Reduced post‐illumination pupil response in patients with mild‐moderate cataracts is associated with impaired sleep quality

Abstract

PurposeCataracts absorb light, especially in the blue‐range of the visible light spectrum, and reduce retinal illumination. Recent studies showed improved sleep and faster reaction times following cataract extraction. These non‐visual benefits are perhaps due to increased blue light transmission and melanopsin‐dependent photoreception. We compared visual function, pupil responses, sleep quality and sleep‐wake cycle in patients with cataracts and controls.Methods30 patients with cataracts and 22 age‐matched pseudophakic controls were tested during the winter season. Ophthalmologic examination with automated perimetry and optical coherence tomography was performed. Pupil responses were recorded to a 1s red or blue light having pre‐selected intensities. All participants completed a questionnaire for subjective sleep quality (Pittsburgh Sleep Quality Index; PSQI). They were asked to maintain a regular sleep‐wake rhythm with approximately 8 h of sleep. Rest‐activity cycles were recorded for one week by wrist worn activity watches.ResultsMean acuity was 1.0 ± 0.1 for both groups. The pupil contraction amplitude to dim blue light and the post‐illumination pupil response to bright blue light were significantly reduced in patients with cataracts (p < 0.05). This was associated with a significantly higher PSQI score relative to controls (p = 0.02), indicating impaired sleep, and a lower post‐illumination response to bright blue light (R = 0.43; p < 0.05). Sleep analysis from the activity watches revealed a significantly lower sleep efficiency in cataract patients than in controls (78.6 ± 8.3 vs. 83.2 ± 4.5; %; mean ± SD; p = 0.02).ConclusionsPatients with cataracts, not visually impaired, demonstrate reduced melanopsin activity, as assessed by the pupil response. This latter is correlated with impaired subjective sleep quality and greater sleep fragmentation.