Effects on IOL Power Calculation and Expected Clinical Outcomes of Axial Length Measurements Based on Multiple vs Single Refractive Indices

H John Shammas,1,2 Maya C Shammas,2 Renu V Jivrajka,2 David L Cooke,3 Richard Potvin4 1Department of Ophthalmology, The Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA; 2Shammas Eye Medical Center, Lynwood, CA, USA; 3Great Lakes Eye Care, St. Joseph, MI 49085,...

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Autores principales: Shammas HJ, Shammas MC, Jivrajka RV, Cooke DL, Potvin R
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Publicado: Dove Medical Press 2020
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spelling oai:doaj.org-article:7ea2ced5536047d8bbdde75c44dd93112021-12-02T10:28:11ZEffects on IOL Power Calculation and Expected Clinical Outcomes of Axial Length Measurements Based on Multiple vs Single Refractive Indices1177-5483https://doaj.org/article/7ea2ced5536047d8bbdde75c44dd93112020-06-01T00:00:00Zhttps://www.dovepress.com/effects-on-iol-power-calculation-and-expected-clinical-outcomes-of-axi-peer-reviewed-article-OPTHhttps://doaj.org/toc/1177-5483H John Shammas,1,2 Maya C Shammas,2 Renu V Jivrajka,2 David L Cooke,3 Richard Potvin4 1Department of Ophthalmology, The Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA; 2Shammas Eye Medical Center, Lynwood, CA, USA; 3Great Lakes Eye Care, St. Joseph, MI 49085, USA; 4Science in Vision, Akron, NY, USACorrespondence: H John ShammasShammas Eye Medical Center, 3510 Martin Luther King Jr. Blvd., Lynwood, CA 90262, USAEmail HShammas@aol.comPurpose: To compare axial length measurements based on multiple specific refractive indices for each segment of the eye to those obtained using a single refractive index for the entire eye and to evaluate the subsequent effects on IOL power calculation.Setting: One site in Lynwood, CA.Design: Single-arm, non-interventional, non-randomized retrospective chart review.Methods: Eyes undergoing cataract surgery where biometry and IOL power calculations were based on axial length calculated with multiple specific refractive indices (multiple) were evaluated. A simulated axial length based on using a single refractive index was calculated for each case (single). The expected residual refractions based on different IOL formulas were calculated for both single and multiple groups. Formulas were then optimized, and the mean prediction errors (MPE) and mean absolute prediction errors (MAE) were calculated, based on the difference between the (optimized) expected value and the actual refractive outcome.Results: A total of 595 eligible eyes were evaluated. Differences between the axial lengths determined in the single and multiple groups ranged from +0.28 mm to − 0.14 mm, with a significant correlation between the difference in AL and average AL (r2 = 0.73, p < 0.001). AL differences between groups were statistically significant in long and short eyes (p < 0.001) but not in average eyes or overall (p > 0.25). In nearly all cases, the average MPE in the multiple group was lower than that for the single group across all axial lengths and formulas. When larger differences in MAE were present, the multiple group results were more often lower (better).Conclusion: Differences were found between axial lengths calculated using a single refractive index and multiple refractive indices, mainly in the short and long eyes. Differences had some effect on IOL power calculation. Such effects may become increasingly important as the precision of formulas increases.Keywords: IOL power calculation, biometry, axial length, sum of segments, refractive index, optical coherence tomographyShammas HJShammas MCJivrajka RVCooke DLPotvin RDove Medical Pressarticleiol power calculationbiometryaxial lengthsum of segmentsrefractive indexoptical coherence tomographyOphthalmologyRE1-994ENClinical Ophthalmology, Vol Volume 14, Pp 1511-1519 (2020)
institution DOAJ
collection DOAJ
language EN
topic iol power calculation
biometry
axial length
sum of segments
refractive index
optical coherence tomography
Ophthalmology
RE1-994
spellingShingle iol power calculation
biometry
axial length
sum of segments
refractive index
optical coherence tomography
Ophthalmology
RE1-994
Shammas HJ
Shammas MC
Jivrajka RV
Cooke DL
Potvin R
Effects on IOL Power Calculation and Expected Clinical Outcomes of Axial Length Measurements Based on Multiple vs Single Refractive Indices
description H John Shammas,1,2 Maya C Shammas,2 Renu V Jivrajka,2 David L Cooke,3 Richard Potvin4 1Department of Ophthalmology, The Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA; 2Shammas Eye Medical Center, Lynwood, CA, USA; 3Great Lakes Eye Care, St. Joseph, MI 49085, USA; 4Science in Vision, Akron, NY, USACorrespondence: H John ShammasShammas Eye Medical Center, 3510 Martin Luther King Jr. Blvd., Lynwood, CA 90262, USAEmail HShammas@aol.comPurpose: To compare axial length measurements based on multiple specific refractive indices for each segment of the eye to those obtained using a single refractive index for the entire eye and to evaluate the subsequent effects on IOL power calculation.Setting: One site in Lynwood, CA.Design: Single-arm, non-interventional, non-randomized retrospective chart review.Methods: Eyes undergoing cataract surgery where biometry and IOL power calculations were based on axial length calculated with multiple specific refractive indices (multiple) were evaluated. A simulated axial length based on using a single refractive index was calculated for each case (single). The expected residual refractions based on different IOL formulas were calculated for both single and multiple groups. Formulas were then optimized, and the mean prediction errors (MPE) and mean absolute prediction errors (MAE) were calculated, based on the difference between the (optimized) expected value and the actual refractive outcome.Results: A total of 595 eligible eyes were evaluated. Differences between the axial lengths determined in the single and multiple groups ranged from +0.28 mm to − 0.14 mm, with a significant correlation between the difference in AL and average AL (r2 = 0.73, p < 0.001). AL differences between groups were statistically significant in long and short eyes (p < 0.001) but not in average eyes or overall (p > 0.25). In nearly all cases, the average MPE in the multiple group was lower than that for the single group across all axial lengths and formulas. When larger differences in MAE were present, the multiple group results were more often lower (better).Conclusion: Differences were found between axial lengths calculated using a single refractive index and multiple refractive indices, mainly in the short and long eyes. Differences had some effect on IOL power calculation. Such effects may become increasingly important as the precision of formulas increases.Keywords: IOL power calculation, biometry, axial length, sum of segments, refractive index, optical coherence tomography
format article
author Shammas HJ
Shammas MC
Jivrajka RV
Cooke DL
Potvin R
author_facet Shammas HJ
Shammas MC
Jivrajka RV
Cooke DL
Potvin R
author_sort Shammas HJ
title Effects on IOL Power Calculation and Expected Clinical Outcomes of Axial Length Measurements Based on Multiple vs Single Refractive Indices
title_short Effects on IOL Power Calculation and Expected Clinical Outcomes of Axial Length Measurements Based on Multiple vs Single Refractive Indices
title_full Effects on IOL Power Calculation and Expected Clinical Outcomes of Axial Length Measurements Based on Multiple vs Single Refractive Indices
title_fullStr Effects on IOL Power Calculation and Expected Clinical Outcomes of Axial Length Measurements Based on Multiple vs Single Refractive Indices
title_full_unstemmed Effects on IOL Power Calculation and Expected Clinical Outcomes of Axial Length Measurements Based on Multiple vs Single Refractive Indices
title_sort effects on iol power calculation and expected clinical outcomes of axial length measurements based on multiple vs single refractive indices
publisher Dove Medical Press
publishDate 2020
url https://doaj.org/article/7ea2ced5536047d8bbdde75c44dd9311
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