Eyeworld

EW RESIDENTS 72 June 2016 use of toric IOLs. This imprecision is in both the preoperative measure- ment of toric IOL power and in the standard eye marking techniques for proper toric IOL alignment. Intraop- erative wavefront aberrometry with the third generation ORA system provides 1 method to improve the precision of toric IOL selection. It remains to be seen whether this new system offers significant benefit to the patient in terms of spectacle independence or visual quality of life measures. These advantages will need to be balanced with the cost of the device and increased intraopera- tive time. EW References 1. Hemmati HD, et al. Intraoperative wave- front aberrometry in cataract surgery. Semin Ophthalmol. 2012;27:100–106. 2. Chen M. Correlation between ORange intraoperative refraction and 1-week postcat- aract surgery autorefraction. Clin Ophthalmol. 2011;5:197–199. 3. Donnenfeld ED, et al. Intraoperative wave- front aberrometry during cataract surgery as a predictor of postoperative refractive results. 2008 ASCRS•ASOA Symposium & Congress, abstract 415280. 4. Donnenfeld ED. Initial experience with the ORange intraoperative wavefront aberrom- eter for use in limbal relaxing incisions and toric IOLs. 2009 ASCRS•ASOA Symposium & Congress, abstract 559731. 5. Solomon RD, et al. Real-time intraoperative aberrometry to improve IOL power selection in eyes having cataract surgery after refractive surgery. 2010 ASCRS•ASOA Symposium & Congress, abstract 738539. 6. Barsam A. Real-time intraoperative aber- rometry during cataract surgery to improve IOL power selection following LASIK and PRK. 2011 ASCRS•ASOA Symposium & Congress, abstract 982667. 7. Tran D. Use of intraoperative aberrometry for accommodating IOL power selection in post-LASIK cataract patients. 2011 ASCRS• ASOA Symposium & Congress, abstract 983695. 8. Huelle JO, et al. First clinical results on the feasibility, quality and reproducibility of aberrometry-based intraoperative refraction during cataract surgery. Br J Ophthalmol. 2014;98:1484–1491. 9. Fram NR, et al. Comparison of intraoper- ative aberrometry, OCT-based IOL formula, Haigis-L, and Masket formulae for IOL power calculation after laser vision correction. Ophthalmology. 2015;122:1096–1101. 10. Visser N, et al. Comparability and repeat- ability of corneal astigmatism measurements using different measurement technologies. J Cataract Refract Surg. 2012;38:1764–70. Contact information Mieler: wmieler@uic.edu by the multicenter study design, could also account for the differenc- es in outcomes. Interestingly, although one of the motivations for this study was the questionable precision of alignment with standard toric IOL markers, the authors did not include an analysis that addressed whether alignment was responsible for the difference in postoperative astigmatism between the 2 groups. Instead, they reported differences in postop cylinder power. Because intraoperative aberrometry reported- ly accounts for the anterior and pos- terior curvature of the cornea, while the preoperative measurements in the control cohort used standard biometric techniques—which make assumptions about the posterior cor- neal curvature—further analysis is warranted. For example, it is unclear whether the better postoperative astigmatism in the test cohort was due to the intraoperative measure- ment in an aphakic eye (influenced by surgical factors such as corneal incision, wound edema, etc.) or whether the total corneal power was simply more accurately calculated. The authors' passing reference to an earlier study that demonstrated a significant difference in astigma- tism measurements obtained with the Pentacam (Oculus, Arlington, Washington) and those obtained with several automated keratometers is revealing. 10 It would have been helpful if the current study had compared the postoperative astigma- tism in eyes in the test cohort with another cohort that had undergone preoperative IOL measurements with an imaging system that directly measures the anterior and posterior corneal curvatures. While the reduction in post- operative astigmatism between test and control groups was small but statistically significant, there was no difference in uncorrected postoper- ative visual acuity. Median uncor- rected visual acuity (Snellen equiv- alent) was 20/21 in the test cohort and 20/22 in the control. Although the authors suggest a trend toward improvement in the uncorrected visual acuity in the test group and there was a somewhat larger number of test group eyes that experienced 20/20 vision or better, the authors made no claim whether these results were statistically significant. A number of technical points related to the use of the ORA system are missing from this study. First, while the authors state that there were no safety concerns in the study, there is no data comparing adverse intraoperative events or postop- erative complications. There is no discussion of the surgical obstacles introduced by the use of the ORA system as well: instrumentation employed, duration of operation, instrumentation cost, or challenges faced by the surgeon in employing the device. There is likewise no mention of the amount of time required by the surgeon to learn and effectively use the device to achieve reliable results. Finally, as the authors them- selves point out, primary outcomes were examined only at postoperative month 1, so it is unclear whether the differences in outcomes will be stable over longer time points. Certainly the stability of the post- operative outcome would be of high concern in choosing a new system that offered marginally more beneficial outcomes. It would also be interesting to know how gener- alizable this approach would be to post-refractive or ectatic corneas; a similar study would be clinically useful in this patient population because their aphakic measurements with intraoperative aberrometry may depart most from measurement by conventional methods. As our instrumentation and surgical technique for cataract sur- gery continue to improve, patient expectations for optimal refractive outcomes after cataract surgery continue to grow. Toric IOLs allow for correction of astigmatic error at the time of cataract surgery; howev- er, Woodcock et al have illustrated areas of imprecision in our current Review continued from page 71 Intraoperative aberrometry vs. standard preoperative biometry and a toric IOL calculator for bilateral toric IOL implantation with a femtosecond laser: One-month clinical study results Michael Woodcock, MD, Robert Lehmann, MD, Robert Cionni, MD, Michael Breen, OD, Maria Scott, MD J Cataract Refract Surg (June) 2016;42. Article in press Purpose: To compare astigmatic outcomes in subjects with bilateral cataracts undergoing toric intraocular lens (IOL) implantation with intraoperative aberrometry measurements in one eye, and standard power calculation and a toric IOL calculator with inked axis marking in the contralateral eye. Setting: Twelve sites in the U.S. Design: Prospective, multicenter, randomized, observer-masked, contralateral cohort study. Methods: The eye with more visually significant cataract was randomized to intraoperative aberrometry measurements or standard preoperative biometry and use of a toric calculator, with the contralateral eye automatically assigned to the other group. The primary effectiveness outcome was the proportion of eyes with postoperative refractive astigmatism ≤0.50 D at one month. Results: Of the 130 subjects (260 eyes) enrolled, 124 (248 eyes) were randomized and 121 (242 eyes) completed the trial. The percentage of eyes with astigmatism ≤0.50 D at 1 month was higher in the intraoperative aberrometry than in the standard group (89.2% vs. 76.6%, P=.006). Mean postoperative refractive astigmatism was lower in the intraoperative aberrometry group (0.29±0.28 D vs. 0.36±0.35 D, P=.041). Secondary effectiveness endpoints, including manifest refraction spherical equivalent prediction error, uncorrected distance visual acuity, and best corrected distance visual acuity, were similar. No safety outcomes were related to the intraoperative aberrometry system. Conclusions: Use of the intraoperative aberrometry system increased the proportion of eyes with postoperative refractive astigmatism ≤0.50 D and reduced mean postoperative refractive astigmatism at 1 month compared with standard methods. Other efficacy outcomes were similar. There were no safety concerns using the intraoperative aberrometry system.

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