Elaine Tran and Kevin Tang are Medical Students; David Rivera and Jorge Rivera are Clinical Assistant Professors of Surgery (Ophthalmology); and Paul Greenberg is a Professor of Surgery (Ophthalmology); all at the Warren Alpert Medical School of Brown University in Providence, Rhode Island. Allison Chen is an Ophthalmology Resident at the Shiley Eye Institute, University of California San Diego Health in La Jolla. Michael Chen is a Student at Harvard University in Cambridge, Massachusetts. David Rivera and Jorge Rivera are Staff Ophthalmologists, and Paul Greenberg is Chief of Ophthalmology; all at the Providence Veterans Affairs Medical Center in Rhode Island. Correspondence: Paul Greenberg (paul_greenberg@brown.edu)
Author disclosures The authors report no actual or potential conflicts of interest for this article.
Disclaimer The opinions expressed herein are those of the authors and do not necessarily reflect those of Federal Practitioner, Frontline Medical Communications Inc., the US Government, or any of its agencies.
In 4 previous studies that compared the MAE of the Barrett and Holladay formulae for toric IOLs, the Barrett formula produced a lower MAE than the Holladay 2 formula.7,14-16 However, this difference was significant in only 2 of the studies, which had sample sizes of only 68 and 107 eyes.14,16 Furthermore, the Barrett toric formula produced the lower MAE for the entire AL range, though this was not statistically significant at our sample size. In addition, both formulae produced the lowest MAE in the long AL group and the highest MAE in the short AL group. The unique anatomy and high IOL power needed in short eyes may explain the challenges in attaining accurate IOL power predictions in this AL group.19,25
Limitations
The sample size of this study may have prevented us from detecting statistically significant differences in the performance of the Barrett and Holladay formulae. However, our findings are consistent with studies that compare the accuracy of these formulae in teaching and nonteaching hospital settings. Second, the study was conducted at a VA hospital, and a high proportion of patients were male; thus, our findings may not be generalizable to patients who receive cataract surgery with toric IOLs in other settings.
Conclusions
In a single VA teaching hospital, the Barrett and Holladay 2 biometric formulae provide similar refractive predictions for cataract surgery using toric IOLs. Larger studies would be necessary to detect smaller differences in the relative performance of the biometric formulae.
