The article discusses a 2011 study by lead author Nienke Visser on a three-step ink marking procedure for toric pseudophakic and phakic intraocular lens (IOL) implantation. Results of the study showed that the method produces significant errors related to toric IOL alignment. Study authors note that mean alignment error was around 5°. Visser states that each degree of misalignment plays a role on residual astigmatism.