Accuracy of a dual Scheimpflug analyzer and a corneal topography system for intraocular lens power calculation in unoperated eyes

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

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Purpose: To evaluate the accuracy of the corneal power measurements by a dual Scheimpflug analyzer (Galilei) and a corneal topography system (Keratron) for intraocular lens (IOL) power calculation in unoperated eyes. Setting: Private practice. Design: Case series. Methods: The IOL power was calculated for eyes having phacoemulsification and in-the-bag IOL implantation by entering into the Hoffer Q, Holladay 1, and SRK/T formulas 3 corneal power measurements: (1) simulated keratometry (K) by corneal topography, (2) simulated K derived by anterior corneal curvature only using the dual Scheimpflug analyzer, (3) total corneal power derived by anterior and posterior corneal curvatures through ray tracing using the dual Scheimpflug analyzer. The prediction error was calculated as the difference between the predicted and the measured refraction 1 month postoperatively. Results: Forty-three consecutive patients were enrolled. The mean arithmetic error was zero for all combinations of measurements due to constant optimization. Using the Hoffer Q formula, the mean absolute prediction errors were 0.23 diopters (D) ± 0.22 (SD) for the corneal topographer simulated K, 0.21 ± 0.18 D for the Scheimpflug simulated K, and 0.27 ±0.20 D for the Scheimpflug total corneal power (P>.05). No statistically significant different results (compared with the Hoffer Q formula) were obtained with the Holladay 1 and SRK/T formulas. Conclusions: Both devices provided corneal power measurements that led to accurate IOL power calculation. The total corneal power by the dual Scheimpflug system is the first corneal power measurement shown to lead to accurate IOL power calculation without using the standard keratometric index. Financial Disclosure: Drs. Savini, Barboni, and Carbonelli have no financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.

Original languageEnglish
Pages (from-to)72-76
Number of pages5
JournalJournal of Cataract and Refractive Surgery
Volume37
Issue number1
DOIs
Publication statusPublished - Jan 2011

Fingerprint

Corneal Topography
Intraocular Lenses
Disclosure
Power (Psychology)
Intraocular Lens Implantation
Phacoemulsification
Private Practice

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Surgery

Cite this

Accuracy of a dual Scheimpflug analyzer and a corneal topography system for intraocular lens power calculation in unoperated eyes. / Savini, Giacomo; Barboni, Piero; Carbonelli, Michele; Hoffer, Kenneth J.

In: Journal of Cataract and Refractive Surgery, Vol. 37, No. 1, 01.2011, p. 72-76.

Research output: Contribution to journalArticle

@article{35f9430f47104d21b8cd1c2fb8dd7103,
title = "Accuracy of a dual Scheimpflug analyzer and a corneal topography system for intraocular lens power calculation in unoperated eyes",
abstract = "Purpose: To evaluate the accuracy of the corneal power measurements by a dual Scheimpflug analyzer (Galilei) and a corneal topography system (Keratron) for intraocular lens (IOL) power calculation in unoperated eyes. Setting: Private practice. Design: Case series. Methods: The IOL power was calculated for eyes having phacoemulsification and in-the-bag IOL implantation by entering into the Hoffer Q, Holladay 1, and SRK/T formulas 3 corneal power measurements: (1) simulated keratometry (K) by corneal topography, (2) simulated K derived by anterior corneal curvature only using the dual Scheimpflug analyzer, (3) total corneal power derived by anterior and posterior corneal curvatures through ray tracing using the dual Scheimpflug analyzer. The prediction error was calculated as the difference between the predicted and the measured refraction 1 month postoperatively. Results: Forty-three consecutive patients were enrolled. The mean arithmetic error was zero for all combinations of measurements due to constant optimization. Using the Hoffer Q formula, the mean absolute prediction errors were 0.23 diopters (D) ± 0.22 (SD) for the corneal topographer simulated K, 0.21 ± 0.18 D for the Scheimpflug simulated K, and 0.27 ±0.20 D for the Scheimpflug total corneal power (P>.05). No statistically significant different results (compared with the Hoffer Q formula) were obtained with the Holladay 1 and SRK/T formulas. Conclusions: Both devices provided corneal power measurements that led to accurate IOL power calculation. The total corneal power by the dual Scheimpflug system is the first corneal power measurement shown to lead to accurate IOL power calculation without using the standard keratometric index. Financial Disclosure: Drs. Savini, Barboni, and Carbonelli have no financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.",
author = "Giacomo Savini and Piero Barboni and Michele Carbonelli and Hoffer, {Kenneth J.}",
year = "2011",
month = "1",
doi = "10.1016/j.jcrs.2010.08.036",
language = "English",
volume = "37",
pages = "72--76",
journal = "Journal of Cataract and Refractive Surgery",
issn = "0886-3350",
publisher = "Elsevier Inc.",
number = "1",

}

TY - JOUR

T1 - Accuracy of a dual Scheimpflug analyzer and a corneal topography system for intraocular lens power calculation in unoperated eyes

AU - Savini, Giacomo

AU - Barboni, Piero

AU - Carbonelli, Michele

AU - Hoffer, Kenneth J.

PY - 2011/1

Y1 - 2011/1

N2 - Purpose: To evaluate the accuracy of the corneal power measurements by a dual Scheimpflug analyzer (Galilei) and a corneal topography system (Keratron) for intraocular lens (IOL) power calculation in unoperated eyes. Setting: Private practice. Design: Case series. Methods: The IOL power was calculated for eyes having phacoemulsification and in-the-bag IOL implantation by entering into the Hoffer Q, Holladay 1, and SRK/T formulas 3 corneal power measurements: (1) simulated keratometry (K) by corneal topography, (2) simulated K derived by anterior corneal curvature only using the dual Scheimpflug analyzer, (3) total corneal power derived by anterior and posterior corneal curvatures through ray tracing using the dual Scheimpflug analyzer. The prediction error was calculated as the difference between the predicted and the measured refraction 1 month postoperatively. Results: Forty-three consecutive patients were enrolled. The mean arithmetic error was zero for all combinations of measurements due to constant optimization. Using the Hoffer Q formula, the mean absolute prediction errors were 0.23 diopters (D) ± 0.22 (SD) for the corneal topographer simulated K, 0.21 ± 0.18 D for the Scheimpflug simulated K, and 0.27 ±0.20 D for the Scheimpflug total corneal power (P>.05). No statistically significant different results (compared with the Hoffer Q formula) were obtained with the Holladay 1 and SRK/T formulas. Conclusions: Both devices provided corneal power measurements that led to accurate IOL power calculation. The total corneal power by the dual Scheimpflug system is the first corneal power measurement shown to lead to accurate IOL power calculation without using the standard keratometric index. Financial Disclosure: Drs. Savini, Barboni, and Carbonelli have no financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.

AB - Purpose: To evaluate the accuracy of the corneal power measurements by a dual Scheimpflug analyzer (Galilei) and a corneal topography system (Keratron) for intraocular lens (IOL) power calculation in unoperated eyes. Setting: Private practice. Design: Case series. Methods: The IOL power was calculated for eyes having phacoemulsification and in-the-bag IOL implantation by entering into the Hoffer Q, Holladay 1, and SRK/T formulas 3 corneal power measurements: (1) simulated keratometry (K) by corneal topography, (2) simulated K derived by anterior corneal curvature only using the dual Scheimpflug analyzer, (3) total corneal power derived by anterior and posterior corneal curvatures through ray tracing using the dual Scheimpflug analyzer. The prediction error was calculated as the difference between the predicted and the measured refraction 1 month postoperatively. Results: Forty-three consecutive patients were enrolled. The mean arithmetic error was zero for all combinations of measurements due to constant optimization. Using the Hoffer Q formula, the mean absolute prediction errors were 0.23 diopters (D) ± 0.22 (SD) for the corneal topographer simulated K, 0.21 ± 0.18 D for the Scheimpflug simulated K, and 0.27 ±0.20 D for the Scheimpflug total corneal power (P>.05). No statistically significant different results (compared with the Hoffer Q formula) were obtained with the Holladay 1 and SRK/T formulas. Conclusions: Both devices provided corneal power measurements that led to accurate IOL power calculation. The total corneal power by the dual Scheimpflug system is the first corneal power measurement shown to lead to accurate IOL power calculation without using the standard keratometric index. Financial Disclosure: Drs. Savini, Barboni, and Carbonelli have no financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.

UR - http://www.scopus.com/inward/record.url?scp=78650491634&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=78650491634&partnerID=8YFLogxK

U2 - 10.1016/j.jcrs.2010.08.036

DO - 10.1016/j.jcrs.2010.08.036

M3 - Article

VL - 37

SP - 72

EP - 76

JO - Journal of Cataract and Refractive Surgery

JF - Journal of Cataract and Refractive Surgery

SN - 0886-3350

IS - 1

ER -