Intraoperative wavefront aberrometry (IWA)-based refraction may not provide reliable or consistent measurements and may not be ideally suited for guiding the surgical refractive plan for patients undergoing cataract surgery, according to a new prospective study. These findings were published online May 30 in the British Journal of Ophthalmology.
Jan O. Huelle, MD, from the Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Germany, and South West Peninsula Postgraduate Medical Education, School of Ophthalmology, Plymouth, United Kingdom, and coauthors recorded IWA in 74 eyes of 74 consecutive patients with a mean age of 69 years. Patients were admitted for cataract surgery between March 2010 and December 2010; the researchers excluded patients with ocular comorbidities. The baseline manifest refraction was +0.31 sphere (standard deviation [SD], 2.9) and −1.1 cylinder (SD, 1.05); the researchers attempted intraoperative measurements in aphakia and pseudoaphakia.
Of the 814 attempted IWA measurements, the researchers were able to obtain 462 (56.8%) wavefront maps, with the most successful results achieved in aphakia.
"We found it remarkable that in only 56.8% of intraoperative measurement attempts, a successful reading could be recorded. For those measurements that succeeded, we observed, as expected, a marked variation in WF quality across the single steps of cataract surgery, which may be caused by the unphysiological state of the eye during surgery," Dr. Huelle and coauthor Stephan J. Linke, MD, from Care Vision, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany, told Medscape Medical News.
The study authors propose 5 variables that may affect the quality of IWA measurements. These include:
topical anesthesia and corneal wound hydration,
hydration of the vitreous,
variable intraocular lens position,
patients' eye movements if only topical anesthesia is used, and
intraoperative state is not physiological.
Dr. Huelle and Dr. Linke noted that "to judge the success of an objective method of refraction, a 'gold standard' for comparison is required, which, to date, does not exist for intraoperative refraction," and that "future studies should seek to establish benchmarks in comparing different methods of intraoperative autorefraction in a randomized controlled trial."
"These findings are surprising because another competing technology with over 200 installed sites and over 100,000 reported postoperative outcomes shows outstanding predictability for [intraocular lens] power predictions based on aphakic readings, with a much lower standard deviation than included in this report," Roger Steinert, MD, an ophthalmologist and director of the Gavin Herbert Eye Institute at the University of California, Irvine, told Medscape Medical News. Dr. Steinert is a member of the scientific advisory board for WaveTec Vision, which makes the competing aberrometry device.
Dr. Steinert also points out that "the reader should be aware that this report is on a single device that is not currently marketed in the United States" and that "the surgeries and the readings are on only 74 patients dating back to 2010."
Although the authors of the present study acknowledge that IWA "offers promising applications during cataract surgery," given the study results, they recommend that "IWA is not relied on as the sole source for surgical decisions on astigmatic corrections but is, instead, always supplemented by conventional marking methods."
No financial support was received for this study. The authors have disclosed no relevant financial relationships. Dr. Steinert serves on the scientific advisory board for WaveTec Vision.
Br J Ophthalmol. Published online May 30, 2014. Abstract
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Cite this: Aberrometry-Based Refraction: Enough for Surgical Planning? - Medscape - Jun 18, 2014.