In this video from Dr. Osher's Video Journal of Cataract and Refractive Surgery, Dr. Graham Barrett explains how most third-generation optical formulas yield unpredictable results in cases of high myopia. The unpredictability, he argues, is due not to any vagary in axial measurement or keratometry, but to a fault in the formulas themselves. As opposed to the Haigis or SRK/T formula, Dr. Barrett's universal formula takes into account negatively powered IOLs and thus produces more predictable outcomes when used in high myopes.