Eyeworld

EYEWORLD JOURNAL CLUB by Caroline Wilson, MD, Austin Fox, MD, Lauren Hock, MD, Tony Chung, MD, Thomas Oetting, MD, residency program director, and the ophthalmology residents of the Department of Ophthal- mology and Visual Sciences, University of Iowa Hospitals and Clinics for study inclusion. Data on lens thickness, cen- tral corneal thickness, and white-to-white values were not used. The authors compared refractive calcula- tions from the following IOL formulas: Hoffer Q, Holladay 1, Haigis, SRK/T, Kane, Holla- day 2-AL, Olsen, Hill 2.0, and Barrett II. Lens constant optimization was performed for each formula. Prediction error (PE), including mean absolute prediction error (MAE), was calculated as the postoperative refraction by an optom- etrist minus the formula-predicted refractive outcome. The percentages of eyes that had a PE of ±0.25, ±0.50, and ±1 D were calculated for each formula. Sub-group analyses were per- formed based on axial eye length (short AL ≤22 mm, medium AL >22 mm to <26 mm, long AL ≥26 mm) and IOL type. Mean rank scores were calculated for each subgroup analysis. The differences in absolute prediction error between formulas was analyzed using the Friedman test. A p-value <0.05 was considered statistically significant. Results In the analysis of 10,930 eyes, the Kane formu- la had the lowest MAE compared to the other formulas (p<0.001). Using the Kane formula, the highest percentage of eyes (72%) had an actual refractive outcome within ±0.5 D of the predicted refractive outcome (71.2% for the Hill 2.0, 70.6% for the Olsen, 71% for the Holladay 2, 70.7% the Barrett II, 69.1% the SRK/T, 69% the Haigis, and 68.1% for the Hoffer Q). This was also the case for actual refractive outcome within ±0.25 and ±1 D of the predicted refrac- tive outcome. Not surprisingly, the other newer generation formulas (Hill 2.0, Olsen, Holladay 2-AL adjusted, and Barrett) outperformed the W hile everything else seems to get more complicated, intraoc- ular lens (IOL) calculations are becoming simpler. In the past, we have used a different IOL calculation formula depending on whether the eye undergoing cataract surgery was short, medium, or long. Here we review an impressive paper by Darcy et al. that demonstrates that the Kane formula is superior to other formulas in a huge data set across all axial eye lengths. The Kane formu- la is based on both theoretical models of the eye and on machine learning. Dr. Jack Kane has generously provided this formula online as a service to the ophthalmology community. During our review of this paper we had the op- portunity to meet Dr. Kane virtually and were very appreciative of the time he spent with us. Methods Dr. Kane's group retrospectively analyzed two large National Health Service (NHS) datasets in the United Kingdom. Uncompli- cated phacoemulsification cataract surgeries performed between May 2008 and November 2017 that included insertion of one of four IOL types (Alcon SA60AT, Rayner Super- flex 920H, Rayner C-Flex 970C, or Bausch + Lomb Akreos Adapt AO) and had preoperative biometry performed using partial coherence interferometry (IOLMaster, Carl Zeiss Meditec) were included. Cases with incomplete biome- try, corneal astigmatism >4 diopters (D), other corneal disease, previous vitrectomy, compli- cated cataract surgery, postoperative corrected distance visual acuity worse than 20/40, or postoperative complications were excluded. If patients underwent bilateral phacoemulsification cataract extraction, a single eye was randomly selected for study inclusion. Formal pre- and postoperative manifest refractions were required JANUARY/FEBRUARY 2020 | EYEWORLD | 21 Review of "Assessment of the accuracy of new and updated IOL power calculation formulas in 10,930 eyes from the UK National Health Service" continued on page 22 Caroline Wilson, MD Ophthalmology resident and first author on the review University of Iowa Iowa City, Iowa Several new IOL formulas have been introduced, in- cluding some that incorpo- rate artificial intelligence. I asked the Iowa residents to review this study from the January JCRS that compares their performance to other leading formulas, including the Barrett Universal. —David F. Chang, MD, EyeWorld Journal Club Editor

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