Eyeworld

20 | EYEWORLD | SEPTEMBER 2019 ASCRS NEWS EYEWORLD JOURNAL CLUB by Tedi Begaj, MD, and Catherine Marando, MD in order to achieve the best binocular refractive outcome. In the current study, Turnbull and Barrett provide both insight and guidance for second eye refinement. They systematically assess the utility of derived mathematical adjustment factors to the second eye IOL power based on results from the first eye cataract surgery. Methods Turnbull and Barrett retrospectively analyzed two large datasets of patients who underwent DSBCS, one from Australia and one from the U.K. The Australian dataset included 139 pa- tients operated on by a single surgeon from Oc- tober 2015 to March 2018. AcrySof SN60WF or SN6ATX lenses (Alcon) were used. Biometry was captured with LENSTAR LS 900 (Haag- Streit), with refraction by a trained optome- trist at 4 weeks postop. Patients were excluded if there was a history of refractive surgery, additional combined surgeries (e.g., glaucoma or retinal surgery), or intra/postoperative compli- cations. The U.K. dataset included 605 patients who had undergone DSBCS between May 2012 and May 2017 at Southampton Eye Unit, Southampton, U.K. They utilized Tecnis ZCB00 lenses (Johnson & Johnson Vision) and an IOL- Master 500 (Carl Zeiss Meditec) for biometry. Inclusion and exclusion criteria of patients were similar; however, a single surgeon performed all cataract surgeries in the Australian cohort, while a multitude of surgeons, including trainees, performed surgeries in the U.K. cohort. Two methods were utilized for second eye refinement: (1) formula-specific and (2) pa- tient-specific. With the formula-specific meth- od, the authors performed a correlation analysis of the PE between the first and second eye for each individual formula (Barrett Universal II [BUII], Hoffer Q, Holladay, and SRK/T) and generated regression coefficients. They then retrospectively applied the formula-specific I n modern day cataract surgery, patients expect quick recovery and ideal refractive outcomes. The accuracy of intraocular lens (IOL) calculations has improved due to rapidly emerging technological advances in axial length measurement and keratometry. Advancements in IOL calculation formulas have increased success in reaching the desired target refraction. 1 Furthermore, new and emerg- ing IOL technologies, such as presbyopic and/ or astigmatic-correcting lenses, are available to help accomplish complex refractive goals with decreasing spectacle dependence. 2 However, despite the improvements seen over the last two decades, 10–20% of patients still exhibit greater or equal to 0.5 D of postoperative refractive error as compared to their predicted refractive outcome. 3 The difference between the predict- ed postoperative refraction (PPOR) and the achieved postoperative refraction is known as prediction error (PE). In the event that a cataract surgeon has not achieved target refraction in the first eye, how should they modify their IOL power selection when it comes time to operate on the second eye? Studies have shown that when extraneous sources of error have been excluded and both eyes have symmetric optical properties (e.g., corneal power, axial length), refining the second eye from the postoperative outcome of the first eye can decrease PE. 4,5 While no standard recommendation for second eye IOL correction exists in the U.S., the National Institute for Health and Care Excel- lence (NICE) in the U.K. currently recommends that a 50% correction factor be used for second eye calculations when the first eye has resulted in a refractive surprise. 6 At Massachusetts Eye and Ear (MEE), there is significant variability among the clinical faculty in refining IOL cal- culations for the second eye. However, delayed sequential bilateral cataract surgery (DSBCS) is the preferred approach by all faculty members Review of "Using the first eye prediction error in cataract surgery to refine the refractive outcome of the second eye" Mentor: Zhonghui Katie Luo, MD Chief resident: Grayson Armstrong, MD Contact information Lorch: Alice_Lorch@MEEI.HARVARD.EDU Alice Lorch, MD Program director Massachusetts Eye and Ear Harvard Medical School Boston

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