Abstract
Purpose: :
A non-visual photoreceptor (photoreceptive retinal ganglion cell - pRGC) provides light input to the circadian system, maintaining the sleep-wake cycle. This photoreceptor has maximal sensitivity at 480nm, corresponding to blue light. Cataract preferentially blocks out blue light, reducing pRGC input. Cataract surgery and clear (UV-blocking) lens implantation increases blue light transmission and may be expected to improve sleep patterns, as suggested by one clinical study. This observational study assesses sleep quality in a population with cataract, and investigates the effect of cataract surgery on sleep.
Methods: :
Patients with visually significant cataract proceeding to surgery were asked to complete the Pittsburgh Sleep Quality Index (PSQI) before surgery and 1, 6 and 12 months afterwards. The PSQI scores seven sleep components then gives a global score. Patient demographics, visual acuity (VA), coexistent ocular pathology, and whether surgery was to the first or second eye were recorded. PSQI component scores were compared for patients undergoing first vs second eye surgery, with good vs poor preoperative VA, and with normal vs abnormal preoperative global PSQI scores.
Results: :
400 patients have been recruited to date, including 130 with postoperative follow up data. The mean age was 74.1 years, and 57.9% of patients were female. The median preoperative VA (with both eyes open) was 6/7.5 (Snellen). 91.4% of patients underwent first eye surgery, and 74.6% had no coexistent ocular pathology. Patients with good preoperative VA scored significantly better on the PSQI than those with poor VA. Poorer scores were seen in second eye patients compared with first eye patients. Improved scores were seen following surgery. The difference was significant in a subgroup of patients with an abnormal preoperative global PSQI score.
Conclusions: :
Population demographics were as expected for cataract patients. Sleep problems were common in this population. Individuals with abnormal sleep scores prior to cataract surgery were more likely to report improved sleep after surgery, whereas those with normal preoperative scores showed no difference.
Keywords: cataract • circadian rhythms • melatonin