Effect of Refractive and Topographic Astigmatic Axis on LASIK Correction of Myopic Astigmatism

Bragheeth, Mohamed; Dua, Harminder S.

doi:10.3928/1081-597x-20050501-10

Cited by 22 publications

(15 citation statements)

References 15 publications

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“…The results of our study are associated with an important clinical observation that is common to refractive surgeons: significant discrepancies are encountered between topographic and manifest astigmatisms during the pre-operative evaluation of the refractive patients (Mrochen et al 2003;Bragheeth & Dua 2005). Primary cause of this discrepancy is the contribution of the non-anterior refractive elements to the total astigmatic error (Alpins 1998).…”

Section: Discussionsupporting

confidence: 67%

Evaluation of the efficacy of the Allegretto Wave and the Wavefront‐optimized ablation profile in non‐anterior astigmatisms

Labiris

Gatzioufas

Giarmoukakis

et al. 2012

Acta Ophthalmologica

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. Purpose: To assess the efficacy of the Allegretto Wave and the wavefront‐optimized ablation profile (WFO) in non‐anterior astigmatism correction, in both LASIK and photorefractive keratectomy (PRK) treatments. Methods: Seventy‐four refractive surgery candidates were recruited prospectively in a non‐randomized trial. Only one eye from each candidate was randomly enrolled in the study. Of them, 40 eyes underwent LASIK treatment (LG group), while 34 eyes underwent PRK treatment (PG group). Preoperatively, the ocular residual astigmatism (ORA) was calculated for each eye, according to which each astigmatism fault was characterized as primarily anterior or non‐anterior. Twenty LG eyes and 16 PG eyes presented primarily anterior astigmatism (LG‐A and PG‐A subgroups, respectively), while 20 LG eyes and 18 PG eyes demonstrated primarily non‐anterior astigmatism (LG‐NA and PG‐NA subgroups, respectively). Postoperatively, vector analysis of astigmatism correction was conducted. The following indexes were calculated: (i) correction index (CI), (ii) difference vector (DV) and (iii) index of success (IOS). Results: Preoperatively, mean differences between manifest and topographic astigmatisms for the LG and the PG subgroups were significant (p:0.006 and p < 0.001, respectively), while postoperatively, aforementioned differences were non‐significant (p:0.18 and p:0.09, respectively). Regarding vector analysis in the LG group, mean CI, IOS and DV were 1.39 ± 1.26, 0.37 ± 1.06 and 0.30 ± 0.51, respectively. Differences in CI, IOS and DV between LG‐A and LG‐NA subgroups were non‐significant. Regarding vector analysis in the PG group, mean CI, IOS and DV were 1.22 ± 0.33, 0.47 ± 0.46 and 0.27 ± 0.25, respectively. Differences in CI, IOS and DV between PG‐A and PG‐NA subgroups were non‐significant. Conclusions: Our results suggest that the Allegretto Wave and WFO profile seem to be equally effective in both anterior and non‐anterior astigmatism correction, regardless of treatment type.

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Section: Discussionsupporting

confidence: 67%

Evaluation of the efficacy of the Allegretto Wave and the Wavefront‐optimized ablation profile in non‐anterior astigmatisms

Labiris

Gatzioufas

Giarmoukakis

et al. 2012

Acta Ophthalmologica

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“…After matching for preoperative TOA, there was still no difference in the error of treatment between the 2 groups at 6 months postoperatively. This contradicts the study of Bragheeth and Dua [ 23 ] where they found that the magnitude error of astigmatic outcomes by LASIK was greater in the disagreement group than in the agreement group (0.16 ± 0.74 versus 0.07 ± 0.52). The difference was statistically significant between the agreement group and the disagreement group.…”

Section: Discussioncontrasting

confidence: 79%

“…This difference can be explained by different ablation profiles during surgery. In our study, we performed WFG-SBK, whereas the sample of Bragheeth and Dua [ 23 ] used conventional LASIK-corrected myopic astigmatism.…”

Section: Discussionmentioning

confidence: 99%

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

Yan¹,

2017

Journal of Ophthalmology

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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.

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“…5,7−11 Most previous studies focused only on the amount of the spherical or cylindrical refraction power to correct, excluding the astigmatism axis despite its in uence on astigmatism and visual acuity after LASIK. 12 Furthermore, the linear regression analysis was generally used to select signi cant parameters highly related to the postoperative results and develop an equation in most of the previous studies. In addition, the nomogram development for SMILE has not been broadly studied yet.…”

Section: Introductionmentioning

confidence: 99%

Artificial Intelligence-Based Nomogram for Small-Incision Lenticule Extraction

Park

Kim

et al. 2020

Preprint

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Background: Small-incision lenticule extraction (SMILE) is a surgical procedure for the refractive correction of myopia and astigmatism, which has been reported as safe and effective. However, over- and under-correction still occur after SMILE. The necessity of nomograms is emphasized to achieve optimal refractive results. Ophthalmologists diagnose nomograms by analyzing the preoperative refractive data with their individual knowledge which they accumulate over years of experience. Our aim was to predict the nomograms of sphere, cylinder, and astigmatism axis for SMILE accurately by applying machine learning algorithm. Methods: We retrospectively analyzed the data of 3,034 eyes composed of four categorical features and 28 numerical features selected from 46 features. The multiple linear regression, decision tree, AdaBoost, XGBoost, and multi-layer perceptron were employed in developing the nomogram models for sphere, cylinder, and astigmatism axis. The scores of the root mean square error (RMSE) and accuracy were evaluated and compared. Subsequently, the feature importance of the best models was calculated.Results: Adaboost achieved the highest performance with an RMSE of 0.1378, 0.1166, and 5.17 for the sphere, cylinder, and astigmatism axis, respectively. The accuracies of which error below 0.25 D for the sphere and cylinder nomograms and 25° for the astigmatism axis nomograms were 0.969, 0.976, and 0.994, respectively. The feature with the highest importance was pre-operative manifest refraction for all the cases of nomograms. For the sphere and cylinder nomograms, the following highly important feature was the surgeon. Conclusions: Among the diverse machine learning algorithms, Adaboost exhibited the highest performance in prediction of the sphere, cylinder, and astigmatism axis nomograms for SMILE. The study proved the feasibility of applying artificial intelligence (AI) to nomograms for SMILE. Also it may enhance the quality of the surgical result of SMILE by providing assistance in nomograms and preventing the misdiagnosis in nomograms.

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Effect of Refractive and Topographic Astigmatic Axis on LASIK Correction of Myopic Astigmatism

Cited by 22 publications

References 15 publications

Evaluation of the efficacy of the Allegretto Wave and the Wavefront‐optimized ablation profile in non‐anterior astigmatisms

Evaluation of the efficacy of the Allegretto Wave and the Wavefront‐optimized ablation profile in non‐anterior astigmatisms

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

Artificial Intelligence-Based Nomogram for Small-Incision Lenticule Extraction

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