Calculation of total surgically induced astigmatism with a toric intraocular lens

2020 ◽  
Vol 46 (5) ◽  
pp. 793-794 ◽  
Author(s):  
Jack T. Holladay
Keyword(s):  
Intraocular Lens ◽  
Toric Intraocular Lens ◽  
Surgically Induced Astigmatism ◽  
Induced Astigmatism ◽  
Surgically Induced

scholarly journals Comparison of surgically induced astigmatism between anterior and total cornea in 2.2 mm steep meridian incision cataract surgery

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Young-chae Yoon ◽  
Minji Ha ◽  
Woong-Joo Whang
Keyword(s):  
Cataract Surgery ◽  
Intraocular Lens ◽  
Corneal Surface ◽  
Polar Plot ◽  
Mean Values ◽  
Surgically Induced Astigmatism ◽  
Induced Astigmatism ◽  
The Mean ◽  
Surgically Induced ◽  
Corneal Refractive Power

Abstract Background This study aimed to compare surgically induced astigmatism (SIA) on the anterior and total cornea during cataract surgery through a 2.2 mm steep meridian incision. Methods The study included 69 left eyes of 69 patients who had undergone cataract surgery. The 69 eyes were classified into three subgroups according to the preoperative steep meridian. Following phacoemulsification, an intraocular lens was inserted into the bag. The keratometric measurements were taken 12 months postoperatively, on the anterior cornea (automated keratometer and anterior keratometry [K] from a rotating Scheimpflug camera) and total cornea (equivalent K reading [EKR] 3.0 mm, EKR 4.5 mm, total corneal refractive power (TCRP) 2.0 mm ring, TCRP 3.0 mm zone, TCRP 4.0 mm zone). The SIA was analyzed for each parameter. Results On the double-angle polar plot, the summated vector mean values of SIA determined by the automated keratometer and Scheimpflug anterior K were 0.28 diopter (axis: 177°) and 0.37 diopter (axis: 175°) in with-the-rule (WTR) astigmatism; 0.03 diopter (axis: 156°) and 0.18 diopter (axis: 177°) in oblique astigmatism; 0.15 diopter (axis: 96°) and 0.17 diopter (axis: 73°) in against-the-rule (ATR) astigmatism. The mean SIAs on the total cornea ranged from 0.31 to 0.42 diopter in WTR astigmatism; from 0.16 to 0.27 diopter in oblique astigmatism; from 0.04 to 0.11 diopter in ATR astigmatism. Mean magnitude SIA ranged from 0.41 to 0.46 diopter on anterior corneal surface and 0.50 to 0.62 diopter on total cornea. J0 and J45 of the posterior cornea showed no significant changes after cataract surgery, and the changes in J0 and J45 did not show any statistical differences between the anterior and total cornea (all p > 0.05). Conclusions There were no differences in the summed vector mean values of SIA between the anterior cornea and the total cornea.

scholarly journals Prediction of surgically induced astigmatism in manual and femtosecond laser-assisted clear corneal incisions

2018 ◽  
Vol 28 (4) ◽  
pp. 398-405 ◽  
Author(s):  
Joaquín Fernández ◽  
Manuel Rodríguez-Vallejo ◽  
Javier Martínez ◽  
Ana Tauste ◽  
David P Piñero
Keyword(s):  
Femtosecond Laser ◽  
Corneal Astigmatism ◽  
Toric Intraocular Lens ◽  
Surgically Induced Astigmatism ◽  
Orthogonal Components ◽  
Induced Astigmatism ◽  
The Mean ◽  
Surgically Induced ◽  
Corneal Incisions ◽  
Intraocular Lens Calculation

Purpose: To assess the surgically induced astigmatism with femtosecond laser-assisted and manual temporal clear corneal incisions and to evaluate the performance of a model for prediction of the surgically induced astigmatism based on the preoperative corneal astigmatism. Methods: Clinical data of 104 right eyes and 104 left eyes undergoing cataract surgery, 52 with manual incisions and 52 with femtosecond laser-assisted incisions in each eye group, were extracted and revised retrospectively. In all cases, manual incisions were 2.2 mm width and femtosecond incisions were 2.5 mm width, both at temporal location. A predictive model of the surgically induced astigmatism was obtained by means of simple linear regression analyses. Results: Mean surgically induced astigmatisms for right eyes were 0.14D@65° (manual) and 0.24D@92° (femtosecond) (p > 0.05) and for left eyes, 0.15D@101° (manual) and 0.19D@104° (femtosecond) (p > 0.05). The orthogonal components of the surgically induced astigmatism (XSIA, YSIA) were significantly correlated (p < 0.05) with the preoperative orthogonal components of corneal astigmatism (Xpreop, Ypreop) (r = −0.29 for X and r = −0.1 for Y). The preoperative astigmatism explained 8% of the variability of the XSIA and 3% of the variability of YSIA. The postoperative corneal astigmatism prediction was not improved by the surgically induced astigmatism obtained from the model in comparison with the simple vector subtraction of the mean surgically induced astigmatism. Conclusion: Temporal incisions induce similar astigmatism either for manual or for femtosecond procedures. This can be clinically negligible for being considered for toric intraocular lens calculation due to the great standard deviation in comparison with the mean. The usefulness of the prediction model should be confirmed in patients with high preoperative corneal astigmatism.

Prewound Assisted Technique for Hydrophobic Foldable Intraocular Lens Implantation

2017 ◽  
Vol 27 (5) ◽  
pp. 569-572
Author(s):  
Takuya Shiba ◽  
Hiroshi Tsuneoka
Keyword(s):  
Intraocular Lens ◽  
The Other ◽  
Implantation Technique ◽  
Iol Implantation ◽  
Surgically Induced Astigmatism ◽  
Small Incision ◽  
Lens Implantation ◽  
Before And After ◽  
Induced Astigmatism ◽  
Surgically Induced

Purpose To describe a technique for intraocular lens (IOL) implantation that lessens the degree of surgical invasiveness by implanting a tightly rolled IOL through a small incision without touching the eye with the cartridge tip. Methods An IOL was inserted through an incision by first allowing the leading haptic to protrude slightly from the cartridge tip. It was then injected through the incision without allowing any part of the cartridge to touch the eye during IOL implantation. In one eye, the entire circumference of the beveled portion of the cartridge tip was inserted into the anterior chamber to implant the IOL, whereas in the other eye, the IOL was inserted through the incision by first allowing the leading haptic to protrude slightly from the cartridge tip. It was then injected through the incision without allowing any part of the cartridge to touch the eye during IOL implantation. We analyzed the incision width before and after IOL implantation and the degree of surgically induced astigmatism on the day after surgery and at 1 and 3 months after surgery. Results Using our technique, both the amount by which the wound was enlarged and the hydration rate were significantly lower compared with conventional IOL implantation. Our method enables IOL implantation to be carried out through a small incision at a width that was only previously possible with forcible insertion. Conclusions Our IOL implantation technique can be performed using both hands with no need to immobilize the eyeball.

scholarly journals Comparison of magnitude and summated vector mean of surgically induced astigmatism vector according to incision site after phakic intraocular lens implantation

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Kazutaka Kamiya ◽  
Wakako Ando ◽  
Masahide Takahashi ◽  
Nobuyuki Shoji
Keyword(s):  
Intraocular Lens ◽  
Medical Information ◽  
Corneal Astigmatism ◽  
University Hospital ◽  
Rank Test ◽  
Phakic Intraocular Lens ◽  
Surgically Induced Astigmatism ◽  
Incision Site ◽  
Induced Astigmatism ◽  
Surgically Induced

Abstract Background To compare the arithmetic mean (M-SIA) and the summated vector mean of surgically induced astigmatism (SVM-SIA) according to the incision site after phakic intraocular lens (Visian implantable collamer lens (ICL), STAAR Surgical) implantation. Methods This study comprised 121 eyes of 121 consecutive patients undergoing ICL surgery through a 3.0-mm temporal or superior clear corneal incision. The magnitude and the axis of corneal astigmatism preoperatively and 3 months postoperatively were measured using an automated keratometer. The M-SIA and the SVM-SIA were determined according to the incision site. Results The magnitude of corneal astigmatism significantly increased from 1.23 ± 0.59 D preoperatively to 1.46 ± 0.72 D postoperatively in the temporal incision group (Wilcoxon signed-rank test, P < 0.001), but it significantly decreased from 1.09 ± 0.36 D preoperatively to 0.86 ± 0.41 D postoperatively in the superior incision group (P < 0.001). The M-SIA was 0.48 ± 0.30 D, and the SVM-SIA was 0.23 ± 0.52 D at a meridian of 82° in the temporal incision group. The M-SIA was 0.57 ± 0.30 D, and the SVM-SIA was 0.47 ± 0.45 D at a meridian of 1° in the superior incision group. Conclusions ICL implantation induces the M-SIA by approximately 0.5 D, but the SVM-SIA decreased to 50% and 80% of the M-SIA in magnitude through temporal and superior incisions, respectively. The direction of the SVM-SIA showed a tendency toward corneal flattening to the incisional site. It should be noted that the M-SIA is somewhat different from the SVM-SIA according to the incision site. Trial registration University Hospital Medical Information Network Clinical Trial Registry (000044269)

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