Refractive Outcomes for Cataract Surgery With Toric Intraocular Lenses at a Veterans Affairs Medical Center
Background
Methods: A retrospective chart review of patients who received cataract surgery with toric IOLs from November 2013 to May 2018 was conducted. The Holladay 2 and Barrett toric IOL formulae were used to predict the postoperative refraction for each cataract surgery. The main outcome measures were best-corrected visual acuity (BCVA) and the difference in cylinder between the preoperative and postoperative manifest refractions. The accuracy of each biometric formula was also assessed using 2-tailed t tests of the mean absolute error, and subgroup analyses were conducted for short, medium, and long eyes.
Results: Of 325 charts reviewed, 283 patients met the inclusion criteria; 87% (248/283) of these surgeries were performed by resident surgeons. The median postoperative BCVA was 20/20, and 92% of patients had a postoperative BCVA of 20/25 or better. There was no statistically significant difference in mean absolute error between the 2 formulae for the entire axial length range ( P = .21), as well as the short ( P = .94), medium ( P = .49), and long axial length ( P = .08) groups.
Conclusions: To our knowledge, this is the largest study that compared the performance of the Barrett toric and Holladay 2 formulae and the first that made the comparison in a teaching hospital setting. This study suggests that the 2 formulae have similar refractive outcomes across all axial lengths.
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.
