Wang-Koch Formula and IOL Power in Long Eyes

How can cataract surgeons reduce the likelihood of “hyperopic surprise” in eyes with long axial lengths? This was one of many topics discussed during Sunday morning’s Cataract Original Papers session.

Nicole R. Fram, MD, and her coauthors compared the ability of intraoperative aberrometry and 3 relatively new formulas—Wang-Koch, Olsen, and Barrett Universal II—to accurately predict IOL power in long eyes. They found that while all of the options performed well, the Wang-Koch formula proved to be statistically superior.

For this retrospective study, the researchers reviewed 52 eyes (39 patients) with axial lengths greater than 25 mm. All cataract extractions were performed through 2.2-mm incisions, and all of the surgeries were uncomplicated. Mean absolute error was 0.24 for intraoperative aberrometry, 0.12 for the Wang-Koch, 0.40 for the Olsen, and 0.35 for the Barrett Universal II.

In discussing the paper, Dr. Fram said that her takeaway from the research wasn’t necessarily that cataract surgeons should automatically rely on the Wang-Koch formula without considering other options. Instead, she said, it’s more a matter of consolidating information and having the highest possible level of confidence. “Aren’t we fortunate to have multiple formulas to compare and use to make a decision at the time of surgery?” she concluded. 

The report was selected as “best paper” during the Sunday session of Cataract Original Papers. Dr. Fram’s coauthors were Samuel Masket, MD, Li Wang, MD, PhD, and Douglas D. Koch, MD.—Jean Shaw

Financial disclosures. Dr. Fram—Abbott Medical Optics: L; Accutome: S; Alcon Laboratories: L; Allergan: C; Bausch + Lomb: L; Bio-Tissue: C; Shire: C; WaveTec Vision: S.

Disclosure key. C = Consultant/Advisor; E = Employee; L = Speakers bureau; O = Equity owner; P = Patents/Royalty; S = Grant support.