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Accuracy of Corneal Power Measurements for Intraocular Lens Power Calculation after Myopic Laser In situ Keratomileusis.

Helaly HA, El-Hifnawy MA, Shaheen MS, Abou El-Kheir AF - Middle East Afr J Ophthalmol (2016 Jan-Mar)

Bottom Line: The best combination of formulas was "Shammas-PL + Double-K SRK/T formula using EKR 4 mm." Scheimflug tomography imaging using the Holladay EKR 4 mm improved the accuracy of IOL power calculation in post-LASIK eyes.The best option is a combination of formulas.We recommended the use the combined "Shammas-PL ± Double-K SRK/T formula using EKR 4 mm"h for optical outcomes.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Faculty of Medicine, Alexandria University, Alexandria, Egypt.

ABSTRACT

Purpose: To evaluate the accuracy of corneal power measurements for intraocular lens (IOL) power calculation after myopic laser in situ keratomileusis (LASIK).

Methods: The study evaluated 45 eyes with a history of myopic LASIK. Corneal power was measured using manual keratometry, automated keratometry, optical biometry, and Scheimflug tomography. Different hypothetical IOL power calculation formulas were performed for each case.

Results: The steepest mean K value was measured with manual keratometry (37.48 ± 2.86 D) followed by automated keratometry (37.31 ± 2.83 D) then optical biometry (37.06 ± 2.98 D) followed by Scheimflug tomography (36.55 ± 3.08). None of the K values generated by Scheimflug tomography were steeper than the measurements from the other 3 instruments. Using equivalent K reading (EKR) 4 mm with the Double-K SRK/T formula, the refractive outcome generated 97.8% of cases within ± 2 D, 80.0% of cases within ± 1 D, and 42.2% of cases within ± 0.5 D. The best combination of formulas was "Shammas-PL + Double-K SRK/T formula using EKR 4 mm."

Conclusion: Scheimflug tomography imaging using the Holladay EKR 4 mm improved the accuracy of IOL power calculation in post-LASIK eyes. The best option is a combination of formulas. We recommended the use the combined "Shammas-PL ± Double-K SRK/T formula using EKR 4 mm"h for optical outcomes.

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Related in: MedlinePlus

Correlation between the intraocular lens prediction error of the SRK/T formula using IOLMaster keratometry values and axial length
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Related In: Results  -  Collection

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Figure 1: Correlation between the intraocular lens prediction error of the SRK/T formula using IOLMaster keratometry values and axial length

Mentions: Linear regression analysis was used to deduce the following regression formula [Figure 1 and Table 2] to calculate IOL power using the SRK/T formula and IOLMaster K readings:


Accuracy of Corneal Power Measurements for Intraocular Lens Power Calculation after Myopic Laser In situ Keratomileusis.

Helaly HA, El-Hifnawy MA, Shaheen MS, Abou El-Kheir AF - Middle East Afr J Ophthalmol (2016 Jan-Mar)

Correlation between the intraocular lens prediction error of the SRK/T formula using IOLMaster keratometry values and axial length
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4759889&req=5

Figure 1: Correlation between the intraocular lens prediction error of the SRK/T formula using IOLMaster keratometry values and axial length
Mentions: Linear regression analysis was used to deduce the following regression formula [Figure 1 and Table 2] to calculate IOL power using the SRK/T formula and IOLMaster K readings:

Bottom Line: The best combination of formulas was "Shammas-PL + Double-K SRK/T formula using EKR 4 mm." Scheimflug tomography imaging using the Holladay EKR 4 mm improved the accuracy of IOL power calculation in post-LASIK eyes.The best option is a combination of formulas.We recommended the use the combined "Shammas-PL ± Double-K SRK/T formula using EKR 4 mm"h for optical outcomes.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Faculty of Medicine, Alexandria University, Alexandria, Egypt.

ABSTRACT

Purpose: To evaluate the accuracy of corneal power measurements for intraocular lens (IOL) power calculation after myopic laser in situ keratomileusis (LASIK).

Methods: The study evaluated 45 eyes with a history of myopic LASIK. Corneal power was measured using manual keratometry, automated keratometry, optical biometry, and Scheimflug tomography. Different hypothetical IOL power calculation formulas were performed for each case.

Results: The steepest mean K value was measured with manual keratometry (37.48 ± 2.86 D) followed by automated keratometry (37.31 ± 2.83 D) then optical biometry (37.06 ± 2.98 D) followed by Scheimflug tomography (36.55 ± 3.08). None of the K values generated by Scheimflug tomography were steeper than the measurements from the other 3 instruments. Using equivalent K reading (EKR) 4 mm with the Double-K SRK/T formula, the refractive outcome generated 97.8% of cases within ± 2 D, 80.0% of cases within ± 1 D, and 42.2% of cases within ± 0.5 D. The best combination of formulas was "Shammas-PL + Double-K SRK/T formula using EKR 4 mm."

Conclusion: Scheimflug tomography imaging using the Holladay EKR 4 mm improved the accuracy of IOL power calculation in post-LASIK eyes. The best option is a combination of formulas. We recommended the use the combined "Shammas-PL ± Double-K SRK/T formula using EKR 4 mm"h for optical outcomes.

Show MeSH
Related in: MedlinePlus