One of the most commonly performed surgical procedures in the world is cataract surgery: the removal of patient’s clouded natural crystalline lens, and its replacement with a synthetic intraocular lens (IOL). The procedure has been successfully performed for more than 65 years. Over that time, many new IOLs have been developed, varying by design, material, implantation location and fixing method. Some IOLs were successful, others not; clinical evaluation, for the most part, made that distinction.

We searched clinicaltrials.gov for: ("intraocular lens" OR "implantable collamer lens" OR toric OR multifocal) NOT ("contact lens" OR "contact lenses"), and exported the entire dataset as tab-separated values, for import into and analysis within Microsoft Excel 2013. Inappropriate records (mostly related to multifocal tumors in breast cancer) were removed, and the full text of each record examined for additional details to be recorded into the spreadsheet (such as the type of evaluation performed, or the manufacturer of every IOL mentioned, where possible).