Accuracy of Scheimpflug corneal power measurements for intraocular lens power calculation

Giacomo Savini, Piero Barboni, Michele Carbonelli, Kenneth J. Hoffer

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

Purpose: To evaluate the accuracy of corneal power measurements by the Pentacam Scheimpflug system for intraocular lens (IOL) power calculation. Setting: Studio Oculistico d'Azeglio, Bologna, Italy. Methods: Consecutive patients having phacoemulsification and in-the-bag IOL implantation were prospectively studied. Intraocular lens power was calculated by entering 3 combinations of data into the Hoffer Q formula: (1) corneal power measurements by corneal topography (simulated keratometry) and axial length (AL) measurements by Ultrascan ultrasound (US) immersion biometry; (2) Scheimpflug corneal power measurements (simulated keratometry) and US AL measurements; (3) corneal power and AL measurements by partial coherence interferometry (PCI) (IOLMaster). The prediction error was calculated as the difference between the predicted and the measured refraction 1 month postoperatively. Results: Forty-one eyes were evaluated. The mean arithmetic error was zero for all combinations of measurements due to constant optimization. The mean absolute error (MAE) of the Scheimpflug-US combination was good (0.44 diopters [D] ± 0.30 [SD]) but significantly higher than the topography-US combination and PCI (0.33 ± 0.29 D and 0.33 ± 0.23 D, respectively) (P = .043). The percentage of eyes with an MAE of 0.75 D or greater was higher with the Scheimpflug-US combination (7 eyes, 17%) than with the corneal topography-US combination (2 eyes, 4.8%) or PCI (3 eyes, 7.3%). Conclusion: Corneal power measurements with the Pentacam Scheimpflug system should be used in IOL power calculation formulas with caution because the accuracy is good but is not as high as with standard measurement methods.

Original languageEnglish
Pages (from-to)1193-1197
Number of pages5
JournalJournal of Cataract and Refractive Surgery
Volume35
Issue number7
DOIs
Publication statusPublished - Jul 2009

Fingerprint

Intraocular Lenses
Interferometry
Corneal Topography
Biometry
Intraocular Lens Implantation
Phacoemulsification
Immersion
Italy

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Surgery

Cite this

Accuracy of Scheimpflug corneal power measurements for intraocular lens power calculation. / Savini, Giacomo; Barboni, Piero; Carbonelli, Michele; Hoffer, Kenneth J.

In: Journal of Cataract and Refractive Surgery, Vol. 35, No. 7, 07.2009, p. 1193-1197.

Research output: Contribution to journalArticle

Savini, Giacomo ; Barboni, Piero ; Carbonelli, Michele ; Hoffer, Kenneth J. / Accuracy of Scheimpflug corneal power measurements for intraocular lens power calculation. In: Journal of Cataract and Refractive Surgery. 2009 ; Vol. 35, No. 7. pp. 1193-1197.
@article{7b7453e5a42d4e2095eb74a96dfdb88f,
title = "Accuracy of Scheimpflug corneal power measurements for intraocular lens power calculation",
abstract = "Purpose: To evaluate the accuracy of corneal power measurements by the Pentacam Scheimpflug system for intraocular lens (IOL) power calculation. Setting: Studio Oculistico d'Azeglio, Bologna, Italy. Methods: Consecutive patients having phacoemulsification and in-the-bag IOL implantation were prospectively studied. Intraocular lens power was calculated by entering 3 combinations of data into the Hoffer Q formula: (1) corneal power measurements by corneal topography (simulated keratometry) and axial length (AL) measurements by Ultrascan ultrasound (US) immersion biometry; (2) Scheimpflug corneal power measurements (simulated keratometry) and US AL measurements; (3) corneal power and AL measurements by partial coherence interferometry (PCI) (IOLMaster). The prediction error was calculated as the difference between the predicted and the measured refraction 1 month postoperatively. Results: Forty-one eyes were evaluated. The mean arithmetic error was zero for all combinations of measurements due to constant optimization. The mean absolute error (MAE) of the Scheimpflug-US combination was good (0.44 diopters [D] ± 0.30 [SD]) but significantly higher than the topography-US combination and PCI (0.33 ± 0.29 D and 0.33 ± 0.23 D, respectively) (P = .043). The percentage of eyes with an MAE of 0.75 D or greater was higher with the Scheimpflug-US combination (7 eyes, 17{\%}) than with the corneal topography-US combination (2 eyes, 4.8{\%}) or PCI (3 eyes, 7.3{\%}). Conclusion: Corneal power measurements with the Pentacam Scheimpflug system should be used in IOL power calculation formulas with caution because the accuracy is good but is not as high as with standard measurement methods.",
author = "Giacomo Savini and Piero Barboni and Michele Carbonelli and Hoffer, {Kenneth J.}",
year = "2009",
month = "7",
doi = "10.1016/j.jcrs.2009.02.031",
language = "English",
volume = "35",
pages = "1193--1197",
journal = "Journal of Cataract and Refractive Surgery",
issn = "0886-3350",
publisher = "Elsevier Inc.",
number = "7",

}

TY - JOUR

T1 - Accuracy of Scheimpflug corneal power measurements for intraocular lens power calculation

AU - Savini, Giacomo

AU - Barboni, Piero

AU - Carbonelli, Michele

AU - Hoffer, Kenneth J.

PY - 2009/7

Y1 - 2009/7

N2 - Purpose: To evaluate the accuracy of corneal power measurements by the Pentacam Scheimpflug system for intraocular lens (IOL) power calculation. Setting: Studio Oculistico d'Azeglio, Bologna, Italy. Methods: Consecutive patients having phacoemulsification and in-the-bag IOL implantation were prospectively studied. Intraocular lens power was calculated by entering 3 combinations of data into the Hoffer Q formula: (1) corneal power measurements by corneal topography (simulated keratometry) and axial length (AL) measurements by Ultrascan ultrasound (US) immersion biometry; (2) Scheimpflug corneal power measurements (simulated keratometry) and US AL measurements; (3) corneal power and AL measurements by partial coherence interferometry (PCI) (IOLMaster). The prediction error was calculated as the difference between the predicted and the measured refraction 1 month postoperatively. Results: Forty-one eyes were evaluated. The mean arithmetic error was zero for all combinations of measurements due to constant optimization. The mean absolute error (MAE) of the Scheimpflug-US combination was good (0.44 diopters [D] ± 0.30 [SD]) but significantly higher than the topography-US combination and PCI (0.33 ± 0.29 D and 0.33 ± 0.23 D, respectively) (P = .043). The percentage of eyes with an MAE of 0.75 D or greater was higher with the Scheimpflug-US combination (7 eyes, 17%) than with the corneal topography-US combination (2 eyes, 4.8%) or PCI (3 eyes, 7.3%). Conclusion: Corneal power measurements with the Pentacam Scheimpflug system should be used in IOL power calculation formulas with caution because the accuracy is good but is not as high as with standard measurement methods.

AB - Purpose: To evaluate the accuracy of corneal power measurements by the Pentacam Scheimpflug system for intraocular lens (IOL) power calculation. Setting: Studio Oculistico d'Azeglio, Bologna, Italy. Methods: Consecutive patients having phacoemulsification and in-the-bag IOL implantation were prospectively studied. Intraocular lens power was calculated by entering 3 combinations of data into the Hoffer Q formula: (1) corneal power measurements by corneal topography (simulated keratometry) and axial length (AL) measurements by Ultrascan ultrasound (US) immersion biometry; (2) Scheimpflug corneal power measurements (simulated keratometry) and US AL measurements; (3) corneal power and AL measurements by partial coherence interferometry (PCI) (IOLMaster). The prediction error was calculated as the difference between the predicted and the measured refraction 1 month postoperatively. Results: Forty-one eyes were evaluated. The mean arithmetic error was zero for all combinations of measurements due to constant optimization. The mean absolute error (MAE) of the Scheimpflug-US combination was good (0.44 diopters [D] ± 0.30 [SD]) but significantly higher than the topography-US combination and PCI (0.33 ± 0.29 D and 0.33 ± 0.23 D, respectively) (P = .043). The percentage of eyes with an MAE of 0.75 D or greater was higher with the Scheimpflug-US combination (7 eyes, 17%) than with the corneal topography-US combination (2 eyes, 4.8%) or PCI (3 eyes, 7.3%). Conclusion: Corneal power measurements with the Pentacam Scheimpflug system should be used in IOL power calculation formulas with caution because the accuracy is good but is not as high as with standard measurement methods.

UR - http://www.scopus.com/inward/record.url?scp=67649803385&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=67649803385&partnerID=8YFLogxK

U2 - 10.1016/j.jcrs.2009.02.031

DO - 10.1016/j.jcrs.2009.02.031

M3 - Article

VL - 35

SP - 1193

EP - 1197

JO - Journal of Cataract and Refractive Surgery

JF - Journal of Cataract and Refractive Surgery

SN - 0886-3350

IS - 7

ER -