Exploring the optimum step size for defocus curves

James S. Wolffsohn, Amit N. Jinabhai, Alec Kingsnorth, Amy L. Sheppard, Shehzad A. Naroo, Sunil Shah, Phillip Buckhurst, Lee A. Hall, Graeme Young

Research output: Contribution to journalArticle

Abstract

Purpose: To evaluate the effect of reducing the number of visual acuity measurements made in a defocus curve on the quality of data quantified. Setting: Midland Eye, Solihull, United Kingdom. Design: Evaluation of a technique. Methods: Defocus curves were constructed by measuring visual acuity on a distance logMAR letter chart, randomizing the test letters between lens presentations. The lens powers evaluated ranged between +1.50 diopters (D) and -5.00 D in 0.50 D steps, which were also presented in a randomized order. Defocus curves were measured binocularly with the Tecnis diffractive, Rezoom refractive, Lentis rotationally asymmetric segmented (+3.00 D addition [add]), and Finevision trifocal multifocal intraocular lenses (IOLs) implanted bilaterally, and also for the diffractive IOL and refractive or rotationally asymmetric segmented (+3.00 D and +1.50 D adds) multifocal IOLs implanted contralaterally. Relative and absolute range of clear-focus metrics and area metrics were calculated for curves fitted using 0.50 D, 1.00 D, and 1.50 D steps and a near add-specific profile (ie, distance, half the near add, and the full near-add powers). Results: A significant difference in simulated results was found in at least 1 of the relative or absolute range of clear-focus or area metrics for each of the multifocal designs examined when the defocus-curve step size was increased (P<.05). Conclusion: Faster methods of capturing defocus curves from multifocal IOL designs appear to distort the metric results and are therefore not valid. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. © 2013 ASCRS and ESCRS.

Original languageEnglish
Pages (from-to)873-880
Number of pages8
JournalJournal of Cataract and Refractive Surgery
Volume39
Issue number6
Early online date18 May 2013
DOIs
Publication statusPublished - Jun 2013

Fingerprint

Intraocular Lenses
Lenses
Visual Acuity
Disclosure

Bibliographical note

Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Cite this

Wolffsohn, James S. ; Jinabhai, Amit N. ; Kingsnorth, Alec ; Sheppard, Amy L. ; Naroo, Shehzad A. ; Shah, Sunil ; Buckhurst, Phillip ; Hall, Lee A. ; Young, Graeme. / Exploring the optimum step size for defocus curves. In: Journal of Cataract and Refractive Surgery. 2013 ; Vol. 39, No. 6. pp. 873-880.
@article{9f220ec6faad42b89a9fbe42e776a14c,
title = "Exploring the optimum step size for defocus curves",
abstract = "Purpose: To evaluate the effect of reducing the number of visual acuity measurements made in a defocus curve on the quality of data quantified. Setting: Midland Eye, Solihull, United Kingdom. Design: Evaluation of a technique. Methods: Defocus curves were constructed by measuring visual acuity on a distance logMAR letter chart, randomizing the test letters between lens presentations. The lens powers evaluated ranged between +1.50 diopters (D) and -5.00 D in 0.50 D steps, which were also presented in a randomized order. Defocus curves were measured binocularly with the Tecnis diffractive, Rezoom refractive, Lentis rotationally asymmetric segmented (+3.00 D addition [add]), and Finevision trifocal multifocal intraocular lenses (IOLs) implanted bilaterally, and also for the diffractive IOL and refractive or rotationally asymmetric segmented (+3.00 D and +1.50 D adds) multifocal IOLs implanted contralaterally. Relative and absolute range of clear-focus metrics and area metrics were calculated for curves fitted using 0.50 D, 1.00 D, and 1.50 D steps and a near add-specific profile (ie, distance, half the near add, and the full near-add powers). Results: A significant difference in simulated results was found in at least 1 of the relative or absolute range of clear-focus or area metrics for each of the multifocal designs examined when the defocus-curve step size was increased (P<.05). Conclusion: Faster methods of capturing defocus curves from multifocal IOL designs appear to distort the metric results and are therefore not valid. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. {\circledC} 2013 ASCRS and ESCRS.",
author = "Wolffsohn, {James S.} and Jinabhai, {Amit N.} and Alec Kingsnorth and Sheppard, {Amy L.} and Naroo, {Shehzad A.} and Sunil Shah and Phillip Buckhurst and Hall, {Lee A.} and Graeme Young",
note = "Copyright {\circledC} 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.",
year = "2013",
month = "6",
doi = "10.1016/j.jcrs.2013.01.031",
language = "English",
volume = "39",
pages = "873--880",
journal = "Journal of Cataract and Refractive Surgery",
issn = "0886-3350",
publisher = "Elsevier",
number = "6",

}

Exploring the optimum step size for defocus curves. / Wolffsohn, James S.; Jinabhai, Amit N.; Kingsnorth, Alec; Sheppard, Amy L.; Naroo, Shehzad A.; Shah, Sunil; Buckhurst, Phillip; Hall, Lee A.; Young, Graeme.

In: Journal of Cataract and Refractive Surgery, Vol. 39, No. 6, 06.2013, p. 873-880.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Exploring the optimum step size for defocus curves

AU - Wolffsohn, James S.

AU - Jinabhai, Amit N.

AU - Kingsnorth, Alec

AU - Sheppard, Amy L.

AU - Naroo, Shehzad A.

AU - Shah, Sunil

AU - Buckhurst, Phillip

AU - Hall, Lee A.

AU - Young, Graeme

N1 - Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

PY - 2013/6

Y1 - 2013/6

N2 - Purpose: To evaluate the effect of reducing the number of visual acuity measurements made in a defocus curve on the quality of data quantified. Setting: Midland Eye, Solihull, United Kingdom. Design: Evaluation of a technique. Methods: Defocus curves were constructed by measuring visual acuity on a distance logMAR letter chart, randomizing the test letters between lens presentations. The lens powers evaluated ranged between +1.50 diopters (D) and -5.00 D in 0.50 D steps, which were also presented in a randomized order. Defocus curves were measured binocularly with the Tecnis diffractive, Rezoom refractive, Lentis rotationally asymmetric segmented (+3.00 D addition [add]), and Finevision trifocal multifocal intraocular lenses (IOLs) implanted bilaterally, and also for the diffractive IOL and refractive or rotationally asymmetric segmented (+3.00 D and +1.50 D adds) multifocal IOLs implanted contralaterally. Relative and absolute range of clear-focus metrics and area metrics were calculated for curves fitted using 0.50 D, 1.00 D, and 1.50 D steps and a near add-specific profile (ie, distance, half the near add, and the full near-add powers). Results: A significant difference in simulated results was found in at least 1 of the relative or absolute range of clear-focus or area metrics for each of the multifocal designs examined when the defocus-curve step size was increased (P<.05). Conclusion: Faster methods of capturing defocus curves from multifocal IOL designs appear to distort the metric results and are therefore not valid. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. © 2013 ASCRS and ESCRS.

AB - Purpose: To evaluate the effect of reducing the number of visual acuity measurements made in a defocus curve on the quality of data quantified. Setting: Midland Eye, Solihull, United Kingdom. Design: Evaluation of a technique. Methods: Defocus curves were constructed by measuring visual acuity on a distance logMAR letter chart, randomizing the test letters between lens presentations. The lens powers evaluated ranged between +1.50 diopters (D) and -5.00 D in 0.50 D steps, which were also presented in a randomized order. Defocus curves were measured binocularly with the Tecnis diffractive, Rezoom refractive, Lentis rotationally asymmetric segmented (+3.00 D addition [add]), and Finevision trifocal multifocal intraocular lenses (IOLs) implanted bilaterally, and also for the diffractive IOL and refractive or rotationally asymmetric segmented (+3.00 D and +1.50 D adds) multifocal IOLs implanted contralaterally. Relative and absolute range of clear-focus metrics and area metrics were calculated for curves fitted using 0.50 D, 1.00 D, and 1.50 D steps and a near add-specific profile (ie, distance, half the near add, and the full near-add powers). Results: A significant difference in simulated results was found in at least 1 of the relative or absolute range of clear-focus or area metrics for each of the multifocal designs examined when the defocus-curve step size was increased (P<.05). Conclusion: Faster methods of capturing defocus curves from multifocal IOL designs appear to distort the metric results and are therefore not valid. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. © 2013 ASCRS and ESCRS.

UR - http://www.scopus.com/inward/record.url?scp=84877995992&partnerID=8YFLogxK

U2 - 10.1016/j.jcrs.2013.01.031

DO - 10.1016/j.jcrs.2013.01.031

M3 - Article

VL - 39

SP - 873

EP - 880

JO - Journal of Cataract and Refractive Surgery

JF - Journal of Cataract and Refractive Surgery

SN - 0886-3350

IS - 6

ER -