and internal astigmatism. Corneal astigmatism occurs due to unequal curvature along the two principal meridians of the anterior cornea and internal astigmatism is due to factors such as the toricity of the posterior surface of the cornea, unequal curvatures of the front and back surfaces of the crystalline lens, or tilting of the crystalline lens with respect to the optic axis of the cornea. The combination of the corneal and the internal astigmatism gives the eye's total(refractive) astigmatism. Corneal astigmatism is often classified according to the axis of astigmatism as being either with-the rule (WTR), oblique or against-the-rule (ATR). It is well accepted that there is some relationship between the eye's corneal and internal astigmatism. In 1890, Javal proposed a rule that predicted the refractive (total) astigmatism of the eye based on the corneal astigmatism.10 Javal's rule states: A t =k + p(A c ) where A t is the refractive (total) astigmatism and A c is the corneal astigmatism. The terms k and p are constants approximated by 0.5 and 1.25, respectively. This rule relies on the fact that residual astigmatism is thought to be constant and ATR in most people (that is, -0.50 D ATR). Keller and colleagues investigated the relationship between corneal and total astigmatism by measuring corneal astigmatism with a computer-assisted videokeratoscope and the results from this study supported Javal's rule.11 To quantify the discrepancy between corneal and refractive astigmatism measurements, the corneal astigmatism value measured by topography or keratometry is substracted from the refractive cylinder measured by wavefront or manifest refraction and the vectorial difference is known as the ocular residual astigmatism (ORA), which is expressed in diopters.12,13 Keratometry, topography, and refraction, all provide useful information regarding the astigmatic status of patients. If the astigmatism measured by these tools is not in agreement either in magnitude, axis, or both, then the surgeon needs to evaluate all the datas again in order to optimise the visual outcome. Corneal topography provides a qualitative and quantitative image map based on evaluation of the corneal curvature14. Most topographers evaluate 8,000 to 10,000 specific points over the entire cornea and center the acquisition on the corneal apex. Topographers that incorporate scanning slit photography also measure the power and the astigmatism of the posterior corneal surface, which may improve correlation with the refractive astigmatism.15 In contrast to topography measurements, manual keratometry has only four data points within 3 mm to 4 mm of the central anterior surface of the cornea. An other device, automated keratometer, although not sensitive for accuracy of axis with low magnitudes of astigmatism, may be useful in screening astig...

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“…Έηζη ινηπφλ νη ηνμνεηδείο ηνκέο ζρεηίδνληαη κε ζρεηηθά πςειφηεξν αζηηγκαηηζκφ, νη επζείεο ηνκέο κε κέηξην, νη θακπχιεο ζεσξνχληαη αζηηγκαηηθά νπδέηεξεο (εηθφλα 11).Ζ κνληέξλα κηθξήο ηνκήο επέκβαζε ηνπ θαηαξξάθηε έρεη βειηησκέλα απνηειέζκαηα φζνλ αθνξά ην ζθαίξσκα θαη ηνλ αζηηγκαηηζκφ. Παξ"φηη ε θαθνζξπςία κε ηνκή 23.3.1 Σνκέο επί ηνπ θπξηόηεξνπ άμνλα (on-axis) θαη θαηά δεύγε αληίζεηεο ηνκέο (opposite clear corneal incisions-OCCI's)Καηά ηε δηάξθεηα ηεο επέκβαζεο ηνπ θαηαξξάθηε είλαη δπλαηφ λα κεηψζνπκε ηνλ πξνεγρεηξεηηθφ αζηηγκαηηζκφ ηξνπνπνηψληαο ην ζρήκα, ην εχξνο, ηνλ ηχπν θαη ηελ εληφπηζε ηεο ηνκήο 204,205,208,211,214,[222][223][224][225][226][227][228]. Ο απινχζηεξνο ηξφπνο γηα λα γίλεη απηφ είλαη ε εθαξκνγή θαζαξά θεξαηηθήο ηνκήο ζηνλ θπξηφηεξν θεξαηηθφ άμνλα είηε απηφ είλαη άλσ, θξνηαθηθά ή πιάγηα έηζη ψζηε λα επηπεδσζεί ν άμνλαο επί ηνπ νπνίνπ εθηειείηαη (on-axis ηνκή).…”

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Επίδραση της βοηθητικής τομής (sideport) στη διάθλαση του οφθαλμού μετά από επέμβαση καταρράκτη

Theodoulidou¹,

Θεοδουλίδου²

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Σκοπός: η μελέτη των αλλαγών του κερατοειδικού αστιγματισμού μετά από επέμβαση καταρράκτη, σε όταν η βοηθητική τομή (sideport) εκτελείται σε ορισμένη απόσταση από την κύρια τομή (tunnel). Υλικό και μέθοδος: 333 οφθαλμοί με κερατοειδικό αστιγματισμό ≤1,5 διοπτρίες (D) υποβλήθηκαν σε επέμβαση καταρράκτη. Μια 3-βημάτων, 3.0mm, άνω κροταφική, καθαρά κερατική κύρια τομή στους δεξιούς οφθαλμούς και άνω ρινική καθαρά κερατική κύρια τομή στους αριστερούς οφθαλμούς, εκτελούνταν, ενώ η βοηθητική τομή εντοπιζόταν σε απόσταση ≤95°, 100°-110° και 110° από την κύρια τομή. Οι κερατομετρικές ενδείξεις μετρήθηκαν σε τοπογραφία κερατοειδή EyeSys Vista 2000 προ- και μετεγχειρητικά τον 1ο και 6ο μήνα. Ο χειρουργικά προκαλούμενος αστιγματισμός (surgically induced astigmatism-SIA) υπολογίστηκε με διανυσματική ανάλυση. Μελετήθηκαν οι περιπτώσεις που παρουσίαζαν αλλαγή την ισχύος του αστιγματισμού >0,5D, καθώς και οι περιπτώσεις με αλλαγή >20° στον άξονα του αστιγματισμού, ανεξάρτητα από την κατεύθυνση της κλίσης. Αποτελέσματα: τα αποτελέσματα αναλύθηκαν με τη μέθοδο πολυπαραγοντικής λογαριθμιστικής παλινδρόμησης με εξαρτημένη μεταβλητή. Στις περιπτώσεις >110° απόστασης μεταξύ κύριας και βοηθητικής τομής υπήρξε 2,22 φορές (p=0,021) μεγαλύτερη πιθανότητα αλλαγής >0,5D της αστιγματικής ισχύος τον 1ο μετεγχειρητικό μήνα και 3,45 φορές (p=0,031) μεγαλύτερη πιθανότητα αλλαγής της ισχύος, τον 6ο μετεγχειρητικό μήνα, σε σύγκριση με τις περιπτώσεις με απόσταση μεταξύ των δύο τομών 100-110°. Ως προς την αλλαγή του άξονα του αστιγματισμού, στις περιπτώσεις ≤95° απόστασης μεταξύ των δύο τομών, υπήρχε 4,18 φορές μεγαλύτερη πιθανότητα αλλαγής >20° (p<0,001) τον 1ο μετεγχειρητικό μήνα σε σύγκριση με τις περιπτώσεις με απόσταση 100-110°. Συμπέρασμα: για τους χειρουργούς που χειρουργούν άνωθεν της κεφαλής του ασθενή, προκειμένου να έχουν κατά το δυνατόν «αστιγματικά ουδέτερες» τομές να εκτελούν την βοηθητική τομή σε απόσταση 100-110° από την κύρια τομή.

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Analysis of Astigmatic Keratotomy With a 5.0-mm Optical Clear Zone

Cited by 19 publications

References 15 publications

Comparison of patient outcomes after implantation of Visian toric implantable collamer lens and iris-fixated toric phakic intraocular lens

Comparison of patient outcomes after implantation of Visian toric implantable collamer lens and iris-fixated toric phakic intraocular lens

Surgical Correction of Astigmatism During Cataract Surgery

Επίδραση της βοηθητικής τομής (sideport) στη διάθλαση του οφθαλμού μετά από επέμβαση καταρράκτη

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