Effect of corneal aberrations on intraocular lens power calculations

Cánovas, Carmen; Abenza, S.; Alcón, Encarna; Villegas, Eloy A.; Marı́n, José Marı́a; Artal, Pablo

doi:10.1016/j.jcrs.2012.03.033

Cited by 28 publications

(14 citation statements)

References 31 publications

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“…This assumption yields accurate values in normal regular corneas with minimal variations in anteroposterior corneal curvature, which was proven by ray-tracing studies. [14] Nonetheless, scarred corneas with irregular surface exhibit abnormal anteroposterior corneal curvature relation, violating the hypotheses allowing intraocular lens power calculation relying on Keratometry. Furthermore, the accuracy of measurements is frequently hindered in such irregular corneas, usually encountered after corneal refractive procedures, corneal ectasia, scarred corneas, or xerophthalmia.…”

Section: Discussionmentioning

confidence: 99%

Accuracy of intraocular lens power calculation using Scheimpflug tomography and OKULIX ray tracing software in corneal scarring

Nabil¹

2020

Preprint

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Background: To evaluate the accuracy of intraocular lens power (IOL) calculation using Scheimpflug tomography and OKULIX ray tracing software in corneal scarring. Methods: This study was conducted on 40 consecutive eyes, 20 cases with corneal scarring and coexisting cataract, and 20 controls with clear cornea, which underwent uneventful phacoemulsification and IOL implantation following Scheimpflug tomography and OKULIX ray tracing software and third generation IOL power calculation formulas for IOL power calculation. Accuracy of IOL power calculation was evaluated by subtracting expected and achieved spherical refraction 3 months postoperatively and was recorded as mean absolute error (MAE). Distance uncorrected visual acuity (UCVA) for each eye was measured using Snellen chart preoperatively and 3 months postoperatively; visual acuity was scored and converted to the logarithm of the minimum angle of resolution (LogMar).Values were recorded as mean ±SD (standard deviation). Student t-test (t) and Mann Whitney test (U) were used for parametric comparison of the means. Intra class Correlation (ICC) coefficient and Pearson correlation Coefficient (r) were used to assess agreement. A P value less than 0.05 was considered statistically significant. Results: In cases of corneal scarring, 20 eyes (100 %) yielded a postoperative spherical refraction which differed less than 1 diopter (D) from predicted, in 16 eyes (80 %) the postoperative spherical refraction was within 0.50 D from expected. The MAE was 0.2 D in cases, which did not differ significantly compared to controls (MAE 0.1 D). In corneal scarring cases, distance UCVA showed significant improvement from 1.3 Log Mar (Snellen equivalent 20/400) preoperatively to 0.5 Log Mar (Snellen equivalent 20/60) 3 months postoperatively. Conclusion: Scheimpflug tomography combined with OKULIX ray tracing software for calculation of IOL power provides accurate results in cases of corneal scarring.

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Section: Discussionmentioning

confidence: 99%

Accuracy of intraocular lens power calculation using Scheimpflug tomography and OKULIX ray tracing software in corneal scarring

Nabil¹

2020

Preprint

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Section: Discussionmentioning

confidence: 99%

Accuracy of intraocular lens power calculation using Scheimpflug tomography and OKULIX ray tracing software in corneal scarring

Nabil

2019

Preprint

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Background: To evaluate the accuracy of intraocular lens power (IOL) calculation using Scheimpflug tomography and OKULIX ray tracing software in corneal scarring. Methods: This study was conducted on 40 consecutive eyes, 20 cases with corneal scarring and coexisting cataract, and 20 controls with clear cornea, which underwent uneventful phacoemulsification and IOL implantation following Scheimpflug tomography and OKULIX ray tracing software and third generation IOL power calculation formulas for IOL power calculation. Accuracy of IOL power calculation was evaluated by subtracting expected and achieved spherical refraction 3 months postoperatively and was recorded as mean absolute error (MAE). Distance uncorrected visual acuity (UCVA) for each eye was measured using Snellen chart preoperatively and 3 months postoperatively; visual acuity was scored and converted to the logarithm of the minimum angle of resolution (LogMar). Results: In cases of corneal scarring, 20 eyes (100 %) yielded a postoperative spherical refraction which differed less than 1 diopter (D) from predicted, in 16 eyes (80 %) the postoperative spherical refraction was within 0.50 D from expected. The MAE was 0.2 D in cases, which did not differ significantly compared to controls (MAE 0.1 D). In corneal scarring cases, distance UCVA showed significant improvement from 1.3 Log Mar (Snellen equivalent 20/400) preoperatively to 0.5 Log Mar (Snellen equivalent 20/60) 3 months postoperatively. Conclusion: Scheimpflug tomography combined with OKULIX ray tracing software for calculation of IOL power provides accurate results in cases of corneal scarring.

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“…reflecting the amount of myopic correction 6,8,9 . Canovas et al 12 demonstrated that the incorporation of corneal spherical aberration at 4.0 mm was important for improving accuracy in prediction of IOL power. Mori et al 11 concluded that both Q-value and spherical aberration showed statistically significant correlations with refractive error.…”

Section: Discussionmentioning

confidence: 99%

“…Another study concluded that corneal asphericity on the anterior surface influenced the refractive outcomes calculated by the SRK/T formula in the eyes with a prior myopic LASIK history 11 . Considering corneal spherical aberration also improved the predictability of refractive outcomes in post-LASIK eyes when the ray tracing prediction was applied 12 .…”

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confidence: 99%

Influence of corneal spherical aberration on prediction error of the Haigis-L formula

Whang

Yoo

Kim

et al. 2020

Sci Rep

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The purpose of this study is to investigate the relationships between corneal asphericity and Haigis-L formula prediction errors in routine cataract surgery after refractive surgery for myopic correction. This retrospective study included 102 patients (102 eyes) with a history of previous PRK or LASIK and cataract surgery. Axial length, anterior chamber depth, and central corneal power were measured using the optical biometer. On the anterior corneal surface, Q-value, spherical aberration, and ecentricity at 6.0 and 8.0 mm were measured using a rotating Scheimpflug camera. The postoperative refractive outcome at 6 months, mean error, and mean absolute error were determined. Correlation tests were performed to determine the associations between pre-cataract surgery data and the prediction error. The Q-values for 6.0 and 8.0 mm corneal diameter were 1.57 ± 0.70 (range: 0.03~3.44), and 0.82 ± 0.5 (range: −0.10~−2.66). The spherical aberration for 6.0 and 8.0 mm diameter was 1.16 ± 0.39 µm (range: 0.24~2.08 µm), and 3.69 ± 0.87 µm (range: 0.91~5.91 µm). eccentricity for 6.0 and 8.0 mm diameter was − 1.22 ± 0.31 (range: −1.85 to −0.17), and −0.82 ± 0.39 (range: −1.63 to 0.32). The spherical aberration for 8.0 mm cornea diameter showed the highest correlations with the predicion error (r = 0.750; p < 0.001). When the modified Haigis-L formula considering spherical aberration for 8.0 mm produced smaller values in standard deviation of mean error (0.45D versus 0.68D), mean absolute error (0.35D versus 0.55D), and median absolute error (0.31D versus 0.51D) than the Haigis formula. Corneal asphericity influences the predictive accuracy of the Haigis-L formula. The accuracy was enhanced by taking into consideration the corneal spherical aberration for the 8.0 mm zone at precataract surgery state. open Scientific RepoRtS | (2020) 10:6445 | https://doi.

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Effect of corneal aberrations on intraocular lens power calculations

Abstract: Mrs. Canovas and Dr. Artal hold a provisional patent application on the ray-tracing procedure. Mrs. Canovas is an employee of Abbott Medical Optics Groningen B.V. No other author has a financial or proprietary interest in any material or method mentioned.

Cited by 28 publications

References 31 publications

Accuracy of intraocular lens power calculation using Scheimpflug tomography and OKULIX ray tracing software in corneal scarring

Accuracy of intraocular lens power calculation using Scheimpflug tomography and OKULIX ray tracing software in corneal scarring

Accuracy of intraocular lens power calculation using Scheimpflug tomography and OKULIX ray tracing software in corneal scarring

Influence of corneal spherical aberration on prediction error of the Haigis-L formula

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