J Korean Ophthalmol Soc.  2016 Mar;57(3):369-379. 10.3341/jkos.2016.57.3.369.

Intraocular Lens Power Calculations Using Dual Scheimpflug Analyzer

• Lee YB
• Yi KY
• Bae SH
• Kim HK
• Hyon JY
• Wee WR
• Shin YJ

• KMID: 2213237
• DOI: http://doi.org/10.3341/jkos.2016.57.3.369

Abstract

PURPOSE
To investigate the accuracy of intraocular lens power calculations using simulated keratometry (simK) of dual Scheimpflug analyzer and 5 types of formulas in cataract patients.
METHODS
The keratometry (K), axial length (AXL) and anterior chamber depth (ACD) were measured using ultrasound biometry (USB) combined with auto-keratometry (Auto-K), parital coherence interferometry (PCI; IOL master®) and dual Scheimpflug analyzer (DSA; Galilei®) in 39 eyes of 39 patients. Predicted refraction was calculated using Auto-K, mean K of PCI, and simK and total corneal power (TCP) of DSA in the Sanders-Retzlaff-Kraff (SRK-T) formula. The SRK-II, SRK-T, Holladay II, Haigis, and Hoffer-Q formula were used to calculate predicted refraction with the simK of DSA and AXL of USB. Manifest refraction, mean numerical error (MNE) and mean absolute error were evaluated 1, 3 and 6 months after cataract surgery.
RESULTS
TCP of DSA was lower compared with other keratometric values (p < 0.05). The MNE was not different among Auto-K, mean K and simK. The MNE using TCP was larger compared with Auto-K, mean K and simK at 1 month after surgery (p < 0.05). There was a difference in MNE between simK and TCP of DSA at 6 months after surgery (p < 0.05). The MNE of SRK-T formula was the smallest in the intraocular lens (IOL) power calculation using the simK of DSA.
CONCLUSIONS
We suggest using IOL power calculations with simK of DSA and SRK-T formula rather than TCP of DSA in cataract patients with normal corneas.

Keyword

Cataract surgery; Dual Scheimpflug analyger; Intraocular lens power calculation

MeSH Terms

Anterior Chamber
Biometry
Cataract
Cornea
Humans
Interferometry
Lenses, Intraocular*
Ultrasonography

Figure

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  Figure 1. Mean K according to biometry. (A) TCP is low er com pared to auto-keratometry (Auto-K), PCI and simK (p < 0.001 for all, paired t-test). (B) TCP is correlated with PCI (r = 0.653, p < 0.001, Pearson correlation analysis). K = keratometry; PCI = partial coherence interferometry; simK = simulated keratometry; TCP = total corneal power. *Statistically significant.

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  Figure 2. Correlation between AXL measured by USB and PCI and Bland-Altman plot of axial length between USB and PCI. (A) Axial length measured by USB was well correlated with PCI (r = 0.965, p < 0.001, Pearson correlation analysis). (B) 95% limits of agreement for axial length difference (USB-PCI) is −0.45 to 0.37. PCI = partial coherence interferometry; AXL = axial lengths; USB = ultrasound biometry; SD = standard deviation.

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  Figure 3. Correlation and Bland-Altman plot of ACD between USB and PCI or DSA. (A) ACD measured by PCI was well correlated with USB (r = 0.811, p < 0.001, Pearson correlation analysis). (B) ACD measured by DSA was well correlated with USB (r = 0.982, p < 0.001, Pearson correlation analysis). (C) 95% limits of agreement for ACD difference (USB-PCI) was −0.57 to 0.59. (D) 95% limits of agreement for ACD difference (USB-DSA) was −0.18 to 0.16. ACD = anterior chamber depth; USB = ultrasound biometry; PCI = partial coherence interferometry; DSA = dual Scheimpflug analyzer; SD = standard deviation.

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  Figure 4. Predicted refraction according to biometry or formula. (A) Predicted refraction is not different between PCI and Auto-K combined with USB or between PCI and DSA. Predicted refraction is different between USB and DSA (p=0.045, paired t-test). Predicted refraction calculated using TCP is higher compared with other methods (p = 0.003 for all, paired t-test). (B) Predicted refraction is different between formulas (p < 0.05, paired t-test). PCI = partial coherence interferometry; Auto-K = auto-keratometry; USB = ultrasound biometry; DSA = dual Scheimpflug analyzer; simK = simulated keratometry; TCP = total corneal power; SRK = Sanders-Retzlaff-Kraff. *Statistically significant.

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  Figure 5. Change in MRSE overtime. There is no significant change over time (Wilcoxon rank test). MRSE = manifest refraction spherical equivalent.

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  Figure 6. MNE according to biometry overtime. MNE is not different between PCI, Auto-K combined with USB and DSA 1 month and 3 months after surgery. However, MNE calculated with DSA-simK is lower compared to USB (p = 0.046, Wilcoxon rank test). MNE using TCP is higher compared to other methods 1 month after surgery (p = 0.023, 0.013 and 0.009), and higher compared to DSA-simK 3 months and 6 months after surgery (p = 0.042 and 0.039). MNE = mean numerical error; PCI = partial coherence interferometry; Auto-K = auto-keratometry; USB = ultrasound biometry; DSA = dual Scheimpflug analyzer; simK = simulated keratometry; TCP = total corneal power. *Statistically significant.

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  Figure 7. MNE according to formula overtime. MNE by SRK-T is lower compared with SRK-2, Holladay or Hoffer-Q formula 1 month after surgery (p = 0.006, < 0.001, and 0.001, respectively, Wilcoxon rank test). MNE by Haigis formula was lower compared with SRK-2, Holladay or Hoffer-Q form ula 1 month after surgery (p < 0.001 for all). SRK-2 and Haigis are lower compared with Holladay formula 1 month after surgery (p < 0.001 for both, respectively). MNE by SRK-T is lower compared with SRK-2, Holladay or Hoffer-Q formula 6 month after surgery (p = 0.014, 0.001, and 0.018, respectively). MNE by Haigis formula is lower compared with SRK-2, Holladay or Hoffer-Q formula 6 month after surgery (p = 0.012, < 0.001 and 0.001, respectively). SRK-2 and Haigis are lower compared with Holladay formula (p < 0.001 and 0.003, respectively). MNE = mean numerical error; SRK-T = Sanders-Retzlaff-Kraff theoretical formula.

Reference

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