Article Text
Abstract
Aim To 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 fine-tuned.
- Clinical Trial
- Optics and Refraction
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Footnotes
J. O. Huelle presented parts of this study to the XXXII Congress of the ESCRS, September 2014, London, UK.
Contributors Conceived the study's questions: SJL, GR, TK and JOH. Developed the manuscript: JOH, SJL, TK and VD. Coordinated manuscript development and completed first draft of the manuscript: JOH. Edited the manuscript: SJL, VD, NH and JOH. Performed part of writing or editing of the manuscript: SJL, VD and NH. Made an intellectual contribution to the manuscript: GR, TK and NEH. Calculated statistics: VD and JOH. Advised on the manuscript: SJL, TK and NH. Approved final version of the manuscript prior to submission: SJL, GR, JOH, VD and NH. Guarantor: GR.
Competing interests None declared.
Ethics approval Hamburg Ethical Committee.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement The authors have full control of all primary data and agree to allow BJO to review the data upon request.
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