Clinical Evaluation of the Intraoperative Refraction Technique for Intraocular Lens Power Calculation

Wong, Albert Chak Ming; Mak, Shiu Ting; Tse, Raymond Kwok Kay

doi:10.1016/j.ophtha.2009.09.004

Cited by 17 publications

(14 citation statements)

References 20 publications

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“…It also shows how accurately astigmatic measurements by IWA predicted the result at 3 months postoperatively. Furthermore, mean and median prediction errors and within target ratios for the three published aphakia formulae by Ianchulev,7 Leccisotti8 and Wong9 (computed with our dataset) as compared with our newly derived aberrometry-based formulae and with conventional biometry with the Haigis formula10 are described. The distribution of the prediction errors is illustrated in figure 4.…”

Section: Resultsmentioning

confidence: 99%

“…Refractive outcome is reported in terms of the difference between the 3-month postoperative manifest SE and the planned refractive outcome (prediction error). Once adjustments for differing back vertex distances and A-constants had been made, the data of this study were inserted into the published aphakia formulae by Ianchulev,7 Leccisotti8 and Wong9 and the corresponding calculations were computed.…”

Section: Methodsmentioning

confidence: 99%

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Intraoperative aberrometry-based aphakia refraction in patients with cataract: status and options

et al. 2016

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AimTo explore the application of intraoperative wavefront aberrometry (IWA) for aphakia-based biometry using three existing formulae derived from autorefractive retinoscopy and introducing new improved formulae. Methods In 74 patients undergoing cataract surgery, three repeated measurements of aphakic spherical equivalent (SE) were taken. All measurements were objectively graded for their quality and evaluated with the 'limits of agreement' approach. ORs were calculated and analysis of variance was applied. The intraocular lens (IOL) power that would have given the target refraction was back-calculated from manifest refraction at 3 months postoperatively. Regression analysis was performed to generate two aphakic SE-based formulae for predicting this IOL. The accuracy of the formulae was determined by comparing them to conventional biometry and published aphakia formulae. Results In 32 eyes, three consecutive aphakic measurements were successful. Objective parameters of IWA map quality significantly impacted measurement variability ( p<0.05). The limits of agreement of repeated aphakic SE readings were +0.66 dioptre (D) and −0.69 D. Intraoperative biometry by our formula resulted in 25% and 53% of all cases ±0.50D and ±1.00 D within SE target, respectively. A second formula that took axial length (AL) into account resulted in improved ratios of 41% and 70%, respectively. Conclusions A reliable application of IWA to calculate IOL power during routine cataract surgery may not be feasible given the high rate of measurement failures and the large variations of the readings. To enable reliable IOL calculation from IWA, measurement precision must be improved and aphakic IOL formulae need to be finetuned.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Intraoperative aberrometry-based aphakia refraction in patients with cataract: status and options

et al. 2016

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“…21 Concerning intraoperative measurements, two different technologies were used for IOL power calculation recently: intraoperatively performed autorefraction showed to implicate several problems, such as alignment problems, because the patients couldn't see the fixation target and the use of OVDs made measurements impossible. 22 The second more recently introduced technology is intraoperatively measured wavefront aberrometry. However, this technology was found to be inaccurate for this purpose due to several problems, such as residual viscoelastics in the anterior chamber and tear film problems.…”

Section: Discussionmentioning

confidence: 99%

Predicting the Postoperative Intraocular Lens Position Using Continuous Intraoperative Optical Coherence Tomography Measurements

Hirnschall

Amir-Asgari

Maedel

et al. 2013

Invest. Ophthalmol. Vis. Sci.

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“…Numerous devices and formulas are currently available, allowing accurate determination of the IOL power needed to reach the target refraction. [1–3,4**,5*,6–9,10*,11–16, 17*–18] In order to accomplish target refraction, axial length (AL), anterior chamber depth (ACD), and corneal radii (K1and K2) need to be accurately measured. Moreover, proper choices of IOL power calculation formulas are important, as are the use of accurate IOL constants, depending on the type of IOL and post-operative IOL location.…”

Section: Introductionmentioning

confidence: 99%

Clinically relevant biometry

Şahin

Hamrah

2012

Current Opinion in Ophthalmology

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Purpose of review Obtaining precise post-operative target refraction is of utmost importance in today’s modern cataract and refractive surgery. Given the growing number of patients undergoing premium intraocular lens implantations, patient expectation continues to rise. In order to meet heightened patient expectations, it is crucial to pay utmost attention to patient selection, accurate keratometry and biometry readings, as well as to the application of correct intraocular lens power formula with optimized lens constants. This article reviews recent advances in the field of clinical biometry and intraocular lens power calculations. Recent findings Recently developed low-coherence reflectometry optical biometry is comparable to older ultrasonic biometric and keratometric techniques. In addition, the new IOL Master software upgrade has improved reproducibility and enhanced signal acquisition. Further, the modern lens power formulas currently determine the effective lens position and the shape of the intraocular lens power prediction curve more accurately. Summary In order to reach target refraction, precise biometric measurements are imperative. Understanding the strengths and limitations of the currently available biometry devices, allows prevention of high variability and inaccuracy, ultimately determining the refractive outcomes.

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Clinical Evaluation of the Intraoperative Refraction Technique for Intraocular Lens Power Calculation

Cited by 17 publications

References 20 publications

Intraoperative aberrometry-based aphakia refraction in patients with cataract: status and options

Intraoperative aberrometry-based aphakia refraction in patients with cataract: status and options

Predicting the Postoperative Intraocular Lens Position Using Continuous Intraoperative Optical Coherence Tomography Measurements

Clinically relevant biometry

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