Cataract surgery brings more light to the retina which may allow individuals to have a more normal circadian rhythm, manifesting in better sleep quality, and as a result, preventing sleep-modulated cognitive decline, according to Kimie Miyata, a staff ophthalmologist at Nara Medical University School of Medicine in Japan.
In her poster presentation at SLEEP 2015, the annual meeting of the Associated Professional Sleep Societies, Miyata observed that “in the general elderly population, cataract surgery is significantly associated with better objective sleep quality and cognitive function”.
She said sleep efficiency was 85.8 per cent in a fully adjusted multivariate analysis for patients who had undergone cataract surgery, compared with sleep efficiency of 84.4 per cent among patients who did not undergo the surgery (P=0.041). Additionally, the risk of being diagnosed with cognitive impairment was reduced 33 per cent in the patients who had undergone cataract surgery (P=0.047). The researchers corrected their findings for variables that included age, sex, body mass index, and sleep medication use.
Dr. Rob Weir, a sleep researcher and ophthalmologist at Oregon Health and Science University Portland told MedPage Today the findings made perfect sense because “cataracts tend to absorb blue light and blue light is the key wavelength for control of circadian rhythm”.
Nine hundred and thirty four healthy individuals who were at least 60 years old participated in the study, 154 of whom had had cataract surgery.
Objective sleep quality was measured at one minute intervals on two consecutive nights using an actigraph worn on the non-dominant wrist. The accuracy of self-reported cataract surgery was assessed. A slit-lamp examination was used to assess accuracy of self-reported cataract surgery. Cognitive impairment was assessed by clinical psychologists.