Intraocular lens prediction accuracy after corneal refractive surgery using K values from 3 devices

Kim, Eun Chul; Cho, Kyongjin; Hwang, Ho Sik; Hwang, Kyu Yeon; Kim, Man Soo

doi:10.1016/j.jcrs.2013.04.045

Cited by 16 publications

(13 citation statements)

References 23 publications

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“…Unlike previous studies that predominantly calculated IOL formulae using single corneal power (TNP) measured with the Pentacam system, we evaluated various different corneal K readings such as TCRP, TNP, and TRP, and included several zones (3, 4, 5 mm) [242526]. Furthermore, we used the Haigis formula to overcome the limitations of third-generation formulae.…”

Section: Discussionmentioning

confidence: 99%

Comparison of Intraocular Lens Power Calculation Methods Following Myopic Laser Refractive Surgery: New Options Using a Rotating Scheimpflug Camera

Cho

Lim

Yang

et al. 2018

Korean J Ophthalmol

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PurposeTo evaluate and compare published methods of calculating intraocular lens (IOL) power following myopic laser refractive surgery.MethodsWe performed a retrospective review of the medical records of 69 patients (69 eyes) who had undergone myopic laser refractive surgery previously and subsequently underwent cataract surgery at Samsung Medical Center in Seoul, South Korea from January 2010 to June 2016. None of the patients had pre-refractive surgery biometric data available. The Haigis-L, Shammas, Barrett True-K (no history), Wang-Koch-Maloney, Scheimpflug total corneal refractive power (TCRP) 3 and 4 mm (SRK-T and Haigis), Scheimpflug true net power, and Scheimpflug true refractive power (TRP) 3 mm, 4 mm, and 5 mm (SRK-T and Haigis) methods were employed. IOL power required for target refraction was back-calculated using stable post-cataract surgery manifest refraction, and implanted IOL power and formula accuracy were subsequently compared among calculation methods.ResultsHaigis-L, Shammas, Barrett True-K (no history), Wang-Koch-Maloney, Scheimpflug TCRP 4 mm (Haigis), Scheimpflug true net power 4 mm (Haigis), and Scheimpflug TRP 4 mm (Haigis) formulae showed high predictability, with mean arithmetic prediction errors and standard deviations of −0.25 ± 0.59, −0.05 ± 1.19, 0.00 ± 0.88, −0.26 ± 1.17, 0.00 ± 1.09, −0.71 ± 1.20, and 0.03 ± 1.25 diopters, respectively.ConclusionsVisual outcomes within 1.0 diopter of target refraction were achieved in 85% of eyes using the calculation methods listed above. Haigis-L, Barrett True-K (no history), and Scheimpflug TCRP 4 mm (Haigis) and TRP 4 mm (Haigis) methods showed comparably low prediction errors, despite the absence of historical patient information.

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Section: Discussionmentioning

confidence: 99%

Comparison of Intraocular Lens Power Calculation Methods Following Myopic Laser Refractive Surgery: New Options Using a Rotating Scheimpflug Camera

Cho

Lim

Yang

et al. 2018

Korean J Ophthalmol

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“…A few studies have shown that without preoperative records, corneal power estimated with the Pentacam HR's TNP calculation can be used for calculating IOL power; however, this approach must be used with caution, as wide limits of agreement have been reported …”

Section: Discussionmentioning

confidence: 99%

Assessing the corneal power change after refractive surgery using Scheimpflug imaging

Gyldenkerne

Ivarsen

Hjortdal

2015

Ophthalmic Physiologic Optic

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“…More advanced techniques that allow one to measure the curvature of both anterior and posterior corneal surfaces, such as optical coherence tomography and other corneal tomography systems including slit-scanning tomography, rotating slit Scheimpflug-camera, and dual- Scheimpflug, are supposed to be methods that best estimate the true corneal power and can be used as an alternative to the CHM. There have been several promising reports of measuring keratometric values using the Orbscan IIz and Pentacam systems to calculate IOL power [ 13 , 20 – 21 , 27 ]. Although both instruments can directly evaluate the posterior corneal curvature, they use different operating principles.…”

Section: Discussionmentioning

confidence: 99%

“…This could probably lead to underestimation of the IOL power and a consecutive postoperative hyperopia. Recently, other Pentacam values, such as true net power (TNP) and total corneal refractive power (TCRP), showed better performance in assessing postoperative corneal power after corneal refractive surgery in patients without a clinical history [ 21 – 22 , 27 , 30 – 31 ]. The TCRP also seemed to accurately reflect the surgically induced refractive change after myopic excimer laser surgery [ 31 ].…”

Section: Discussionmentioning

confidence: 99%

“…The “Tools” menu and then “Analyze area-Statistics” for 3.0 and 4.0 mm of the central cornea were used to obtain corneal power values at both diameters. Although the refractive change after myopic LASIK has been shown to be best estimated using the 4.0-mm total optical power in the Orbscan II system [ 12 – 14 ], some studies found that using the smaller zones in calculation provided estimates closer to the correct postoperative corneal power [ 1 , 20 – 21 ]. Hence, the 3.0-mm total optical power was also chosen to be compared with the keratometry obtained by the CHM and Pentacam.…”

Section: Methodsmentioning

confidence: 99%

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Agreement between Clinical History Method, Orbscan IIz, and Pentacam in Estimating Corneal Power after Myopic Excimer Laser Surgery

et al. 2015

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The purpose of this study was to investigate the agreement between the clinical history method (CHM), Orbscan IIz, and Pentacam in estimating corneal power after myopic excimer laser surgery. Fifty five patients who had myopic LASIK/PRK were recruited into this study. One eye of each patient was randomly selected by a computer-generated process. At 6 months after surgery, postoperative corneal power was calculated from the CHM, Orbscan IIz total optical power at the 3.0 and 4.0 mm zones, and Pentacam equivalent keratometric readings (EKRs) at 3.0, 4.0, and 4.5 mm. Statistical analyses included multilevel models, Pearson’s correlation test, and Bland-Altman plots. The Orbscan IIz 3.0-mm and 4.0 mm total optical power, and Pentacam 3.0-mm, 4.0-mm, and 4.5-mm EKR values had strong linear positive correlations with the CHM values (r = 0.90–0.94, P = <0.001, for all comparisons, Pearson’s correlation). However, only Pentacam 3.0-mm EKR was not statistically different from CHM (P = 0.17, multilevel models). The mean 3.0- and 4.0-mm total optical powers of the Orbscan IIz were significantly flatter than the values derived from CHM, while the average EKRs of the Pentacam at 4.0 and 4.5 mm were significantly steeper. The mean Orbscan IIz 3.0-mm total optical power was the lowest keratometric reading compared to the other 5 values. Large 95% LoA was observed between each of these values, particularly EKRs, and those obtained with the CHM. The width of the 95% LoA was narrowest for Orbscan IIz 3.0-mm total optical power. In conclusion, the keratometric values extracted from these 3 methods were disparate, either because of a statistically significant difference in the mean values or moderate agreement between them. Therefore, they are not considered equivalent and cannot be used interchangeably.

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Intraocular lens prediction accuracy after corneal refractive surgery using K values from 3 devices

Cited by 16 publications

References 23 publications

Comparison of Intraocular Lens Power Calculation Methods Following Myopic Laser Refractive Surgery: New Options Using a Rotating Scheimpflug Camera

Comparison of Intraocular Lens Power Calculation Methods Following Myopic Laser Refractive Surgery: New Options Using a Rotating Scheimpflug Camera

Assessing the corneal power change after refractive surgery using Scheimpflug imaging

Agreement between Clinical History Method, Orbscan IIz, and Pentacam in Estimating Corneal Power after Myopic Excimer Laser Surgery

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