Multidimensional sleep health and diabetic retinopathy: Systematic review and meta-analysis

Diabetic retinopathy (DR) is one of the most prevalent microvascular diabetic complications. Poor sleep health and obstructive sleep apnea (OSA) are risk factors for diabetes and poor glycemic control. Recent studies have suggested associations between poor sleep health/OSA and DR. Furthermore, there have been suggestions of melatonin dysregulation in the context of DR. We conducted a systematic review and meta-analysis exploring the associations between multidimensional sleep health (duration, satisfaction, efficiency, timing/regularity and alertness), OSA and melatonin with DR. Forty-two studies were included. Long, but not short sleep, was significantly associated with DR, OR 1.41 (95%CI 1.21, 1.64). Poor sleep satisfaction was also significantly associated with DR, OR 2.04 (1.41, 2.94). Sleep efficiency and alertness were not associated with DR, while the evidence on timing/regularity was scant. Having OSA was significantly associated with having DR, OR 1.34 (1.07, 1.69). Further, those with DR had significantly lower melatonin/melatonin metabolite levels than those without DR, standardized mean difference -0.94 (-1.44, -0.44). We explored whether treating OSA with continuous positive airway pressure (CPAP) led to improvement in DR (five studies). The results were mixed among studies, but potential benefits were observed in some. This review highlights the association between poor multidimensional sleep health and DR.

Continuous Positive Airway Pressure Effect on Progression of Retinal Disease in Patients with Sleep Apnea and Nonproliferative Diabetic Retinopathy: A Randomized Clinical Trial

Rationale: Obstructive sleep apnea (OSA) is associated with impaired glycemic control and a higher risk of vascular complications, such as diabetic retinopathy. However, the effect of apnea-hypopnea suppression on retinal disease progression is unclear. Objectives: To evaluate the efficacy and safety of continuous positive airway pressure (CPAP) for the reduction of retinal lesions in patients with non-proliferative diabetic retinopathy (NPDR) and OSA. Methods: This open-label, parallel-group, randomized controlled trial was conducted between October 2016 and February 2020 at a university hospital in Spain. The date of final follow-up was March 2, 2021. Eighty-three patients with OSA and mild to moderate NPDR receiving stable treatment were randomized to receive CPAP and usual care (43 patients with 79 available eyes) or usual care alone (40 patients with 67 available eyes) for 52 weeks. The primary outcomes were the change in the percentage of eyes with retinal exudates and the number of retinal microhemorrhages from baseline to week 52. We also assessed the effects of both interventions on retinal thickness by means of optical coherence tomography, serum concentrations of glycated hemoglobin, blood pressure, lipid concentrations, sleepiness, and quality of life. Results: Fifty-two weeks of CPAP treatment was associated with reductions from baseline in the percentage of eyes with hard exudates (overall difference, -21.7%; P = 0.035) and in optical coherence tomography indices of retinal edema, including central subfield thickness and cube volume. However, in patients who met prespecified criteria for CPAP adherence, treatment was also associated with a higher number of retinal microhemorrhages at 52 weeks (intergroup adjusted difference, 6.0 [95% confidence interval, 0.6-11.5]; P = 0.029), which was directly related to prescribed pressure levels. CPAP treatment also improved glycemic control, sleepiness, and general health-related quality of life. Conclusions: In patients with OSA and NPDR, long-term CPAP treatment in addition to usual care may result in slower progression of retinal disease, although it could also induce an increase in retinal microhemorrhages. Clinical trial registered with www.clinicaltrials.gov (NCT02874313).

Diabetic Macular Oedema Guidelines: An Australian Perspective

The number of people living with diabetes is expected to rise to 578 million by 2030 and to 700 million by 2045, exacting a severe socioeconomic burden on healthcare systems around the globe. This is also reflected in the increasing numbers of people with ocular complications of diabetes (namely, diabetic macular oedema (DMO) and diabetic retinopathy (DR)). In one study examining the global prevalence of DR, 35% of people with diabetes had some form of DR, 7% had PDR, 7% had DMO, and 10% were affected by these vision-threatening stages. In many regions of the world (Australia included), DR is one of the top three leading causes of vision loss amongst working age adults (20-74 years). In the management of DMO, the landmark ETDRS study demonstrated that moderate visual loss, defined as doubling of the visual angle, can be reduced by 50% or more by focal/grid laser photocoagulation. However, over the last 20 years, antivascular endothelial growth factor (VEGF) and corticosteroid therapies have emerged as alternative options for the management of DMO and provided patients with choices that have higher chances of improving vision than laser alone. In Australia, since the 2008 NHMRC guidelines, there have been significant developments in both the treatment options and treatment schedules for DMO. This working group was therefore assembled to review and address the current management options available in Australia.

Optical coherence tomography angiography and Humphrey visual field in patients with obstructive sleep apnea

STUDY OBJECTIVES

To determine if obstructive sleep apnea syndrome (OSAS) predisposes patients to glaucoma and macular disease due to vascular compromise by evaluating retinal and optic nerve vasculature and function using optical coherence tomography angiography and Humphrey visual field testing, respectively.

METHODS

In this prospective, observational, cross-sectional study 45 patients undergoing polysomnography ordered per standard of care were selected and stratified based on apnea-hypopnea index (AHI). Medical history, visual acuity testing, 24-2 Humphrey visual field, intraocular pressure measurement, and optical coherence tomography angiography studies of the macular and peripapillary retina were obtained. Correlations between polysomnography parameters and imaging data were analyzed.

RESULTS

The radial peripapillary capillary vascular density demonstrated no relationship to AHI (95% confidence interval [CI] [-0.026,0.038]) or severity of OSAS (95% CI: [-0.772, 3.648]) for moderate OSAS compared to mild/normal and (-1.295, 3.1421) for severe compared to mild/normal. Optical coherence tomography angiography superficial parafoveal vascular density (95% CI: [-0.068,0.011], deep parafoveal vascular density (95% CI: [-0.080,0.009]), and foveal avascular zone (95% CI: [-0.001, 0.001]) showed no statistically significant relationship to AHI or OSAS severity after controlling for confounders. Optical coherence tomography retinal nerve fiber layer thickness increased with AHI (P = .014), but there was no statistically significant correlation with OSAS severity with retinal nerve fiber layer thickness (95% CI: [-12.543, 6.792] for moderate comparing to normal and [-2.883, 16.551] for severe comparing to normal). Visual field parameters were unaffected by OSAS (95% CI: mean deviation [-0.21,0.29], pattern standard deviation: [-0.351, 0.121], visual field index: [-0.166, 0.329]). Optical coherence tomography choroidal thickness showed a statistically significant decrease when OSAS was grouped by severity (P = .0092) but did not correlate with AHI (P = .129, 95% CI: [-1.210, 0.095]).

CONCLUSIONS

The severity of OSAS did not show a statistically significant effect on parameters associated with glaucoma or macular vascular disease. Larger cohorts may be required to determine the physiologic consequences of OSAS on the macular and optic nerve vasculature, structure, and function.

CITATION

Davanian A, Williamson L, Taylor C, et al. Optical coherence tomography angiography and Humphrey visual field in patients with obstructive sleep apnea. J Clin Sleep Med 2022;18(9):2133-2142.

Examining the Relationship Between Diabetic Macular Edema, and Obstructive Sleep Apnea

Purpose

This prospective cohort study examined the relationship between diabetic macular edema (DME), diabetic retinopathy (DR) and obstructive sleep apnea (OSA) in patients after 1 year of treatment with anti-VEGF injection and/or continuous positive airway pressure (CPAP).

Patients and Methods

The study included adults with type 1 or 2 diabetes mellitus with diabetic retinopathy. Polysomnography metrics were measured at baseline. Ophthalmologic metrics were measured at baseline, six-month (6m) and twelve-month (12m) follow-up. All DME+ patients received standard care, and all OSA+ patients were advised continuous positive airway pressure (CPAP). Logistic regression between DR severity and OSA severity was performed. Analysis of variance (ANOVA) was performed between subgroups.

Results

Seventy-four eyes of 49 patients with DR were included. Prevalence of OSA was significantly higher in the DME+ group (70.7%) than DME- group (42.4%, p < 0.05). A significantly lower average minimum SaO₂ was noted in OSA+DME+ (81.74%) than OSA+DME- eyes (88.23%, p < 0.05). Logistic regression analysis of ophthalmological and sleep metrics showed no correlation between DR and OSA severity. CPAP adherence was 20% (6/30) in the OSA+DME+ cohort and 36% (5/14) in the OSA+DME- cohort. At 12m, CPAP-adherent OSA+DME+ showed significantly lower DR severity score (1.00 ± 0.0) than CPAP non-adherent OSA+DME+ (1.36 ± 0.80, p = 0.042). No significant patterns were noted for visual acuity and mean central retinal thickness.

Conclusion

DME is associated with the presence of OSA. Minimum SaO₂ is a significant OSA clinical variable for DME. DR severity is not associated with OSA severity. CPAP coupled with intravitreal anti-VEGF therapy may be helpful for reducing DR severity in DME+ eyes. Presence of OSA may diminish intravitreal anti-VEGF efficacy on anatomical (mean CRT) and functional (VA) outcomes of DME.

Sleep apnea and eye diseases: evidence of association and potential pathogenic mechanisms

Eye diseases are an important group of increasingly prevalent disorders that contribute very significantly to disability and represent a considerable health burden. Some data suggest that several of these diseases may be associated with sleep-disordered breathing, mainly obstructive sleep apnea (OSA), due to intermediate mechanisms, such as intermittent hypoxia or sleep fragmentation. The aims of this systematic review were to identify and critically evaluate the current evidence supporting the existence of a possible relationship between OSA and the more relevant eye diseases as well as to evaluate the potential pathogenic mechanisms. There is a body of largely low-level evidence for the association of OSA with glaucoma, nonarteritic ischemic optic neuropathy, central serous chorioretinopathy, and diabetic retinopathy. Meta-analysis of available case-control studies shows that OSA increases the risk of glaucoma (pooled odds ratio: 1.50; 95% confidence interval: 1.25 to 1.80; P < .001), nonarteritic ischemic optic neuropathy (3.62; 1.94 to 6.76; P < .001), and diabetic retinopathy (1.57; 1.09 to 2.27; P = .02). Moreover, several pathogenic pathways have been identified, mainly related to hypoxic damage, mechanical stress, systemic inflammation, oxidative stress, sympathetic tone, and endothelial dysfunction. In contrast, information about the effect of apnea-hypopnea suppression on the development and progression of eye damage is either nonexistent or of a very low level of evidence. In conclusion, OSA has emerged as an additional potential risk factor for many eye diseases, although their link is weak and contradictory, so further examination is required.

CITATION

García-Sánchez A, Villalaín I, Asencio M, García J, García-Rio F. Sleep apnea and eye diseases: evidence of association and potential pathogenic mechanisms. J Clin Sleep Med. 2022;18(1):265-278.

Obstructive Sleep Apnoea, Other Sleep Parameters and Diabetic Retinopathy

PURPOSE OF REVIEW

To summarise the association between obstructive sleep apnoea and diabetic retinopathy and diabetic macular oedema. To examine the effects of other sleep parameters on diabetic retinopathy and diabetic macular oedema. To discuss the pathophysiology of diabetic eye changes and how it is related to obstructive sleep apnoea.

RECENT FINDINGS

Conflicting data exists in terms of the association of diabetic eye changes with sleep apnoea and/or other sleep parameters. Various cross-sectional studies show PDR to be associated with the prevalence of OSA. Patients who underwent continuous positive airway pressure (CPAP) treatment were significantly less likely to develop pre/proliferative DR. Secondary sleep parameters generally are not associated with DR except for long duration of sleep. Differences in reporting could be due to the different thresholds set to define OSA/ODI and severity of DR/DME, in addition to factors used in multivariate analysis. There is a need for further studies with long-term follow-up and to assess the impact of CPAP on the development and progression of diabetic eye change(s).

Obstructive sleep apnea and the retina: a review

CITATION

This review's objective was to synthesize the literature on the repercussions of obstructive sleep apnea (OSA) in the retinal vascular system. Two independent investigators conducted a search using the MEDLINE/PubMed database using the following terms: sleep apnea syndrome, obstructive sleep apnea, retina, vascular tortuosity, central serous chorioretinopathy, diabetes mellitus, and subfoveal choroidal thickness. Patients with OSA present increased vascular tortuosity compared with patients without OSA, decreased parafoveal and peripapillary vessel density, and increased retinal vein occlusion incidence. In central serous chorioretinopathy patients and patients who are poor responders to intravitreal anti-VEGF (-vascular endothelial growth factor) treatment for macular edema, OSA is more frequent. Macular choroidal thickness alterations are controversial, and OSA may worsen diabetic maculopathy, thus being a risk factor for diabetic retinopathy, proliferative diabetic retinopathy, and macular edema. OSA is a prevalent syndrome with many systemic vascular changes. The retina and choroid are the most affected ocular structures, with primarily vascular changes. New noninvasive technologies such as optical coherence tomography and optical coherence tomography angiography could help to better understand retinal structures and help clarify the ophthalmological repercussions of OSA.

CITATION

Nakayama LF, Tempaku PF, Bergamo VC, et al. Obstructive sleep apnea and the retina: a review. J Clin Sleep Med. 2021;17(9):1947-1952.

Ocular Complications of Obstructive Sleep Apnea

Obstructive sleep apnea (OSA), the most common form of sleep-disordered breathing, is characterized by repetitive episodes of paused breathing during sleep, which in turn induces transient nocturnal hypoxia and hypercapnia. The high prevalence of OSA and its associated health consequences place a heavy burden on the healthcare system. In particular, the consequent episodic oxygenic desaturation/reoxygenation series and arousals from sleep in patients with OSA have the potential to trigger oxidative stress, elevated systemic inflammatory responses, and autonomic dysfunction with sympathetic activation. Given these adverse side-effects, OSA is highly correlated to many eye diseases that are common in everyday ophthalmic practices. Some of these ocular consequences are reversible, but they may permanently threaten a patient’s vision if not treated appropriately. Here, this article seeks to review the ocular consequences and potential pathophysiologic associations in patients with OSA. Understanding these OSA-related eye diseases may help clinicians provide comprehensive care to their patients.

The Associations of Obstructive Sleep Apnea and Eye Disorders: Potential Insights into Pathogenesis and Treatment

Purpose of Review

Obstructive sleep apnea (OSA) patients are at significantly increased risks for cardiovascular and cerebrovascular morbidities. Recently, there has been heightened interest in the association of OSA with numerous ocular diseases and possible improvement of these conditions with the initiation of OSA treatment. We reviewed the current evidence with an emphasis on the overlapping pathogeneses of both diseases.

Recent Findings

Currently available literature points to a substantial association of OSA with ocular diseases, ranging from those involving the eyelid to optic neuropathies and retinal vascular diseases. Since the retina is one of the highest oxygen-consuming tissues in the body, the intermittent hypoxia and hypercapnia ensuing in OSA can have deleterious effects on ocular function and health. Tissue hypoxia, autonomic dysfunction, microvascular dysfunction, and inflammation all play important roles in the pathogenesis of both OSA and ocular diseases. Whether OSA treatment is capable of reversing the course of associated ocular diseases remains to be determined. It is anticipated that future therapeutic approaches will target the common underlying pathophysiologic mechanisms and promote favorable effects on the treatment of known associated ocular diseases.

Summary

Emerging evidence supports the association of ocular diseases with untreated OSA. Future studies focusing on whether therapeutic approaches targeting the common pathophysiologic mechanisms will be beneficial for the course of both diseases are warranted.

Diabetic retinopathy and diabetic macular oedema pathways and management: UK Consensus Working Group

The management of diabetic retinopathy (DR) has evolved considerably over the past decade, with the availability of new technologies (diagnostic and therapeutic). As such, the existing Royal College of Ophthalmologists DR Guidelines (2013) are outdated, and to the best of our knowledge are not under revision at present. Furthermore, there are no other UK guidelines covering all available treatments, and there seems to be significant variation around the UK in the management of diabetic macular oedema (DMO). This manuscript provides a summary of reviews the pathogenesis of DR and DMO, including role of vascular endothelial growth factor (VEGF) and non-VEGF cytokines, clinical grading/classification of DMO vis a vis current terminology (of centre-involving [CI-DMO], or non-centre involving [nCI-DMO], systemic risks and their management). The excellent UK DR Screening (DRS) service has continued to evolve and remains world-leading. However, challenges remain, as there are significant variations in equipment used, and reproducible standards of DMO screening nationally. The interphase between DRS and the hospital eye service can only be strengthened with further improvements. The role of modern technology including optical coherence tomography (OCT) and wide-field imaging, and working practices including virtual clinics and their potential in increasing clinic capacity and improving patient experiences and outcomes are discussed. Similarly, potential roles of home monitoring in diabetic eyes in the future are explored. The role of pharmacological (intravitreal injections [IVT] of anti-VEGFs and steroids) and laser therapies are summarised. Generally, IVT anti-VEGF are offered as first line pharmacologic therapy. As requirements of diabetic patients in particular patient groups may vary, including pregnant women, children, and persons with learning difficulties, it is important that DR management is personalised in such particular patient groups. First choice therapy needs to be individualised in these cases and may be intravitreal steroids rather than the standard choice of anti-VEGF agents. Some of these, but not all, are discussed in this document.

Association Between Obstructive Sleep Apnea and Diabetic Macular Edema in Patients with Type 2 Diabetes

PURPOSE

To evaluate the relationship between obstructive sleep apnea (OSA) and diabetic macular edema (DME) and the effect of OSA on refractory DME in patients with type 2 diabetes (T2DM).

DESIGN

Retrospective clinical cohort study.

METHODS

A population-based study was conducted at Chang Gung Memorial Hospital from March 1, 2009, to March 1, 2020. Among 14,152 patients who had undergone polysomnography (PSG) and whose data were registered on the sleep center's PSG database, 121 patients (242 eyes) with T2DM were enrolled according to the International Classification of Diseases, Ninth Revision (ICD-9) code 3620 for diabetic retinopathy (DR). Patients with a secondary cause of macular edema and those lacking medical records were excluded. All patients with T2DM enrolled in our study received both optical coherence tomography (OCT) and PSG. The prevalence of severe (apnea-hypopnea index [AHI] ≥30) and nonsevere (AHI <30) OSA was compared between patients with and without DME and refractory DME.

RESULTS

In total, 102 eyes (54 patients) were divided into groups of 40 eyes with DME or 62 eyes without DME. Severe OSA (odds ratio, 7.36; 95% confidence interval [CI]: 1.32-40.96; P = .023) was significantly associated with DME. Refractory DME was significantly more frequent in patients with severe OSA (27%) than in those with nonsevere OSA (0%; P = .009). Cox proportional hazards regression analysis revealed that OSA (hazard ratio, 2.97; CI, 1.08-8.16; P = .034) independently increased the DME risk after adjustment for age, sex, glycohemoglobin level, hypertension, and hypercholesterolemia.

CONCLUSIONS

Severe OSA is a risk factor for DME and is associated with having refractory DME.

The Veterans Affairs Continuous Positive Airway Pressure Use and Diabetic Retinopathy Study

SIGNIFICANCE

Obstructive sleep apnea has been linked to the development and progression of diabetic retinopathy. In this study, diabetic patients compliant with continuous positive airway pressure therapy (CPAP) for sleep apnea were less likely to have retinopathy, emphasizing the benefits and potential therapeutic role of CPAP in individuals with both conditions.

PURPOSE

The aim of this study was to compare the prevalence of diabetic retinopathy in type 2 diabetic patients with obstructive sleep apnea who were compliant with CPAP therapy with those who were not compliant with CPAP therapy.

METHODS

A retrospective cross-sectional review of type 2 diabetic patients using CPAP for obstructive sleep apnea was conducted. The prevalence of retinopathy was identified, and groups with and without retinopathy were compared using univariate analyses and multivariate logistic regression.

RESULTS

The prevalence of retinopathy was 19.6% (n = 321). Retinopathy was significantly less prevalent in those compliant with CPAP (odds ratio, 0.54; 95% confidence interval, 0.31 to 0.94; P = .04). The relationship remained statistically significant when adjusting for other factors known to impact the course of diabetic eye disease.

CONCLUSIONS

Increased CPAP compliance may mitigate the risk of developing diabetic retinopathy in type 2 diabetic patients with obstructive sleep apnea.

Effects of CPAP for patients with OSA on visual sensitivity and retinal thickness

OBJECTIVE

Obstructive sleep apnea/hypopnea syndrome (OSA) could compromise oxygenation of the optic nerve and cause glaucomatous optic neuropathy; there has been no study to investigate the microstructure changes of the optic nerve and retina in OSA patients before and after continuous positive airway pressure (CPAP) therapy. In this study, we assess whether treatment with CPAP might improve visual sensitivity and retinal thickness in patients with OSA.

METHODS

Patients with OSA were prospectively recruited and referred for ophthalmologic evaluation at baseline and three months after CPAP treatment. Each patient underwent an ophthalmological exam, standard automated perimetry (SAP), and optical coherence tomography (OCT) exam. Peripapillary retinal nerve fiber layer (RNFL) and macular layer (ML) thickness parameters were measured. The SAP, RNFL, and ML thickness parameters before and after treatment were compared.

RESULTS

A total of 32 OSA patients were consecutively enrolled. At baseline, the mean deviation (MD) of SAP was -2.15 ± 1.90 dB (dB). After CPAP treatment, the MD was -1.38 ± 1.37 dB (p = 0.017). Regarding the OCT parameters, the inferior quadrant and nasal-inferior sector of RNFL thickness significantly improved after treatment (p = 0.025 and 0.004, respectively). The ML thickness in the superior-inner sector, inferior-outer sector, nasal-outer sector, superior hemisphere, and inferior hemisphere were also significantly improved after treatment. Improvement of ML thickness in the superior-inner sector positively correlated with the apnea/hypopnea index (r = 0.405, p = 0.022) and desaturation index (r = 0.473, p = 0.006) on pre-treatment polysomnography.

CONCLUSION

The treatment of CPAP could improve visual sensitivity and increase retinal thickness in patients with OSA.

Elevated obstructive sleep apnoea risk score is associated with poor healing of diabetic foot ulcers: a prospective cohort study

AIMS

To assess the prevalence of risk factors for obstructive sleep apnoea in people with diabetic foot ulcers and to determine whether this risk predicts diabetic foot ulcer healing.

METHODS

We studied 94 consecutive people (69% men) with diabetic foot ulcers (Type 2 diabetes, n=66, Type 1 diabetes, n=28) attending a university hospital foot unit. All participants were screened for obstructive sleep apnoea using the STOP-BANG questionnaire, with a score ≥4 identifying high risk of obstructive sleep apnoea. The primary outcome was poor diabetic foot ulcer healing, defined as diabetic foot ulcer recurrence (diabetic foot ulcers which healed and re-ulcerated in same anatomical position) and/or diabetic foot ulcer persistence (no evidence of healing on clinical examination). All participants were evaluated at 12 months.

RESULTS

Of the 94 participants, 60 (64%) had a STOP-BANG score ≥4. Over 12 months, 27 participants with a score ≥4 had poor diabetic foot ulcer healing as compared to seven with a score <4 (45% vs 20.5%; P=0.025). A STOP-BANG score ≥4 significantly increased the relative risk of poor healing more than twofold, independently of other risk factors in multivariable analyses.

CONCLUSIONS

There is a high prevalence of features and risk of obstructive sleep apnoea in people with diabetic foot ulcers. A STOP-BANG score ≥4 predicts poor diabetic foot ulcer healing. Obstructive sleep apnoea may be a potential, modifiable risk factor/treatment target to improve diabetic foot ulcer outcomes.

Continuous positive airway pressure effect on visual acuity in patients with type 2 diabetes and obstructive sleep apnoea: a multicentre randomised controlled trial

We sought to establish whether continuous positive airway pressure (CPAP) for obstructive sleep apnoea (OSA) in people with type 2 diabetes and diabetic macular oedema (DMO) improved visual acuity.We randomly assigned 131 eligible patients aged 30-85 years from 23 UK centres with significant DMO causing visual impairment (LogMAR letters identified ≥39 and ≤78, score 0.92-0.14) plus severe OSA on screening to either usual ophthalmology care (n=67) or usual ophthalmology care plus CPAP (n=64) for 12 months.Mean age of participants was 64 years, 73% male, mean body mass index 35.0 kg·m- 2 Mean 4% oxygen desaturation index was 36 events·h-1 There was no significant difference in the visual acuity at 12 months between the CPAP group and the control group (mean LogMAR 0.33 (95% CI 0.29-0.37) versus 0.31 (95% CI 0.27-0.35); p=0.39), and no significant correlation between change in LogMAR and average CPAP use. The median±sd (range) daily CPAP use was 3.33±2.25 (0-7.93) h at 3 months, 3.19±2.54 (0-8.07) h at 6 months and 3.21±2.70 (0-7.98) h at 12 months.CPAP therapy for OSA did not improve visual acuity in people with type 2 diabetes and DMO compared with usual care alone over 12 months.

The Epidemiology of Sleep and Diabetes

PURPOSE OF REVIEW

To provide an overview of the mechanistic and epidemiologic evidence linking sleep-related exposures, such as short sleep duration, obstructive sleep apnea, shift work, and insomnia, with type 2 diabetes risk in adults.

RECENT FINDINGS

Both poor sleep habits and sleep disorders are highly prevalent among adults with type 2 diabetes. In observational studies, short sleep duration, obstructive sleep apnea, shift work, and insomnia are all associated with higher risk of incident type 2 diabetes and may predict worse outcomes in those with existing diabetes. However, interventional studies addressing sleep abnormalities in populations with or at high risk for type 2 diabetes are scarce. Although common sleep abnormalities are associated with risk of incident type 2 diabetes and worse prognosis in those with established diabetes, there are few randomized trials evaluating the impact of sleep-focused interventions on diabetes, making it difficult to determine whether the relationship is causal.

Obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is increasing in prevalence due to rising obesity. While OSA is a disorder primarily of the upper airway during sleep, its pathophysiological impact on other body systems is increasingly recognised. There has been interest in the prevalence of OSA in different ophthalmic conditions and possible causation has been postulated. As OSA is common, it can be expected that people with co-existent OSA will be found in any ophthalmic disease population studied. To determine with confidence the significance of finding patients with OSA in a particular cohort requires a well matched control group, ideally matched for age, obesity, gender and co-morbidities. Only if one can say with certainty that the prevalence of OSA is higher in a group with a particular co-existent ophthalmic disease can we begin to speculate about possible mechanisms for the overlap in these conditions. Possible mechanisms for how OSA might affect the eye are discussed in this review. The current literature is reviewed with respect to diabetic retinopathy, glaucoma, floppy eyelid syndrome, non-arteritic ischaemic optic neuropathy, keratoconus and AMD. Associations with OSA have been found, but robust prospective studies using multi-channel sleep studies to diagnose OSA are lacking. Gaps remain in the evidence and in our knowledge. It is hoped that this review will highlight the need for ophthalmologists to consider OSA in their patients. It also makes recommendations for future research, especially to consider whether therapies for OSA can also be effective for ophthalmic disorders.

The Clinical Impact of Systematic Screening for Obstructive Sleep Apnea in a Type 2 Diabetes Population-Adherence to the Screening-Diagnostic Process and the Acceptance and Adherence to the CPAP Therapy Compared to Regular Sleep Clinic Patients

Obstructive sleep apnea (OSA) is a common disorder in Type 2 diabetes (T2D) patients further increasing their already high cardiovascular risk. As T2D patients typically not report OSA symptoms, systematic screening for OSA in this population is warranted. We aimed to determine the readiness of T2D patients to undergo screening and to compare their adherence to continuous positive airway pressure (CPAP) therapy with "regular" sleep clinic patients who typically seek medical advice on their own initiative. We therefore recruited 494 consecutive T2D patients and offered them OSA screening using home sleep monitoring (type IV device). All participants in high risk of moderate-to-severe OSA were recommended home sleep apnea testing (HSAT) followed by CPAP therapy. Patients were followed-up for 12 months and outcomes compared to 228 consecutive sleep clinic patients undergoing HSAT. Among 307 screened T2D patients, 94 (31%) were identified at high risk of moderate-to-severe OSA. Subsequently, 54 patients underwent HSAT, 51 were recommended, and 38 patients initiated CPAP (acceptance 75%). Among 228 sleep clinic patients, 92 (40%) were recommended and 74 patients initiated CPAP (acceptance 80%). After 1 year, 15 (39%) T2D and 29 (39%) sleep clinic patients showed good CPAP adherence (use ≥ 4 h/night ≥ 70% nights). In conclusion, 20 T2D patients needed to be screened in order to obtain one successfully treated patient. OSA screening in T2D patients identified 31% with moderate-to-severe OSA. Once diagnosed, their CPAP acceptance and adherence did not differ from sleep clinic patients. However, the reasons for the high dropout during the screening-diagnostic process impacting the overall success of the screening program need to be identified and addressed.

Obstructive sleep apnoea in diabetes: Does it matter?

Obstructive sleep apnoea (OSA) is very common in patients with Type 2 diabetes (T2D), which is not surprising considering that obesity is a common risk factor for both conditions. In general population studies, OSA has been shown to be associated with several comorbidities including increased risk of road traffic accidents, T2D, hypertension and lack of nocturnal dipping of blood pressure, hyperlipidaemia, increased inflammation, increased risk of cardiovascular disease and mortality, increased risk of atrial fibrillation, worse quality of life, and erectile dysfunction. However, the impact of OSA on diabetes-related vascular and metabolic outcomes remains unclear. Furthermore, the impact of continuous positive airway pressure (CPAP) treatment in patients with T2D is also unclear. This unclarity regarding the impact of OSA and CPAP in patients with T2D has possibly contributed to the lack of screening for OSA in patients with T2D in the UK despite the high prevalence of OSA in patients with T2D. In this commentary, I provide an overview about OSA with a particular focus on its role and impact in patients with T2D.

Diabetic macular oedema

Diabetic macular oedema, characterised by exudative fluid accumulation in the macula, is the most common form of sight-threatening retinopathy in people with diabetes. It affects one in 15 people with diabetes resulting in more than 20 million cases worldwide. Few epidemiological studies have been done to specifically investigate risk factors for diabetic macular oedema, although poor glycaemic and blood pressure control are associated with the presence and development of the disorder. The pathophysiological processes begin with chronic hyperglycaemia, and interplay between vascular endothelial growth factor (VEGF) and inflammatory mediators. Non-invasive imaging using optical coherence tomography has allowed clinicians to detect mild levels of diabetic macular oedema in order to monitor progress and guide treatment. Although focal or grid laser photocoagulation was the traditional mode of treatment, intraocular pharmacotherapy with anti-VEGF agents is now the standard of care. However, these therapies are expensive and resource intensive. Emerging therapeutic strategies include improving efficacy and duration of VEGF suppression, targeting alternative pathways such as inflammation, the kallikrein-kinin system, the angiopoietin-Tie2 system, and neurodegeneration, and using subthreshold and targeted laser therapy. Ongoing research should lead to improvements in screening, diagnosis, and management of diabetic macular oedema.

Effect of obstructive sleep apnoea on diabetic retinopathy and maculopathy: a systematic review and meta-analysis

AIMS

To summarize the association between obstructive sleep apnoea and diabetic retinopathy and diabetic maculopathy, and to examine the effects of oxygen desaturation index, mean and minimum oxygen saturation and time spent with < 90% oxygen saturation on diabetic retinopathy and diabetic maculopathy.

METHODS

A systematic search was performed for papers published from inception to January 2014 in MEDLINE, EMBASE and the Cochrane Database of Systematic Reviews using indexed terms and free text. Additional searches were carried out for grey literature. Two authors conducted the study selection and quality assessment. Data extraction was performed by the main author and checked by the other authors.

RESULTS

One cohort study and 15 cross-sectional studies were included for narrative synthesis and three for meta-analyses. There was no convincing evidence that obstructive sleep apnoea was associated with diabetic retinopathy, although some evidence suggested that obstructive sleep apnoea was associated with greater severity of diabetic retinopathy and advanced diabetic retinopathy in people with Type 2 diabetes. Only six studies examined the impact of obstructive sleep apnoea on diabetic maculopathy and our narrative review suggests there is an association in Type 2 diabetes. Oxygen desaturation index, mean oxygen saturation or time spent with < 90% oxygen saturation were not associated with diabetic retinopathy, and insufficient evidence was available to draw conclusions on their effects on diabetic maculopathy; however, there was evidence from both narrative synthesis and meta-analysis that minimum oxygen saturation had an impact on diabetic retinopathy (pooled odds ratio 0.91, 95% CI 0.87-0.95; I(2) = 0%).

CONCLUSIONS

There is a need for large cohort studies with long-term follow-up data to examine the long-term effects of obstructive sleep apnoea and other sleep variables on advanced retinal disease in diabetes.

Obstructive Sleep Apnoea and Vascular Disease in Patients with Type 2 Diabetes

Obstructive sleep apnoea (OSA) is common and is associated with many vascular risk factors, such as hypertension, insulin resistance, albuminuria, dyslipidaemia, increased inflammation and endothelial dysfunction. Epidemiological studies have shown that OSA is associated with increased cardiovascular disease (CVD) and that continuous positive airway pressure (CPAP) might reduce CVD events in patients with OSA. In addition, OSA has also been shown to be associated with albuminuria, chronic kidney disease, a wide range of ocular diseases and peripheral neuropathy. Considering that CVD and microvascular complications are major contributors to the morbidity, mortality and the economic burden of diabetes and that OSA is common in patients with type 2 diabetes (T2D), it is important to understand the role of OSA in the development and/or progression of vascular disease in patients with T2D and to explore the impact of CPAP on diabetes-related vascular outcomes. The purpose of this article is to review the evidence for the relationship and impact of OSA on vascular disease and vascular risk factors particularly in patients with T2D.

Obstructive sleep apnoea and diabetes: an update

PURPOSE OF REVIEW

The relationship between obstructive sleep apnoea (OSA) and dysglycaemia is well established. However, uncertainty remains as to the extent that obesity mediates this relationship. The impact of OSA treatment on glucose metabolism and the consequences of having OSA in patients with diabetes is unclear. This review aims to summarize the latest evidence regarding the links between OSA and dysglycaemia.

RECENT FINDINGS

OSA is associated with insulin resistance in lean individuals and predicts insulin resistance worsening longitudinally. Continuous positive airway pressure (CPAP) lowers insulin resistance in CPAP-compliant patients. OSA is associated with impaired β-cell function. In patients with type 2 diabetes (T2D), the association between OSA and glycosylated haemoglobin (HbA1c) is related to nocturnal hypoxaemia. Apnoea hypopnoea index (AHI) during rapid eye movement (REM) (not non-REM) sleep is associated with HbA1c. In-laboratory, supervised CPAP improves glycaemia. OSA is associated with and predicts the progression of some diabetic vascular complications. Intensive lifestyle intervention in patients with T2D improves OSA independent of weight loss.

SUMMARY

OSA is associated with insulin resistance and β-cell dysfunction independent of obesity. OSA is associated with HbA1c and vascular complications in patients with T2D. CPAP might improve insulin resistance and glycaemic measures. Lifestyle intervention has a significant impact on AHI in patients with T2D.

Novel insights into metabolic sequelae of obstructive sleep apnoea: a link between hypoxic stress and chronic diabetes complications

An increasing body of evidence suggests that obstructive sleep apnoea (OSA) is independently associated with an increased risk of cardiovascular disease, glucose intolerance, and deteriorations in glycaemic control. Despite the knowledge of a multifactorial pathogenesis of long-term diabetes complications, there is a paucity of information on impact of comorbidities associated with chronic intermittent hypoxemia on development and progression of chronic diabetes complications. This review explores the clinical and scientific overlap of OSA and type 2 diabetes mellitus (T2DM) and its possible impact on the development and progression of diabetes macrovascular and microvascular complications. Multiple prospective observational cohort studies have demonstrated that OSA significantly increases the risk of cardiovascular disease independent of potential confounding risk factors. The current evidence further suggests that OSA with concurrent T2DM is associated with an increased risk of oxidative stress-induced damage of vulnerable endothelial and mesangial cells and peripheral nerves. Further studies are needed to validate the impact of OSA treatment on diabetes micro- and macrovascular complications. Since it is presently still unknown whether OSA treatment may provide a diabetes-modifying intervention that could delay or halt the progression of chronic diabetes complications, the emphasis is on early diagnosis and satisfactory treatment of both OSA and T2DM.

Obstructive Sleep Apnoea and Type 2 Diabetes

With the growing prevalence of obesity, the burden of type 2 diabetes is increasing. Obstructive sleep apnoea (OSA) is a very common medical condition that is associated with increased risk of cardiovascular disease and mortality. Obesity is a common risk factor for OSA and type 2 diabetes and hence it is not surprising that OSA and type 2 diabetes are interlinked. OSA has been shown to be an independent risk factor for the development of incident pre-diabetes/type 2 diabetes. OSA is also associated with worse glycaemic control and vascular disease in patients with type 2 diabetes. However, evidence for the benefits of OSA treatment in patients with type 2 diabetes is still lacking. The aim of this article is to provide an overview of OSA, the relationships between OSA and dysglycaemia and the impact of OSA in patients with type 2 diabetes, highlighting recent advances in the field.

DNA damage in peripheral blood lymphocytes from patients with OSAHS

PURPOSE

Obstructive sleep apnea hypopnea syndrome (OSAHS) is characterized by intermittent hypoxia during sleep time, followed by oxidative stress. Hypoxia-induced oxidative stress can lead to DNA damage, which is related to chromosome aberrations and micronuclei. The purpose of this study is to investigate the level of DNA damage in peripheral blood of patients with OSAHS.

METHODS

Thirty patients with OSAHS diagnosed by polysomnography and 28 healthy volunteers were assessed by the Epworth sleepiness scale. The levels of DNA damage were investigated through the cytokinesis-blocked micronucleus assay.

RESULTS

In the group of patients with OSAHS, the mean frequency of binucleated cells with micronuclei were significantly higher than that in the control group (P<0.01), and the frequency of micronuclei among the patients in mild, moderate, and severe stages differed significantly (P<0.05). The mean frequency of nucleoplasmic bridge in OSAHS group was also higher than that in the control group (P<0.05). Nasal continuous positive airway pressure treatment decreased the frequencies of binucleated cells with micronuclei, nucleoplasmic bridge, and nuclear buds.

CONCLUSIONS

Oxidative DNA damage increased in peripheral blood lymphocytes of OSAHS patients. It may be related to oxidative stress induced by intermittent hypoxia and may be involved in the pathogenesis of cardiovascular and other target organ injuries.

Retinal and choroidal thickness evaluation by SD-OCT in adults with obstructive sleep apnea-hypopnea syndrome (OSAS)

OBJECTIVE

To assess the macular retina and choroidal thickness change in patients with obstructive sleep apnea-hypopnea syndrome (OSAS) with no significant symptoms and pathological changes in the fundus using spectral domain-optical coherence tomography.

METHODS

This prospective, observational case-control study consisted of 53 eyes of 53 patients with OSAS and 12 eyes of 12 age-matched controls. Macular and choroidal thicknesses were measured by optical coherence tomography.

RESULTS

The foveal and nasal macular thicknesses were significantly different between four groups (P=0.001, P=0.016). The foveal thickness of the control group was significantly thinner than that of the severe group (P=0.000). The nasal macular thickness of the control group was significantly thinner than that of the severe group (P=0.008). A significant correlation was found between oxygen desaturation index (ODI) and macular center thickness (r=0.357, R(2)=0.127, P=0.004), with an ODI coefficient of 0.457 (P=0.004). Similarly, a significant correlation was found between ODI and nasal macular thickness (r=0.265, R(2)=0.070, P=0.033), with an ODI coefficient of 0.233 (P=0.033). The subfoveal choroidal thickness was significantly different among the groups (F=3.657, P=0.017). The subfoveal choroidal thickness of the severe group was significantly thinner than that of the control group, mild group, and moderate group (P=0.023, 0.006, and 0.036, respectively). The choroidal thickness 1 mm nasal to the fovea was significantly different between the groups after correcting for age and diopter (F=3.411, P=0.023). The choroidal thickness 1 mm nasal to the fovea was significantly thinner in the severe group compared with the control group and mild group (P=0.013 and 0.010, respectively). Choroidal thickness was significantly correlated with diopter (r=0.520, R(2)=0.270, P<0.001), with a coefficient of 0.327 (P<0.001), and with ODI (r=0.520, R(2)=0.165, P=0.001), with a coefficient of -0.370 (P=0.001).

CONCLUSIONS

OSAS patients showed decreased foveal and nasal macular thickness, similar to the subfoveal and nasal choroidal thickness. These findings suggest that, because of intermittent hypoxia, OSAS might change the retinal and choroidal blood supply.