Purchase this article with an account.
Jan O Huelle, Vasyl Druchkiv, Nabil Habib, Gisbert Richard, Toam Katz, Stephan Linke; The end of preoperative biometry? Calculating intraocular lens power 'on the table' with two new intraoperative Hartmann-Shack aberrometry derived formulae. Invest. Ophthalmol. Vis. Sci. 2016;57(12):917.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To explore the application of intraoperative wavefront aberrometry (IWA) for aphakia based biometry introducing two new improved formulae. Further, to evaluate challenges to IWA presented by multifocal intraocular lens implants (mIOL). To test the recently postulated hypothesis that IWA outperforms conventional biometry.
During routine cataract surgery on 69 eyes (mean age 69.39±11.39 years), 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. Odds ratios and ANOVA were applied. The IOL that would have given the target refraction was back-calculated from postoperative manifest refraction at 3 months. Regression analysis was performed to generate two aphakic SE based formulae to predict this IOL. The accuracy of the formulae was determined by comparing them to conventional biometry and to published aphakia formulae. Results were compared to 10 additional patients (mean age 55.87±11.89 years) who received a mIOL implant.
In 41% of patients, three consecutive aphakia 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 -0.69D. Intraoperative biometry by our formula resulted in 25% and 53% of all cases ±0.50D and ±1.00D within target, respectively. A second formula taking axial length into account yielded corresponding ratios of 41% and 70%, respectively. The median absolute errors of prediction for our second formula and for conventional biometry were significantly different with 0.65D and 0.44D, respectively (p<0.05). Compared to the mIOL group, measurement success in pseudophakia was lower, IWA map quality significantly lower (p< 0.05) and accuracy of IOL calculation higher.
Inconsistent with the hypothesis, 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 successful readings. To enable reliable IOL calculation from IWA, measurement precision must be improved and aphakic IOL formulae need to be fine-tuned. Pseudophakic IWA measurements with mIOLs must be interpreted with caution.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
This PDF is available to Subscribers Only