scholarly journals Effect of Trabeculectomy on Mean and Centroid Surgically Induced Astigmatism

2022 ◽  
Vol 11 (1) ◽  
pp. 240
Author(s):  
Wakako Ando ◽  
Kazutaka Kamiya ◽  
Masayuki Kasahara ◽  
Nobuyuki Shoji
Keyword(s):  
Arithmetic Mean ◽  
Corneal Astigmatism ◽  
Scleral Flap ◽  
Surgically Induced Astigmatism ◽  
Induced Astigmatism ◽  
The Right ◽  
Surgically Induced ◽  
Paired T Test ◽  
Flap Creation

This study aimed to investigate the arithmetic mean of surgically induced astigmatism (M-SIA) and the centroid of surgically induced astigmatism (C-SIA) after standard trabeculectomy. We comprised 185 eyes of 143 consecutive patients (mean age ± standard deviation, 67.7 ± 11.6 years) who underwent trabeculectomy and completed at least a 3-month routine follow-up. In all cases, the scleral flap was made at the nasal-superior location. Corneal astigmatism was measured with an automated keratometer. We calculated the M-SIA and the C-SIA using vector analysis and applied the astigmatism double angle plot. The magnitude of corneal astigmatism increased significantly, from 1.17 ± 0.92 D preoperatively to 1.77 ± 1.05 D postoperatively (paired t-test, p < 0.001). The M-SIA was 1.12 ± 0.55 D, and the C-SIA was 0.73 D @64° ± 1.02 D in the right eye group, and the M-SIA was 1.08 ± 0.48 D and the C-SIA was 0.60 D @117° ± 1.03 D in the left eye group. The C-SIA showed an astigmatic shift toward the nasal-superior location of the scleral flap creation. Our results revealed that trabeculectomy induced the SIA in the direction of the scleral flap location and that the C-SIA was much lower than the M-SIA in eyes undergoing trabeculectomy.

scholarly journals Comparison of Mean and Centroid of Surgically Induced Astigmatism After Standard Cataract Surgery

2021 ◽  
Vol 8 ◽  
Author(s):  
Kazutaka Kamiya ◽  
Kei Iijima ◽  
Wakako Ando ◽  
Nobuyuki Shoji
Keyword(s):  
Cataract Surgery ◽  
Arithmetic Mean ◽  
Corneal Astigmatism ◽  
Corneal Incision ◽  
Surgically Induced Astigmatism ◽  
Clear Corneal Incision ◽  
Induced Astigmatism ◽  
The Individual ◽  
The Right ◽  
Surgically Induced

Purpose: To compare the arithmetic mean of surgically induced astigmatism (M-SIA) and the centroid of surgically induced astigmatism (C-SIA) after standard cataract surgery.Methods: We retrospectively examined 200 eyes of 100 consecutive patients undergoing bilateral cataract surgery through a 2.8 mm temporal clear corneal incision. We quantitatively measured the magnitude and axis of corneal astigmatism preoperatively and 3 months postoperatively using an automated keratometer (TONOREFF-II, Nidek). We assessed the M-SIA, the C-SIA, and the double angle plots for the display of the individual SIA distributions.Results: For bilateral data analysis, the magnitude of corneal astigmatism significantly increased from 0.66 ± 0.39 D preoperatively to 0.74 ± 0.46 D postoperatively (paired t-test, p = 0.012). The M-SIA was 0.50 ± 0.36 D. On the other hand, the C-SIA was 0.18 ± 0.60 D at an axis of 97°. For unilateral analysis, we obtained similar outcomes between the right and left eye groups.Conclusions: According to our experience, standard cataract surgery induces the M-SIA by approximately 0.5 D. The magnitude of the C-SIA largely decreased to approximately 40% of the M-SIA, and the direction of the C-SIA showed a tendency toward with-the-rule astigmatism. It should be noted that the M-SIA was considerably different from the C-SIA, especially when selecting the appropriate toric IOL model and power.

scholarly journals Astigmatism Correction during Femtosecond Laser-assisted Transepithelial Arcuate Keratotomy Using the Wound Open Method

2021 ◽  
Vol 62 (12) ◽  
pp. 1592-1599
Author(s):  
Joon Kyo Chung ◽  
Gyu Le Han ◽  
Hoon Noh ◽  
Dong Hui Lim ◽  
Tae-Young Chung
Keyword(s):  
Femtosecond Laser ◽  
Medical Center ◽  
Corneal Astigmatism ◽  
Retrospective Survey ◽  
Surgically Induced Astigmatism ◽  
Open Method ◽  
Astigmatism Correction ◽  
Before And After ◽  
Induced Astigmatism ◽  
Surgically Induced

Purpose: The purpose of this study was to compare corneal astigmatism correction between “wound open” and “wound intact” methods during femtosecond laser-assisted transepithelial arcuate keratotomy.Methods: From April 2016 to December 2018, a retrospective survey was conducted on patients undergoing femtosecond laser cataract surgery at the Ophthalmology Department of Samsung Medical Center. Size comparison and vector analysis of corneal astigmatism before and after surgery were performed in the wound open and wound intact groups.Results: In the wound open and wound intact groups, the target-induced astigmatism (TIA) was 1.28 ± 0.55; and 1.26 ± 0.29 diopters, the surgically induced astigmatism (SIA) was 0.80 ± 0.52; and 0.53 ± 0.32 diopters, and the correction index (CI) was 0.63 ± 0.28; and 0.43 ± 0.26, respectively. The astigmatism correction was superior in the wound open group (p = 0.048, p = 0.025). In a subgroup with TIA < 1.2 diopters, there were no significant differences in SIA or CI between the two groups; however, in the subgroup with a TIA > 1.2 diopters, the SIA was 1.09 ± 0.59; and 0.54 ± 0.37 diopters and the CI was 0.60 ± 0.28; and 0.36 ± 0.23 in the wound open and wound intact groups, respectively (p = 0.022, p = 0.047). Thus, astigmatism correction was superior in the wound open group.Conclusions: The wound open method during femtosecond laser-assisted transepithelial arcuate keratotomy was superior for astigmatism correction compared to the wound intact method.

Comparison of using Galilei Dual Scheimpflug Analyzer G4 and Barrett formula in predicting low cylinder preoperatively for cataract surgeries

2019 ◽  
Vol 30 (6) ◽  
pp. 1320-1327
Author(s):  
Yi-Ju Ho ◽  
Chi-Chin Sun ◽  
Jiahn-Shing Lee ◽  
Ken-Kuo Lin ◽  
Chiun-Ho Hou
Keyword(s):  
Cataract Surgery ◽  
Absolute Error ◽  
Corneal Astigmatism ◽  
Intraocular Lens Implantation ◽  
Surgically Induced Astigmatism ◽  
Lens Implantation ◽  
Induced Astigmatism ◽  
Median Absolute Error ◽  
The Difference ◽  
Surgically Induced

Purpose: To compare corneal astigmatism estimation from Barrett toric calculator, with measurement from Galilei Dual Scheimpflug Analyzer G4 in low corneal cylinder patients. Methods: Preoperative corneal astigmatism was measured using Auto Kerato-Refractometer (AutoKM), IOL Master, and Galilei G4 (combined Placido-dual Scheimpflug analyzer) and was processed by Barrett toric calculator with measurements obtained from Auto Kerato-Refractometer and from IOL Master. A total of 42 eyes undergoing cataract surgery with nontoric intraocular lens implantation were included. Corneal astigmatism was calculated based on manifest refractive astigmatism with implications of surgically induced astigmatism. Errors in predicted residual astigmatism were calculated by the difference between postoperative manifest cylindrical refractive error and preoperative corneal cylinder using vector analysis. Results: Centroid error in predicted residual astigmatism was with-the-rule 0.36 D for AutoKM and 0.48 D for IOL Master, was lower at 0.24 D for the Barrett–IOL Master, and was lowest at 0.21 D for the Barrett–AutoKM ( p < .001). The Galilei G4 demonstrated the highest centroid error for SimK (0.53 D) and lower for total corneal power (0.49 D). The Barrett toric calculator obtained the lowest median absolute error in predicted residual astigmatism for AutoKM (0.43 D) and IOL Master (0.54 D). The Barrett–IOL Master demonstrated that 61% and 76% of eyes were within 0.50 and 0.75 D of the predicted residual astigmatism, respectively. Conclusion: The Barrett–IOL Master had more accurate prediction of residual astigmatism for low astigmatism eyes before cataract surgery compared to Galilei Dual Scheimpflug Analyzer G4 in this study.

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.

scholarly journals Minimizing Surgically Induced Astigmatism at the Time of Cataract Surgery Using a Square Posterior Limbal Incision

2011 ◽  
Vol 2011 ◽  
pp. 1-4 ◽  
Author(s):  
Paul Ernest ◽  
Warren Hill ◽  
Richard Potvin
Keyword(s):  
Cataract Surgery ◽  
Corneal Astigmatism ◽  
Intraocular Lenses ◽  
Corneal Incision ◽  
Surgically Induced Astigmatism ◽  
Clear Corneal Incision ◽  
Refractive Outcomes ◽  
Induced Astigmatism ◽  
Surgically Induced ◽  
Corneal Incisions

Purpose. To compare the surgically induced astigmatism from clear corneal and square posterior limbal incisions at the time of cataract surgery.Methods. Surgically induced astigmatism was calculated for a set of eyes after cataract surgery using a temporal 2.2 mm square posterior limbal incision. Results were compared to similar available data from surgeons using clear corneal incisions of similar size.Results. Preoperative corneal astigmatism averaged 1.0 D and was not significantly different between the incision types. Surgically induced astigmatism with the 2.2 mm posterior limbal incision averaged0.25±0.14 D, significantly lower in magnitude than the aggregate surgically induced astigmatism produced by the 2.2 mm clear corneal incision (0.68±0.49 D).Conclusion. The 2.2 mm square posterior limbal incision induced significantly less, and significantly less variable, surgically induced astigmatism relative to a similar-sized clear corneal incision. This is likely to improve refractive outcomes, particularly important with regard to premium intraocular lenses.

scholarly journals The effect of tunnel length and position on postoperative corneal astigmatism: An optical coherence tomographic study

2018 ◽  
Vol 30 (1) ◽  
pp. 104-111
Author(s):  
Serap Sonmez ◽  
Cagatay Karaca
Keyword(s):  
The Other ◽  
Corneal Astigmatism ◽  
Tunnel Length ◽  
Corneal Incision ◽  
Surgically Induced Astigmatism ◽  
Clear Corneal Incision ◽  
Induced Astigmatism ◽  
Short Tunnel ◽  
Surgically Induced ◽  
Corneal Incisions

Purpose: The purpose of this study is to evaluate the effects of variation in tunnel length of same-sized clear corneal phacoemulsification incisions on the generation of surgically induced astigmatism and corneal astigmatism. Methods: A total of 126 cataract patients treated in four study groups based on location and tunnel length of the clear corneal incisions (superior long, superior short, temporal long, temporal short) were reviewed. In the short tunnel groups, a 2.8 mm keratome was used with a motion parallel to the iris surface, while in the long tunnel groups, the same keratome was advanced in the corneal stroma until the mark on the keratome was reached. The surgically induced astigmatism and the corneal astigmatism were measured with corneal topography. The tunnel lengths were determined by anterior segment optical coherence tomography. Results: The tunnel lengths of the long tunnel groups were significantly longer than the short tunnel groups. The total and anterior corneal surgically induced astigmatism of the superior long group was significantly higher than the other groups. Posterior corneal surgically induced astigmatism was similar. The postoperative total and anterior corneal astigmatism values of the superior long group was significantly higher than the other groups. No difference was observed for mean change in corneal astigmatism between the groups. Conclusion: The tunnel length of a clear corneal incision is a significant determinant of surgically induced astigmatism for superior placed corneal incisions. Therefore, for superiorly positioned clear corneal incision, the incision should be rectangular with a shorter tunnel to keep the surgically induced astigmatism to a minimum. For squarer-shaped clear corneal incision, limbal-temporal incisions may be performed for astigmatic neutrality.

scholarly journals Polar Value Analysis of Low to Moderate Astigmatism with Wavefront-Guided Sub-Bowman Keratomileusis

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
Pisong Yan ◽  
Zhiyu Du ◽  
Yu Zhang
Keyword(s):  
Corneal Astigmatism ◽  
Corneal Surface ◽  
Value Analysis ◽  
Surgically Induced Astigmatism ◽  
Induced Astigmatism ◽  
A Minor ◽  
Surgically Induced ◽  
Myopic Astigmatism ◽  
Anterior Corneal Astigmatism ◽  
Posterior Corneal Astigmatism

Purpose. To evaluate the astigmatic outcomes of wavefront-guided sub-Bowman keratomileusis (WFG-SBK) for low to moderate myopic astigmatism.Methods. This study enrolled 100 right eyes from 100 patients who underwent WFG-SBK for the correction of myopia and astigmatism. The polar value method was performed with anterior and posterior corneal astigmatism measured with Scheimpflug camera combined with Placido corneal topography (Sirius, CSO) and refractive astigmatism preoperatively and 1 month, 3 months, and 6 months postoperatively.Results. Similar results for surgically induced astigmatism (SIA) and error of the procedure in both anterior corneal astigmatism (ACA) and total ocular astigmatism (TOA). There was a minor undercorrection of the cylinder in both ACA and TOA. Posterior corneal astigmatism (PCA) showed no significant change.Conclusions. Wavefront-guided SBK could provide good astigmatic outcomes for the correction of low to moderate myopic astigmatism. The surgical effects were largely attributed to the astigmatic correction of the anterior corneal surface. Posterior corneal astigmatism remained unchanged even after WFG-SBK for myopic astigmatism. Polar value analysis can be used to guide adjustments to the treatment cylinder alongside a nomogram designed to optimize postoperative astigmatic outcomes in myopic WFG-SBK.

scholarly journals Polar Value Analysis of Corneal Astigmatism in Intrastromal Corneal Ring Segment Implantation

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Chang Rae Rho ◽  
Min-Ji Kim ◽  
Choun-Ki Joo
Keyword(s):  
Corneal Astigmatism ◽  
Value Analysis ◽  
Surgically Induced Astigmatism ◽  
Corneal Power ◽  
Trace Test ◽  
Intrastromal Corneal Ring ◽  
Power Change ◽  
Ring Segment ◽  
Induced Astigmatism ◽  
Surgically Induced

Purpose.To evaluate surgically induced astigmatism (SIA) and the average corneal power change in symmetric intrastromal corneal ring segment (ICRS) implantation.Methods.The study included 34 eyes of 34 keratoconus patients who underwent symmetric Intacs SK ICRS implantation. The corneal pocket incision meridian was the preoperative steep meridian. Corneal power data were obtained before and 3 months after Intacs SK ICRS implantation using scanning-slit topography. Polar value analysis was used to evaluate the SIA. Hotelling’s trace test was used to compare intraindividual changes.Results.Three months postoperatively, the combined mean polar value for SIA changed significantly (Hotelling’sT2=0.375;P=0.006). The SIA was 1.54 D at 99° and the average corneal power decreased significantly by 3.8 D.Conclusion.Intacs SK ICRS placement decreased the average corneal power and corneal astigmatism compared to the preoperative corneal power and astigmatism when the corneal pocket incision was made at the preoperative steep meridian.

scholarly journals Effect of femtosecond laser-assisted steepest-meridian clear corneal incisions on preexisting corneal regular astigmatism at the time of cataract surgery

2020 ◽  
Vol 13 (12) ◽  
pp. 1895-1900
Author(s):  
Wei Chen ◽  
Jian Wu ◽  
Yong Wang ◽  
Jing Zhou ◽  
Rong-Rong Zhu ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Cataract Surgery ◽  
Corneal Astigmatism ◽  
Corneal Incision ◽  
Surgically Induced Astigmatism ◽  
Clear Corneal Incision ◽  
Case Series Study ◽  
Induced Astigmatism ◽  
Surgically Induced ◽  
Corneal Incisions

AIM: To investigate the clinical efficacy and safety of femtosecond laser-assisted steepest-meridian clear corneal incisions for correcting preexisting corneal astigmatism performed at the time of cataract surgery. METHODS: This prospective case series study comprised consecutive age-related cataract patients with corneal regular astigmatism (range: +0.75 to +2.50 D) who had femtosecond laser-assisted steepest-meridian clear corneal incisions (single or paired). Corneal astigmatism was performed with the Pentacam preoperatively and 3mo postoperatively. Total corneal astigmatism and steepest-meridian measured in the 3-mm central zone were used to guide the location, size and number of clear corneal incision. The vector analysis of astigmatic change was performed using the Alpins method. RESULTS: Totally 138 eyes of 138 patients were included. The mean preoperative corneal astigmatism was 1.31±0.41 D, and was significantly reduced to 0.69±0.34 D (equivalent to difference vector) after surgery (P<0.01). The surgically-induced astigmatism was 1.02±0.54 D. The correction index (ratio of target induced astigmatism and surgically-induced astigmatism: 0.72±0.36) as well as the magnitude of error (difference between surgically-induced astigmatism and target induced astigmatism: -0.29±0.51) represented a slight under correction. For angle of error, the arithmetic mean was 1.11±13.70, indicating no significant systematic alignment errors. CONCLUSION: Femtosecond-assisted steepest-meridian clear corneal incision is a fast, customizable, adjustable, precise, and safe technique for the reduction of low to moderate corneal astigmatism during cataract surgery.

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