Eyeworld

71 EW RESIDENTS June 2016 small (0.29±0.28 D vs. 0.36±0.35 D). While individual preferences and lifestyle concerns certainly must be accounted for when choosing a sur- gical approach for a given patient, one might question whether a differ- ence of ~0.07 D would be of much clinical significance in choosing be- tween these 2 methods in a general population. While the authors analyzed the proportion of eyes with ≤0.25 D, ≤0.50 D, ≤0.75 D, and ≤1.0 D postoperative refractive astigmatism in the test and control cohorts, the proportion was only statistically significantly higher in the ≤0.50 D group. Importantly, while the authors point out that a previous report considered a postoperative refraction of 1.0 D as the cutoff point for subjects to elect excimer enhancement, the authors in this current study failed to show a significant difference in the propor- tion of eyes with that refractive out- come. Additionally, there is no men- tion of the location of the surgical incisions used in this study, a factor which could potentially account for 0.25 to 0.50 D of astigmatic change. The nature of this study makes it impossible to blind the surgeons to the study groups, which may add performance bias to the study. Vari- ability in surgeon technique with preoperative markings, compounded BDVA were also similar in the test and control groups. The main strengths of this study are that it improves upon prior eval- uations of intraoperative aberrome- try with a larger subject population, is a clinically useful comparison to conventional methods, and is a ran- domized, multicenter, prospective, observer-masked design. Inclusion criteria were well defined, and attri- tion rate was low. While intraoper- ative aphakic refractive astigmatism was not measured in the control group, both test and control group eyes demonstrated similar profiles of preoperative astigmatism. The con- tralateral cohort structure allowed this study to control for intraopera- tive surgical variables that have been proposed to contribute to unreliable toric IOL power and placement calculations. The primary outcome highlight- ed by the study is that there was a larger fraction of astigmatic eyes with ≤0.50 D of postoperative refrac- tive astigmatism following cataract surgery with the intraoperative ab- errometer compared to the AcrySof IQ toric calculator. Although the fraction of eyes with this outcome was higher in the test group than in the control group, the difference (~12%) was rather modest. Likewise, the difference in the mean postop- erative astigmatism between the test and the control groups, while statistically significant, was rather for cylinder power selection and lens positioning, and standard IOL formulas were used to calculate the spherical power component of the lens. Surgeries were staggered by 1 week for each patient, and postop- erative exams were performed on day 1 and week 1 for both eyes, and month 1 after surgery on the second eye. Postoperative logMAR vision and refraction were evaluated in a masked fashion by a technician or optometrist. The primary effectiveness parameter was the proportion of eyes with postoperative refractive astigmatism ≤0.50 D at 1 month, while secondary endpoints included: the proportions of eyes at 1 month with refractive astigmatism ≤0.25 D, ≤0.75 D, and ≤1.0 D; the proportion of eyes meeting manifest refrac- tion spherical equivalent absolute prediction errors of ≤0.25 D, ≤0.50 D, ≤0.75 D, and ≤1.00 D relative to predicted postoperative spherical equivalent at 1 month; postoper- ative uncorrected distance visual acuity (UDVA); and postoperative best corrected distance visual acuity (BDVA). Of the 260 enrolled eyes, 248 eyes were randomized and 242 eyes completed the study. The proportion of eyes at 1 month with postopera- tive refractive astigmatism ≤0.50 D was higher in the test than in the control group (89.2% vs. 76.6%, P=.006). McNemar's test evaluating paired outcomes in individual subjects showed that 71.2% achieved postoperative refractive astigmatism ≤0.50 D in both eyes; 18.0% achieved ≤0.50 D in the test but not in the control eye; 5.4% achieved ≤0.50 D in the control but not in the test eye; and 5.4% failed to achieve ≤0.50 D in both eyes. Furthermore, the proportions of eyes with postoperative refractive astigmatism ≤0.25 D, ≤0.75 D, and ≤1.0 D were higher in the test than in the control group, and mean postoperative astigmatism was lower in the test than in the control group (0.29±0.28 D vs. 0.36±0.35 D, P=.041). While statistically insignifi- cant, the mean absolute value of the prediction error was slightly lower in the test than in the control group. Mean postoperative UDVA and determination after cataract surgery in patients with past LASIK surgery. 9 They found that there was no statis- tically significant difference among these methods, with mean absolute error of 0.37 D for the Haigis-L formula, 0.34 D for ORA, and 0.39 D for Optovue. 9 In "Intraoperative aberrometry vs. standard preoperative biome- try and a toric IOL calculator for bilateral toric IOL implantation with a femtosecond laser: One-month clinical study results," Woodcock et al report the astigmatic outcomes in subjects with bilateral cataracts undergoing toric IOL implantation with intraoperative aberrometry measurements in 1 eye, and stan- dard power calculation and a toric IOL calculator with inked axis mark- ing in the contralateral eye. This prospective, multicenter, random- ized, observer-masked, contralateral cohort study enrolled 130 patients (260 eyes) with bilateral cataracts scheduled for femtosecond laser-as- sisted cataract extraction combined with implantation of an AcrySof IQ aspheric toric IOL (Alcon) at 12 sites in the United States. Inclusion criteria consisted of: age >22 years with bilateral cataracts requiring the above mentioned procedures, clear ocular media other than cataract, and potential postoperative visual acuity of ≥0.2 logMAR (20/32). Exclusion criteria consisted of: prior limbal relaxing or arcuate inci- sions, complications during surgery unrelated to the investigational de- vice, lens/zonular instability, corneal diseases, amblyopia or degenerative retinal diseases. For each patient, the eye with a more visually significant cataract was first randomized to a test or control group, and the contralateral eye was assigned to the opposite group. Procedures for test eyes were based on intraoperative aberrometry measurements, while procedures for control eyes were based on standard preoperative biometry assessments, conventional IOL power formulas, the AcrySof IQ toric IOL calculator and ink marking for positioning. Intraoperative aberrometry mea- surements were obtained from the test group using the ORA system with VerifEye. The AcrySof IQ toric IOL calculator was used as a guide standard preoperative biometry and a toric IOL calculator femtosecond laser: One-month clinical study results" continued on page 72 " 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 intraoperative time. "

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