Association of Intraocular Cataract Lens Replacement With Circadian Rhythms, Cognitive Function, and Sleep in Older Adults

IMPORTANCE: Cataract is associated with a progressive decline in light transmission due to the clouding and yellowing of the natural crystalline lens. While the downstream effects of aging lenses include long-term disruption of circadian rhythms, cognitive function, and sleep regulation, it remains unknown whether there is an association of intraocular cataract lens (IOLs) replacement with circadian rhythms, cognition, and sleep. OBJECTIVE: To test whether IOL replacement (blue blocking [BB] or ultraviolet [UV] only blocking) in older patients with previous cataract is associated with the beneficial light effects on the circadian system, cognition, and sleep regulation. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional study at the Centre for Chronobiology, University of Basel in Switzerland from February 2012 to April 2014, analyzed between June 2012 and September 2018. Sixteen healthy older controls and 13 patients with previous cataract and IOL replacement participated without medication and no medical and sleep comorbidities. EXPOSURES: Three and a half hours of prior light control (dim-dark adaptation), followed by 2 hours of evening blue-enriched (6500 K) or non–blue-enriched light exposure (3000 K and 2500 K), 30 minutes in dim post–light exposure, 8 hours of sleep opportunity, and 2 hours of morning dim light following sleep. MAIN OUTCOMES AND MEASURES: Salivary melatonin, cognitive tests, and sleep structure and electroencephalographic activity to test the association of IOLs with markers of circadian rhythmicity, cognitive performance, and sleep regulation, respectively. RESULTS: The participants included 16 healthy older controls with a mean (standard error of the mean [SEM]) of 63.6 (5.6) years; 8 women and 13 patients with previous cataract (mean [SEM] age, 69.9 [5.2] years; 10 women); 5 patients had UV IOLs and 8 had BB IOLs. Patients with previous cataract and IOLs had an attenuated increase in melatonin levels during light exposure (mean [SEM] increase in the BB group: 23.3% [2.6%] and in the UV lens group: 19.1% [2.1%]) than controls (mean [SEM] increase, 48.8% [5.2%]) (difference between means, 27.7; 95% CI, 15.4%-41.7%; P