Blue-light-blocking intraocular lens implantation improves the sleep quality of cataract patients

Evening wear of blue-blocking glasses for sleep and mood disorders: a systematic review

Blue-blocking glasses, also known as amber glasses, are plastic glasses that primarily block blue light. Blue-blocking glasses have been studied as a sleep intervention for insomnia, delayed sleep-phase disorder, shift work, jet lag, and nonpathologic sleep improvement. Blue-blocking glasses have also been studied as a treatment for bipolar disorder, major depression, and postpartum depression. Blue-blocking glasses improve sleep by inducing dim-light melatonin onset by reducing activation of intrinsically photosensitive retinal ganglion cells (ipRGCs) which are most sensitive to blue light and are a major input for circadian regulation; their mechanism for mood regulation is unclear but may be similar to that of dark therapy for bipolar disorder where patients are kept in darkness for an extended period every night. A systematic search of the scientific literature identified a total of 29 experimental publications involving evening wear of blue-blocking glasses for sleep or mood disorders. These consisted of 16 randomized controlled trials (RCTs) published in journals with a total of 453 patients, 5 uncontrolled trials, 1 case series, 1 case study, and 6 abstracts from conference proceedings. Only 1 case study and 1 RCT were for acutely manic patients but both found substantial decreases in manic symptoms with the use of blue-blocking glasses; these give preliminary clinical evidence of efficacy that makes blue-blocking glasses a high-yield intervention to study for bipolar disorder. Findings in the 3 publications for major depression and postpartum depression were heterogeneous and conflicting as to their efficacy. Out of the 24 publications focusing on sleep, there was substantial evidence for blue-blocking glasses being a successful intervention for reducing sleep onset latency in patients with sleep disorders, jet lag, or variable shift work schedules. Given the well-established biological mechanism and clinical research showing that blue-blocking glasses are effective for inducing sleep, they are a viable intervention to recommend to patients with insomnia or a delayed sleep phase.

Effect of evening blue light blocking glasses on subjective and objective sleep in healthy adults: A randomized control trial

OBJECTIVES

Evening blue light has been shown to suppress melatonin, which can negatively impact sleep quality. The impact of evening blue light blocking (BLB) interventions on sleep remains ambiguous due to lack of randomized control trials. The present study tests the hypothesis that BLB glasses improve subjective and objective sleep in a population of healthy adults.

DESIGN

Two-week, randomized, controlled, crossover design.

SETTING

At-home testing of individuals in Michigan and Montana.

PARTICIPANTS

Twenty healthy adults (11 men, 9 women, age: 32 ± 12, body mass index: 28 ± 4 kg/m²).

INTERVENTION

Following a 1-week run-in baseline (ie, no glasses), participants were randomized to 1-week of BLB or control (ie, clear lens) glasses. Upon finishing the 1-week intervention, participants crossed over to the opposite condition. In both conditions, glasses were worn for 7 consecutive days from 6 PM until bedtime.

MEASUREMENTS

Objective sleep parameters were obtained using wrist actigraphy. Subjective sleep measures were assessed using sleep diaries. Karolinska Sleep Diaries were used to assess perceived sleep quality.

RESULTS

BLB reduced subjective sleep onset (21 ± 28 vs 24 ± 21 minute, P = .033) and awakenings (1.6 ± 1.0 vs 2.2 ± 1.0 awakenings, P = .019) compared to the control condition. In contrast, objective measures of sleep were not significantly impacted. In fact, our primary outcome variable of total sleep time (TST) tended to be paradoxically shorter in the BLB condition for both subjective (468 ± 45 vs 480 ± 48 minute, P = .066) and objective (433 ± 40 vs 449 ± 39 minute, P = .075) TST.

CONCLUSIONS

Blue light blocking glasses did not improve objective measures of sleep time or quality in healthy adults.

Association between the pattern of mobile phone use and sleep quality in Northeast China college students

OBJECTIVES

Currently, mobile penetration is high amongst college students. The aims of this study were to investigate the characteristics of mobile phone use and to explore the influence of mobile phone use characteristics on sleep quality amongst college students.

METHODS

From December 2016 to January 2017, we collected mobile phone use characteristics and sleep quality data using the Pittsburgh Sleep Quality Index (PSQI) and standardised questionnaires that were answered by 4500 medical university students in Liaoning Province (actual response rate of 94%, n = 4234 college students). This study used the SPSS 21.0 software to establish the database and perform the statistical analysis.

RESULTS

One hundred percent of the college students had mobile phones and used mobile phones for entertainment (91%), work (51%), obtaining information (61%), and other purposes (23%). Additionally, there was a statistically significant difference in the PSQI score between students who held the phone at a distance of more than 10 cm from their eyes and those who held it a distance of less than 10 cm (P = 0.002). Multiple logistic regression analysis showed that the risk of poor sleep quality was 1.21-1.53 times higher for those who spent more than 5 h a day using their phones and 1.41-1.59 times higher for those who used their phones for more than half an hour before going to bed when the lights were off.

CONCLUSIONS

Daily cumulative mobile phone use and use with the lights off before sleep are associated with poorer sleep quality.

Drug-loaded and Blue-ray Filtered Hydrogel as a Potential Intraocular Lens for Cataract Treatment

Background:

Indomethacin (IND) is a class of non-steroidal, anti-inflammatory drugs, which is used to treat various kinds of ocular inflammation, and has been reported to prevent posterior capsule opacification (PCO) by inhibiting the mitosis and collagen synthesis of human lens epithelial cells (LECs). In addition, the specific absorption spectrum of indomethacin shows the effect of absorbing short-wavelength blue-violet light.

Objective:

We prepared an indomethacin-loaded hydrogel as a potential intraocular lens (IOLs) material to prevent endophthalmitis, PCO and filter harmful blue light.

Methods:

Indomethacin prodrugs (HEMA-IND) (HI) were prepared by esterification of indomethacin and 2-hydroxyethyl methacrylate (HEMA), and poly (HEMA-co-MAA-co-MMA-co- HI) (HAMI) hydrogels were prepared by free-radical polymerization of 2-hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA), methacrylic acid (MAA) and HI. The physical and chemical properties of obtained hydrogel were detected, including optical, morphology, thermomechanical and surface properties, equilibrium water content, drug release behaviors and cytotoxicity.

Results:

HAMI hydrogels can filter harmful short-wavelength blue light and show other necessary properties like visible light transparency, glass transition temperatures, mechanical strength, and biocompatibility for making intraocular lenses. Meanwhile, MAA increases the hydrophilicity of the hydrogels, resulting in a lower water contact angle and controllable drug release from the hydrogels.

Conclusion:

In summary, HAMI hydrogels show a great potential as IOL biomaterials that can maintain the sustained release of indomethacin and filter harmful blue light after cataract surgery.

Lay Summary:

People with cataract surgery can be at high risk of postoperative complications, such as PCO and postoperative endophthalmitis. Moreover, early IOLs allowed all ultraviolet (UV) and visible light to pass through retina without restriction, thus to damage the retina and the retinal pigment epithelium, which may lead to retinopathy and age-related macular degeneration (AMD). Herein, we sought to design and prepare a kind of IOLs loaded with indomethacin to mitigate those postoperative complications and filter harmful blue light to improve the treatment prognosis.

Effects of ultraviolet and blue-light filtering on sleep: a meta-analysis of controlled trials and studies on cataract patients

PURPOSE

Two types of intraocular lenses (IOLs), namely ultraviolet-filtering IOL (UVF-IOL) and blue-light-filtering IOL (BF-IOL), are used to replace the aging lens in cataract patients. This provides a clinical scenario to investigate the BF and UVF effects on circadian rhythm. We revisited this topic and conducted an updated meta-analysis investigating the effects of UVF-IOL and BF-IOL on sleep quality.

METHODS

A literature search was conducted using the PubMed, Embase, and Cochrane Library databases, and finally, four randomized controlled trials, one nonrandomized controlled study, and two cohort studies were included in this meta-analysis.

RESULTS

The fixed-effect model revealed a significantly larger sleep quality improvement in the UVF-IOL group than in the BF-IOL group (standard mean difference [SMD] = 0.10, 95% confidence interval [CI]: 0.00-0.21) at 3-8 weeks but not 7-12 months after IOL implantation (SMD = 0.03, 95% CI: -0.08 to 0.13). The random effects model revealed no difference between groups at 3-8 weeks (SMD = 0.16, 95% CI: -0.07 to 0.39) and 7-12 months (SMD = 0.03, 95% CI: -0.08 to 0.13) after IOL implantation.

CONCLUSIONS

Our study found some weak evidence supporting that UVF-IOL implantation demonstrated a greater improvement in subjective sleep quality than the BF-IOL implantation only in a shorter period but not in a longer period. More trials should be conducted before further recommendations. Nevertheless, our study provides some insights into the effects of short wavelength electromagnetic radiation on the circadian rhythm. PROSPERO registration number: CRD42019128832.

The effect of cataract surgery on sleep quality: a systematic review and Meta-analysis

AIM

To evaluate the effect of cataract surgery on sleep quality and to compare the difference between ultraviolet-blocking clear intraocular lens (UVB-IOL) and blue-filtering intraocular lens (BF-IOL) implantation.

METHODS

Electronic search was performed of PubMed, MEDLINE, Embase and the Cochrane Library up to January 2016. Studies were eligible when they evaluated the sleep quality before and after cataract surgery by Pittsburgh sleep quality index (PSQI). A random/fixed-effects Meta-analysis was used for the pooled estimate. Heterogeneity was assessed with the I² test.

RESULTS

Six studies were selected from 5623 references. Cataract surgery significantly reduced the PSQI scores at postoperative 0-3mo [mean difference (MD) =-0.62, 95%CI: -1.14 to -0.11, P=0.02, I²=66%] and 3-12mo (MD=-0.32, 95%CI: -0.62 to -0.02, P=0.04, I²=0), respectively. Considering different intraocular lens (IOL) implantations, relative post-operative PSQI reduction was found for both UVB-IOL and BF-IOL, but a significant reduction was detected only for UVB-IOL. No significant difference was found with the effect of BF-IOL vs UVB-IOL on sleep quality.

CONCLUSION

This study found that cataract surgery significantly improved the PSQI score-derived subjective sleep quality irrespective of the IOL type implanted. These findings highlight a substantial benefit of cataract surgery on systemic health with photoreceptive restoration in addition to visual acuity improvements.

The effect of blue-blocking and neutral intraocular lenses on circadian photoentrainment and sleep one year after cataract surgery

PURPOSE

To compare the long-term effect on circadian photoentrainment and sleep in patients implanted with neutral and blue-blocking intraocular lenses 1 year after cataract surgery.

METHODS

Randomized, controlled trial involving 67 patients with age-related cataract. Intervention was cataract surgery with implantation of either a neutral or a blue-blocking intraocular lens (IOL). Main outcome was activation of the intrinsically photosensitive retinal ganglion cells (ipRGC) measured by chromatic pupillometry. The circadian rhythm was analysed by 24-hr melatonin profiles and actigraphy; the latter was also used to determine objective sleep quality. The Pittsburgh Sleep Quality Index determined subjective sleep quality.

RESULTS

One year after surgery, peak melatonin concentration was 3.3 pg/ml (95% CI, 2-5.5) corresponding to 50% lower for the participants allocated to blue-blocking IOLs compared with participants allocated to neutral IOLs. Compared with preoperative levels, the ipRGC response had increased by 13.7% (95% confidence interval [CI], 3.2-22.6) 1 year after surgery. Objective sleep quality was also improved as the time of wakefulness after sleep onset had improved by 5 min (95% CI, 1-10) for the entire population while sleep efficiency had increased by two percentage points (95% CI, 0.42-3.65) although exclusively, for the participants allocated to blue-blocking IOLs.

CONCLUSION

Blue-blocking IOLs increased sleep efficiency but lowered nocturnal melatonin secretion compared with neutral IOLs. Cataract surgery improved the response of ipRGCs and sleep quality. However, the effect of cataract surgery on sleep quality may be unrelated to circadian photoentrainment.

Impact of blue-light filtering intraocular lens implantation on the quality of sleep in patients after cataract surgery

BACKGROUND

There are 2 main types of intraocular lens (IOL) currently implanted in patients after cataract surgery. Till now, we do not know exactly what the effect of intraocular lens implantation will be on the quality of sleep after cataract surgery.

METHODS

The binocular BF-IOL (BF-IOL Groups) and UVB-IOL (UVB-IOL Groups) implantations were performed in 60 and 59 cataract patients, respectively. Pittsburgh Sleep Quality Index (PSQI) questionnaires were administered to evaluate the quality of sleep in patients preoperatively, 1 month (1 m) and 12 months (12 m) postoperatively. Independent sample test and χ test were used to evaluate the difference between the 2 groups; one-way ANOVA was used to evaluate the difference preoperatively and postoperatively in each group. The rank sum test was used for statistical analysis of 7 independent sleep components in PSQI.

RESULTS

As compared to preoperatively, the PSQI overall scores in both groups improved significantly postoperatively (P = 0.00 at 1 m and 12 m). Among the 7 components of PSQI, 2 of them (sleep latency and daytime dysfunction) improved greatly postoperatively in both groups (P< 0.05). Although the improvement of PSQI overall score in the UVB-IOL group was greater than that in the BF-IOL Group only at early time (1 m) postoperatively (P = 0.00), but not late time (12 m, P > 0.05) after the cataract surgery.

CONCLUSION

The sleep quality of cataract patients improved after IOL implantation, regardless of the type of IOL, suggesting that BF-IOL might serve as an alternative to conventional UVB-IOL without a detrimental effect on quality of sleep after cataract surgery.

Associated depression in pseudophakic patients with intraocular lens with and without chromophore

BACKGROUND

With aging, the crystalline lens turns yellowish, which increases the absorption of wavelengths in the blue electromagnetic spectrum, reducing their photoreception in the retina. Since these wavelengths are the main stimulus in the regulation of the circadian rhythm, progressive reduction in their transmission is associated with chronic sleep disturbances and depression in elderly patients. Cataract extraction improves circadian photoreception at any age. However, lenses that block blue waves have 27% to 38% less melatonin suppression than lenses that block only ultraviolet (UV) rays.

PURPOSE

To assess the depression symptoms in subjects who have had bilateral phacoemul-sification and intraocular lens (IOL) implants, one group with yellow chromophore IOLs and the other group with transparent IOLs were compared.

SETTING

Association to Prevent Blindness in Mexico (APEC), Hospital "Dr Luis Sánchez Bulnes".

DESIGN

This was an observational, cross-sectional, and single-center study.

MATERIALS AND METHODS

Twenty-six subjects between 60 and 80 years of age, with a history of bilateral phacoemulsification and placement of the same type of IOL in both eyes from 4 to 12 months prior to the study, who attended the follow-up visits and agreed to participate in this study, and provided signed informed consent were included in the study. They were asked to answer the short version of the 15-item Geriatric Depression Scale.

RESULTS

The average age of the study participants was 72.5±5.94 years. The group without chromophore included 46.1% (n=12) of the patients and the group with chromophore included 53.9% (n=14) of the patients (P=0.088).

CONCLUSION

In the group of patients with IOLs that block the passage of blue light, the depression rate was 21.4%, a rate similar to that observed in the elderly population, whereas no patients in the group with transparent IOLs had depression.

Motor function benefits of visual restoration measured in age-related cataract and simulated patients: Case-control and clinical experimental studies

The aim of the present study was to measure gait velocity in cataract and simulated patients. The study was performed on 239 cataract patients, 115 age-matched subjects, and 11 simulated patients. We measured gait velocity and analyzed gait using a three-dimensional motion analysis system. Mean gait velocity before and 2 and 7 months after cataract surgery was 0.91 ± 0.19, 1.04 ± 0.21, and 1.06 ± 0.21 m/s, respectively, for males and 0.84 ± 0.22, 0.91 ± 0.24, and 0.92 ± 0.25 m/s, respectively, for females. The increase after surgery was significant in both groups at 7 months (P < 0.05). Gait velocity was significantly slower in cataract patients compared with controls before surgery, but no longer different after surgery. In simulated patients, mean velocity was 87.0 ± 11.4% of normal vision with a 3° visual field and 92.4 ± 12.3% of normal when counting fingers. Initial velocity was 89.1 ± 14.6% of normal vision with a 3° visual field and 92.7 ± 11.6% of normal when counting fingers. There was a significant difference between normal and impaired visual function (P < 0.05). The results demonstrate the close relationship between visual function and gait in cataract patients and simulated patients.

Comparisons of Objective Sleep Quality Between Elderly Individuals With and Without Cataract Surgery: A Cross-Sectional Study of the HEIJO-KYO Cohort

Background

Cataract surgery (CS) drastically increases the capacity for light reception to the retina. Several previous studies have suggested the beneficial effect of CS on subjectively measured sleep quality; however, the association between CS and objectively measured sleep quality remains uncertain.

Methods

To evaluate the association between CS and objectively measured sleep quality in home settings, we conducted a cross-sectional study in 1037 elderly individuals (mean age, 71.9 years). We evaluated actigraphically measured sleep quality, urinary 6-sulfatoxymelatonin excretion, and ambulatory light levels, in addition to CS status.

Results

The CS group (n = 174) showed significantly higher sleep efficiency and shorter wake after sleep onset than the no CS group (n = 863), even after adjustment for age, gender, body mass index, current smoking status, alcohol consumption, hypertension, diabetes, sleep medication, bedtime, rising time, daytime physical activity, daytime and nighttime light exposure, and urinary 6-sulfatoxymelatonin excretion (sleep efficiency: 85.8% in the CS group vs 84.4% in the no CS group, P = 0.042; wake after sleep onset: 45.7 min vs 50.6 min, respectively, P = 0.033). In contrast, urinary 6-sulfatoxymelatonin excretion, sleep onset latency, total sleep time, and sleep-mid time did not differ significantly between the CS and no CS groups.

Conclusions

Among a community-dwelling elderly population, CS is significantly associated with objectively measured sleep quality, but urinary levels of melatonin metabolite do not differ between individuals with and without CS. These associations are independent of daily light exposure profiles.

Rejuvenation effects of cataract surgery with ultraviolet blocking intra-ocular lens on circadian rhythm and gait speed

BACKGROUND

Previously, we reported improvements in sleep quality and gait speed after implantation of a yellow-colored, blue light-blocking intra-ocular lens (IOL). This study evaluated systemic health parameters for 7 months after cataract surgery with implantation of a clear, ultraviolet (UV)-blocking IOL.

METHODS

A total of consecutive 71 patients (average age 74.1 years) underwent cataract surgery with the implantation of a clear, UV-blocking IOL. Participants were evaluated using the Pittsburgh Sleep Quality Index (PSQI) and the National Eye Institute Visual Function Questionnaire (VFQ-25) before and at 2 and 7 months after surgery. Four-meter gait speed was also determined. The metabolic parameters of serum glycated hemoglobin (HbA1c), triglycerides (TGs), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) were tested.

RESULTS

The pre-operative and post-operative (2 and 7 months after surgery) results were 66.4±16.5, 79.5±12.6, and 81.0±13.0 for VFQ-25 score, 5.7±3.5, 5.1±3.1, and 4.8±2.9 for PSQI, and 0.90±0.22, 0.91±0.22, and 0.92±0.22 meters/sec for gait speed. Significant improvements following surgery were noted in the VFQ-25 score for all cases and in the PSQI for poor sleepers (preoperative PSQI >5.5) (P<0.05, paired t-test). The gait speed and metabolic parameters showed no significant changes.

CONCLUSIONS

Cataract surgery with implantation of an UV-blocking clear IOL has the potential for improving circadian rhythm and systemic health parameters.

The effect of blue-blocking intraocular lenses on circadian biological rhythm: protocol for a randomised controlled trial (CLOCK-IOL colour study)

INTRODUCTION

Blue light information plays an important role in synchronising internal biological rhythm within the external environment. Circadian misalignment is associated with the increased risk of sleep disturbance, obesity, diabetes mellitus, depression, ischaemic heart disease, stroke and cancer. Meanwhile, blue light causes photochemical damage to the retina, and may be associated with age-related macular degeneration (AMD). At present, clear intraocular lenses (IOLs) and blue-blocking IOLs are both widely used for cataract surgery; there is currently a lack of randomised controlled trials to determine whether clear or blue-blocking IOLs should be used.

METHODS AND ANALYSIS

This randomised controlled trial will recruit 1000 cataract patients and randomly allocate them to receive clear IOLs or blue-blocking IOLs in a ratio of 1:1. The primary outcomes are mortality and the incidence of cardiovascular disease, cancer and AMD. Secondary outcomes are fasting plasma glucose, triglycerides, cholesterol, glycated haemoglobin, sleep quality, daytime sleepiness depressive symptoms, light sensitivity, the circadian rhythm of physical activity, wrist skin temperature and urinary melatonin metabolite. Primary outcomes will be followed until 20 years after surgery, and secondary outcomes will be assessed at baseline and 1 year after surgery.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the Institutional Review Board of Nara Medical University (No. 13-032). The findings of this study will be communicated to healthcare professionals, participants and the public through peer-reviewed publications, scientific conferences and the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) home page.

TRIAL REGISTRATION NUMBER

UMIN000014680.

Color of intra-ocular lens and cataract type are prognostic determinants of health indices after visual and photoreceptive restoration by surgery

Background: This study compared post-operative quality of life and sleep according to the type of cataract opacity and color of the implanted intra-ocular lens (IOL).

Methods: This is a cohort study and participants were 206 patients (average age 74.1 years) undergoing cataract surgery with the implantation of a clear ultra-violet (UV)-blocking IOL (C) or a yellow blue-light-blocking IOL (Y). Participants were evaluated using the National Eye Institute Visual Function Questionnaire (VFQ-25) and Pittsburgh Sleep Quality Index (PSQI) before surgery and 2 and 7 months after surgery. Changes in sub-scale scores of VFQ-25 and PSQI were compared.

Results: Sub-scale analyses for improvement after surgery revealed significant differences in ocular pain scores on the VFQ-25 (Y>C; the higher the score, the better the outcome). Furthermore, there were significant differences between the two IOLs in terms of the sleep latency score (C>Y) and sleep disturbances score (C>Y). A posterior sub-capsular cataract was significantly correlated with improvements in ocular pain and sleep latency scores. These effects were successfully represented by the change in scores rather than absolute post-operative scores because individual standard of response may often change after intervention, recognized as a response shift phenomenon in patient-reported outcome study. Regarding seasonal differences, patients who had surgery in summer exhibited relatively better sleep quality than those who had surgery in winter.

Conclusions: Analysis of sub-scales of health indices demonstrated characteristic prognoses for each IOL and cataract type. Cataract surgery may potentially contribute to systemic health in older adults.

Unilateral persistent hyperplastic primary vitreous: intensive management approach with excellent outcome beyond visual maturation

Persistent hyperplastic primary vitreous (PHPV) is an ocular developmental disorder resulting from incomplete apoptosis of the embryonic hyaloid vasculature. Unilateral PHPV is traditionally associated with a poor prognosis because of the challenges associated with managing progressive anisometropic amblyopia. We report a child with unilateral PHPV who underwent cataract extraction, primary posterior capsulotomy with anterior vitrectomy and intraocular lens implantation followed by combined trabeculectomy/trabeculotomy within the first 8 weeks of life. Intensive optometric and orthoptic input was required for many years to manage the increasing anisometropic amblyopia with final visual acuity of 20/40 unaided in the affected eye and without evidence of glaucomatous optic neuropathy. This case illustrates the excellent visual outcome possible in a child with complex, unilateral PHPV using an intensive management approach comprising: early surgical intervention for congenital cataract and secondary glaucoma, meticulous monitoring of refraction, visual acuity and intraocular pressure and motivated parents who engaged in the management.

Short-term influence of cataract surgery on circadian biological rhythm and related health outcomes (CLOCK-IOL trial): study protocol for a randomized controlled trial

Background

Light information is the most important cue of circadian rhythm which synchronizes biological rhythm with external environment. Circadian misalignment of biological rhythm and external environment is associated with increased risk of depression, insomnia, obesity, diabetes, cardiovascular disease, and cancer.

Increased light transmission by cataract surgery may improve circadian misalignment and related health outcomes. Although some observational studies have shown improvement of depression and insomnia after cataract surgery, randomized controlled trials are lacking. We will conduct a parallel-group, assessor-blinded, simple randomized controlled study comparing a cataract surgery group at three months after surgery with a control group to determine whether cataract surgery improves depressive symptoms, sleep quality, body mass regulation, and glucose and lipid metabolism.

Methods/Design

We will recruit patients who are aged 60 years and over, scheduled to receive their first cataract surgery, and have grade 2 or higher nuclear opacification as defined by the lens opacities classification system III. Exclusion criteria will be patients with major depression, severe corneal opacity, severe glaucoma, vitreous haemorrhage, proliferative diabetic retinopathy, macular oedema, age-related macular degeneration, and patients needing immediate or combined cataract surgery. After baseline participants will be randomized to two groups. Outcomes will be measured at three months after surgery among the intervention group, and three months after baseline among the control group. We will assess depressive symptoms as a primary outcome, using the short version geriatric depression scale (GDS-15). Secondary outcomes will be subjective and actigraph-measured sleep quality, sleepiness, glycated haemoglobin, fasting plasma glucose and triglyceride, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, body mass index, abdominal circumference, circadian rhythms of physical activity and wrist skin temperature, and urinary melatonin metabolite. Chronotype and visual function will be assessed using the ‘morningness-eveningness’ questionnaire, the Munich chronotype questionnaire, and the National Eye Institute Visual Function Questionnaire.

Discussion

Although there are potential limitations due to the difference in duration from baseline survey to outcome measurements between two groups, any seasonal effect on the outcome measurement will be balanced as a result of continuous inclusion of participants through the year, and outcomes will be adjusted for day length at outcome measurements at analysis.

Trial registration

UMIN000014559, UMIN Clinical Trials Registry, registered on 15 July 2014.