The study authors sought to investigate the possible effects of circadian photoentrainment following cataract. This was a randomised clinical trial, where 76 eyes of 76 patients (with bilateral cataract) were randomised to blue-blocking or neutral intraocular lenses (IOLs). Outcome measures included activation of intrinsic photosensitive ganglion cells to blue light, actigraphy to analyse circadian rhythms, 24-hour salivary melatonin measurements, and the Pittsburgh Sleep Quality Index. Most of the circadian and sleep-specific actigraphy parameters were not significantly altered after surgery, and thus the study authors concluded that cataract surgery was unlikely to significantly affect sleep. Additionally, there was no significant difference between blue-blocking and neutral IOLs – IOL selection should therefore be based on the patient’s clinical need rather than concern over the possibility of sleep being adversely affected.