Eyeworld

109 EW RESIDENTS October 2018 For situations in which the preoperative and IA measurements differed in the study, the surgeons decided which lens would be chosen for the patient. It was in this area that the IA showed the largest (12.5%) benefit in achieving an APE <0.5 D (81.3% [10,385/12,779] vs. 68.8% [8794/12,779], P<.0001). A subgroup analysis of these cases has the potential to highlight particular patient populations that may benefit from the utilization of the tech- nology. Subgroups might include patients with increased age, extreme axial lengths, relative ptosis, in- creased density of cataract, irregular astigmatism, etc. In addition, the study design excluded patients with corneal scarring, ectasia, prior trans- plantation procedures, and those who were post-refractive surgery from the analysis, although these subgroups may benefit the most from this technology given known limitations of preoperative biometry in these complex cases. 5,6 The article by Cionni et al. is the largest study of IA to this point, providing insight into the precision of IA in IOL power calculation in cat- aract surgery. Despite its large sample size and the high degree of statistical significance in the study's endpoints, there remains uncertainty as to the clinical applicability of the findings. It is evident that the vast majority of cases likely received no additional benefit from the technology relative to standard preoperative biometry. Nonetheless, IA may ultimately prove useful in cases in which fur- ther subgroup analysis demonstrates a greater likelihood of benefit. Simi- lar to the way that aspirin is known to be of clear benefit in those with pre-existing cardiovascular disease but is not suggested for prophylactic thromboembolic prevention in the general population, targeting appro- priate patients for the use of IA may maximize clinical utility and patient outcomes while more responsibly utilizing healthcare dollars. EW percentage of eyes with an aberrom- etry APE <0.5 D than eyes with a preoperative calculation APE <0.5 D (81.9% [26,357/32,189] vs. 75.9% [24,437/32,189], P<.0001)." It would be interesting to know how many of the cases that fell outside of this APE <0.5 D metric were actually unhappy with their outcome. This information may also provide a measure of the clinical relevance of the authors' 0.5 D standard. The relevance of this small identified advantage of IA with respect to MAPE is further nuanced by limitations in current intraocular lens technology. While the study accounted for variability across manufacturers by limiting the data set to eyes with lenses manufactured by Alcon (the study's sponsor), there remains variability within a single manufacturer. IOL manufacturing tolerance, the internal variability of lens power within a single manu- facturer, is set by the International Organization for Standardization and ranges from 0.3 D to 1.0 D depending on total IOL dioptric power. 3 In addition, most man- ufacturers produce IOLs in 0.5 D increments. As such, the identified slightly greater precision offered by IA likely does not yet translate into a clinically tangible postoperative outcome with the currently avail- able IOL technology. In critically evaluating IA's role in routine cataract surgery, the cost-effectiveness of broadly adopt- ing this technology must also be considered. While no studies have yet been conducted to compare cost-effectiveness of IA in cataract surgery to conventional biometry, other technologies, such as femto- second laser-assisted cataract surgery (FLACS), have not been shown to be cost-effective compared to conven- tional surgery. 4 Moreover, IA adds extra steps to the surgical procedure, thus increasing operating room and anesthesia time and overall health- care resource utilization. 5. Koch DD. The enigmatic cornea and intra- ocular lens calculations: The LXXIII Edward Jackson Memorial Lecture. Am J Ophthalmol. 2016;171:xv–xxx. 6. Yesilirmak N, et al. Intraoperative wave- front aberrometry for toric intraocular lens placement in eyes with a history of refractive surgery. J Refract Surg. 2016;32:69–70. Contact information Veldman: pveldman@bsd.uchicago.edu References 1. Hatch KM, et al. Intraocular lens power selection and positioning with and without intraoperative aberrometry. J Refract Surg. 2015;31:237–42. 2. Limburg H, et al. Routine monitoring of visual outcome of cataract surgery. Part 2: Results from eight study centres. Br J Oph- thalmol. 2005;89:50–2. 3. www.iso.org/standard/55682.html 4. Abell RG, Vote BJ. Cost-effectiveness of femtosecond laser-assisted cataract surgery versus phacoemulsification cataract surgery. Ophthalmology. 2014;121:10–16. analysis comparing outcomes conventional preoperative planning" A large retrospective database analysis comparing outcomes of intraoperative aberrometry with conventional preoperative planning Robert Cionni, MD, Ramon Dimalanta, PhD, Michael Breen, OD, Cody Hamilton, PhD J Cataract Refract Surg. 2018;44(10):1230–1235. Purpose: Evaluate differences between the absolute prediction error using an intraoperative aberrometry (IA) device for intraocular lens power determination versus the error that would have resulted if the surgeon preoperative plan had been followed. Setting: Multiple centers in the United States. Design: Retrospective analysis of data collected using an IA device. Methods: The database information was limited according to predetermined inclusion/exclusion criteria. Primary endpoints included the difference between mean and median absolute prediction error with IA use versus preoperative calculation, and comparing the percentage of cases where the prediction error was <0.5 diopters (D). Results: A total of 32,189 eyes were analyzed. The IA mean absolute prediction error (MAPE) was lower than the preoperative calculation MAPE, 0.30 D (standard deviation [SD], 0.26) versus 0.36 D (SD, 0.32) (P<.0001). The aberrometry absolute median PE was lower than the preoperative calculation absolute median PE, 0.24 D vs. 0.29 D (P<.0001). There was a significantly greater percentage of eyes with an aberrometry APE <0.5 D than eyes with a preoperative calculation APE <0.5 D (81.9% [26,357/32,189] vs. 75.9% [24,437/32,189], P<.0001). In addition, in those cases where power of the lens implanted was different than the preoperatively planned lens power, significantly more eyes had an aberrometry APE <0.5 D (81.3% [10,385/12,779] vs. 68.8% [8794/12,779], P<.0001). Conclusions: In a database of more than 30,000 eyes, calculations incorporating IA outperformed preoperative calculations. The difference was more pronounced in those cases where the preoperatively planned lens power was different than the power of the lens implanted.

• Cover