Refractive Predictability and Biometry Agreement of a Combined Swept Source Optical Coherence and Reflectometry Biometer Compared to an Optical Low Coherence Reflectometry Biometer and an SS-OCT Biometer

Gjerdrum, Bjørn; Gundersen, Kjell Gunnar; Nilsen, Christian; Gundersen, Morten; Jensen, Per

doi:10.2147/opth.s408685

Cited by 4 publications

(3 citation statements)

References 28 publications

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“…With an expected standard deviation of 0.12 D between repeated measurements of average keratometry, 36 eyes in each group would be needed to reliably detect a difference of 0.08 D between groups (we utilized the resource in www.powerandsamplesize.com to calculate the sample size). 23 …”

Section: Methodsmentioning

confidence: 99%

The Significance of Dry Eye Signs on Preoperative Keratometry Measurements in Patients Scheduled for Cataract Surgery

Nilsen,

Gundersen,

Graae Jensen

et al. 2024

OPTH

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Purpose The primary objective was to investigate if subjects with dry eyes had increased variability of keratometry measurements prior to cataract surgery compared to subjects with non-dry eyes. Secondary objectives were to determine which separate signs affected keratometry. Patients and Methods This study was part of a prospective interventional randomized controlled trial. After dry eye diagnostics were performed (signs only) subjects were divided into sign of dry eye (SDE) positive and negative groups. To investigate variability, we performed two keratometry measurements for each subject with three different optical biometers: Anterion (OCT optical biometer), Eyestar (combined OCT and reflection-based optical biometer), and Lenstar (reflection based-optical biometer). Results One hundred and thirty-one subjects were available for analysis. The variability of astigmatism was significantly higher for subjects with hyperosmolarity compared to normal eyes for the Lenstar, as was the percentage of eyes with variability of astigmatism greater than 0.25 D. The percentage of eyes with variability of average K greater than 0.25 D was higher for subjects with non-invasive keratograph break-up time <10 seconds (NIKBUT positive) compared to normal eyes for the Lenstar. Conclusion Combined diagnostic criteria (signs only) showed no statistically significant differences for keratometry measurements between SDE positive and negative. Eyes with hyperosmolarity and NIKBUT positive showed statistically higher variability of keratometry measurements compared to normal eyes for Lenstar, but not for the Anterion or Eyestar biometers.

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Section: Methodsmentioning

confidence: 99%

The Significance of Dry Eye Signs on Preoperative Keratometry Measurements in Patients Scheduled for Cataract Surgery

Nilsen,

Gundersen,

Graae Jensen

et al. 2024

OPTH

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“…Low CoV were found for the AL measurements (0.03% and 0.06% for the Eyestar 900 and the Lenstar LS 900, respectively Both biometers were able to provide repeat measurements for the different parameters and can be used interchangeably. 6 Gjerdrum et al, 62 Clin Ophthalmol, 2023 May 22;17:1439–1452. To assess the agreement of refractive prediction of SSOCT with segmental AL calculation and another SSOCT with optical low coherence reflectometry (OLCR) biometer and to describe the refractive outcome, visual acuity and agreement between different biometric patterns Retrospective, 129 eyes, Biometric parameters were assessed and Barrett Universal II formula was used to calculate the IOL power for all three devices.…”

Section: Introductionmentioning

confidence: 99%

Current Concepts and Recent Updates of Optical Biometry- A Comprehensive Review

Pathak,

Sahu,

Kumar

et al. 2024

OPTH

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One of the most recent advancements in the field of cataract surgery is optical biometry. With the advent of optical biometry ocular measurements are now simpler, quicker, and more precise. The devices have made intraocular lens (IOL) power calculations easier in difficult situations too, such as in cases with extremes of axial lengths, silicone filled eyes, cataract surgery in post-keratoplasty eyes, post Laser-Assisted in Situ Keratomileusis (LASIK) eyes, etc. The gold standard for IOL power calculation in the present day is by the use of optical biometry devices. The anatomical measurements by these devices are highly precise and because of these measurements and the incorporation of various IOL power calculation formulas the optical biometry devices give the accurate power and the post-operative visual outcome is highly satisfactory among the patients. The growing use of these devices has made cataract the most commonly performed refractive surgical procedure nowadays. In the current scenario, optical biometry has widespread acceptance in almost all countries and has many advantages over ultrasound or immersion biometry. Cataract surgeons can obtain easy and reliable measurements from these devices. Refractive surprises have also decreased considerably with their use. This article will comprehensively review the principles of the various optical biometry devices, the parameters used in each of the devices, the advantages and disadvantages, and add more like what all this article will add.

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“…Lacking AL correction in GRI biometers could explain the AL differences in extreme values compared to sum-of-segments biometer, especially in long eyes, as noted by the authors in this paper. 1,3 Authors also declared that they used optimized constant for Lenstar and after they reduced the mean arithmetic (ME) refractive prediction error (RPE) to zero for each device, surgeon and IOL. We have some concerns in this regard.…”

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Axial Length Correction in Evaluation of Refractive Predictability and Biometry Agreement [Letter]

Cione¹,

Padula²,

Formicola³

2023

OPTH

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We read with great interest the article by Gjerdrum et al concerning the comparison of refractive predictability between different biometers. 1 Analysis of both group refractive index (GRI) and single refractive indices principles is fascinating. However, we would like to make a few comments regarding some points of the study that need to be clarified.Authors correctly listed some causes of postoperative refractive errors, such as inaccurate prediction of corneal power 2 and axial length (AL). We totally agree, but we ask ourselves why the authors forgot to mention the AL reliability due to lens opacity or the corneal thickness/AL ratio in their work. In fact, as the authors evaluated patients undergoing cataract surgery, lens opacity could affect GRI biometers reliability, as demonstrated by De Bernardo et al. 3 They proposed a correction factor (ALc) to improve the AL measurement reliability which can eliminate any systematic error resulting from the biometer. Since authors analyzed two biometers based on GRI, authors should have taken in consideration ALc for these instruments. Lacking AL correction in GRI biometers could explain the AL differences in extreme values compared to sum-of-segments biometer, especially in long eyes, as noted by the authors in this paper. 1,3 Authors also declared that they used optimized constant for Lenstar and after they reduced the mean arithmetic (ME) refractive prediction error (RPE) to zero for each device, surgeon and IOL. We have some concerns in this regard. Firstly, also ME obtained with Lenstar is different from zero, as reported in Table 1. In addition, authors did not report how many eyes were analyzed for each IOL model. This is crucial missing information, because to perform an acceptable optimization at least 3 cases for each IOL model should be listed. 4 Moreover, we wonder why also toric IOLs were included.This study focused on AL reliability, but different RPE obtained by Argos and Anterion were caused by keratometric readings. In fact, these biometers utilize different technologies and diameters to evaluate keratometry. Anyway, optimization of the process could mute every difference between instruments in refractive predictability. Since this process aims to eliminate the systematic error, including optical biometer, 5 we wonder if it could be considered correct to optimize formulas for each biometer in a study that aims to analyze differences between these devices.We have some concerns also regarding the statistical analysis. No data normality check and statement of statistic test used to compare percentages were presented, so, we are surprised by the analysis of subgroups consisting of only 10 or 11 patients! This is in contrast with a minimum sample size of 22 eyes calculated by the authors. For this reason, the analysis of subgroups that comprehend less than the minimum sample size can be misleading. In this scenario, it could be preferable to analyze data according to quartile ranges to have equal subgroups, as carried out by other recent studies. 2 Results...

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Refractive Predictability and Biometry Agreement of a Combined Swept Source Optical Coherence and Reflectometry Biometer Compared to an Optical Low Coherence Reflectometry Biometer and an SS-OCT Biometer

Cited by 4 publications

References 28 publications

The Significance of Dry Eye Signs on Preoperative Keratometry Measurements in Patients Scheduled for Cataract Surgery

The Significance of Dry Eye Signs on Preoperative Keratometry Measurements in Patients Scheduled for Cataract Surgery

Current Concepts and Recent Updates of Optical Biometry- A Comprehensive Review

Axial Length Correction in Evaluation of Refractive Predictability and Biometry Agreement [Letter]

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