IMPROVING OUTCOMES

Intraoperative aberrometry-assisted IOL power selection using streaming refractive data (ORA System with VerifEye, WaveTec Vision) provides a means for achieving improved refractive outcomes in cataract surgery, according to the results of a multicentre study presented by Dan B Tran MD, at the XXXI ESCRS Congress in Amsterdam. “When examining refractive outcomes in conventional cataract surgery, recent data show that when using preoperative measurements and conventional IOL power calculations, about 75 per cent of eyes are within 0.5 D of predicted postoperative spherical equivalent (SE) postoperatively. That is an improvement compared with previous reports in which this level of accuracy was achieved in less than 50 per cent of eyes. However, cataract surgeons would like their refractive outcomes to match those achieved with LASIK,” said Dr Tran, who was an investigator in the study, and is in private practice, Orange County, CA.

New data from a recent study looking at the recently released ORA System with VerifEye show that refractive outcomes are superior to those reported in the literature and significantly better than what surgeons would have gotten had they used their preoperative IOL power calculations, he reported. The study included data from 262 eyes operated on by 14 surgeons. Eligible eyes had no ocular disease or history of corneal refractive surgery and underwent uncomplicated cataract surgery. They were implanted with a variety of IOLs, including various multifocal and toric models. Preoperatively, surgeons calculated IOL power using their preferred formula, but the implant power was ultimately selected based on the aphakic refraction and the intraoperative aberrometer manufacturer’s proprietary formula. In toric IOL cases, the intraoperative aberrometer was also used to calculate cylinder power and to guide IOL rotation to minimise cylinder.

Dr Tran reported that in two-thirds of the cases, the surgeon changed the IOL power based on the intraoperative ORA measurement. In most of those cases, 82 per cent, the power change was 0.50 D, in 12 per cent of those cases, the change was 1.00 D or more. ORA confirmed the calculated preoperative power 34 per cent of the time. Mean absolute value of the prediction error (MAVPE), which was calculated using the difference between the predicted SE and actual refraction at one month, was significantly lower with the use of intraoperative aberrometry than had the surgeon’s preoperative determinations been used, 0.29 Â}0.20 D vs. 0.33 Â}0.27 D (P<0.03).

Distribution analyses showed 84 per cent of eyes were within 0.50 D of the predicted spherical equivalent after surgery whereas that proportion would have been 78 per cent had the surgeon’s preoperative calculation been used. When the refractive outcomes were analysed with the eyes categorised by IOL model, the results showed good accuracy across all platforms. Data from the subgroup of 33 eyes implanted with a toric IOL showed astigmatism was reduced from a mean of 1.94 D Â} 1.11 preoperatively to 0.39 D Â} 0.36 D at one month postoperatively.

Dan B Tran: danbtran@gmail.com