Obstructive sleep apnoea and increased risk of non-arteritic anterior ischaemic optic neuropathy

Study of nycthemeral variations in blood pressure in patients with non-arteritic anterior ischemic optic neuropathy

PURPOSE

The objective of this study was to analyze the nycthemeral variations in blood pressure (BP) in individuals who presented with non-arteritic anterior ischemic optic neuropathy (NAION).

METHODS

BP was recorded for 24 h (ambulatory blood pressure monitoring, ABPM) in 65 patients with acute NAION. Three definitions of nighttime periods were used: definition 1, 1 a.m.-6 a.m.; definition 2, 10 p.m.-7 a.m.; and definition 3, 10 p.m.-8 a.m. For each of these definitions, patients were classified according to the value of nocturnal reduction in BP into dippers (10-20%), mild dippers (0-10%), reverse dippers (< 0%), and extreme dippers (> 20%).

RESULTS

The proportions of dippers, mild dippers, reverse dippers, and extreme dippers varied significantly depending on the definition chosen. We found the highest number of patients with extreme dipping (23%) when using the strictest definition of nighttime period (definition 1, 1 a.m.-6 a.m.), as compared with 6.2% and 1.5% for the other definitions, respectively. Overall, 13 of 33 patients without known systemic hypertension (39%) were diagnosed with hypertension after ABPM. No risk factor for NAION was associated with the extreme-dipping profile. Finally, the prevalence of systemic hypertension was high (69%).

CONCLUSION

In our population of patients who had an episode of NAION, the proportion of extreme dippers was higher than that usually found in the literature. However, extreme dipping is not a frequent feature of patients with NAION as compared to patients with systemic hypertension. ABPM is recommended for all patients with NAION and unknown history of systemic hypertension.

Peripapillary Retinal Nerve Fiber Layer Thickness as a Predictor of Visual Outcomes in Patients with Acute Nonarteritic Anterior Ischemic Optic Neuropathy

Objective

To evaluate the utility of peripapillary retinal nerve fiber layer thickness (pRNFLT) for the prediction of visual outcomes, including visual acuity (VA) and visual field (VF), in subjects with acute nonarteritic anterior ischemic optic neuropathy (NAION).

Materials and Methods

We performed a retrospective study of data relating to 60 eyes of 60 subjects with acute NAION. Of these, reliable VF values were obtained at both the initial and at 6-month follow-up visits for 30 eyes, which were included in the VF analysis. The pRNFLT was measured globally and separately in all four quadrants (superior, inferior, nasal, and temporal) using optical coherence tomography at the initial visit. Multivariate analysis and the area under the curve (AUC) were used to evaluate the utility of pRNFLT for the prediction of visual outcomes, including favorable VA (VA better than or equal to 20/25) and favorable VF (visual field index (VFI) ≥90%), at the 6-month follow-up visit.

Results

The median VA and mean VFI at the initial visit were 0.40 (interquartile range (IQR): 0.40, 0.54; logarithm of the minimum angle of resolution (logMAR)) and 73.07% ± 6.73%, respectively. The median VA and mean VFI at the 6-month follow-up visit were 0.30 (IQR: 0.00, 0.70) logMAR and 69.27% ± 28.94%, respectively. Thinner temporal-quadrant pRNFLT was associated with favorable VA (odds ratio 0.98; p = 0.042) with a cut-off value of 128 µm (AUC 0.839, 95% CI: 0.732-0.947, sensitivity 77.27%, specificity 84.21%). Thinner nasal-quadrant pRNFLT was associated with favorable VF (odds ratio 0.97; p = 0.047) with a cut-off value of 105 µm (AUC 0.780, 95% CI: 0.612-0.948, sensitivity 90.00%, specificity 70.00%).

Conclusions

The pRNFLT is clinically useful for the prediction of visual outcomes in patients with acute NAION. A temporal-quadrant pRNFLT ≤128 µm and a nasal-quadrant pRNFLT ≤105 µm predict favorable VA and VF at the 6-month follow-up visit, respectively.

Ocular manifestations of obstructive sleep apnea: a systematic review and meta-analysis

BACKGROUND

The association of obstructive sleep apnea (OSA) with development of eye diseases is unclear. This current systematic review and meta-analysis attempts to summarize and analyze associations between OSA and ocular disorders in the literature.

METHODS

PubMed, EMBASE, Google Scholar, Web Of Science, and Scopus databases were searched from 1901 to July 2022 in accordance with the Preferred Reporting in Systematic Review & Meta-Analysis (PRISMA). Our primary outcome assessed the association between OSA and the odds of developing floppy eyelid syndrome (FES), glaucoma, non-arteritic anterior ischemic optic neuropathy (NAION), retinal vein occlusion (RVO), keratoconus (KC), idiopathic intracranial hypertension (IIH), age-related macular degeneration (AMD), and central serous chorioretinopathy (CSR) through odds ratio calculated at the 95% confidence interval.

RESULTS

Forty-nine studies were included for systematic review and meta-analysis. The pooled OR estimate was highest for NAION [3.98 (95% CI 2.38, 6.66)], followed by FES [3.68 (95% CI 2.18, 6.20)], RVO [2.71(95% CI 1.83, 4.00)], CSR [2.28 (95% CI 0.65, 7.97)], KC [1.87 (95% CI 1.16, 2.99)], glaucoma [1.49 (95% CI 1.16, 1.91)], IIH [1.29 (95% CI 0.33, 5.01)], and AMD [0.92 [95% CI 0.24, 3.58] All observed associations were significant (p < 0.001) aside from IIH and AMD.

CONCLUSION

OSA is significantly associated with NAION, FES, RVO, CSR, KC, and glaucoma. Clinicians should be informed of these associations so early recognition, diagnosis, and treatment of eye disorders can be addressed in at-risk groups, and early referral to ophthalmic services is made to prevent vision disturbances. Similarly, ophthalmologists seeing patients with any of these conditions should consider screening and referring patients for assessment of possible OSA.

Non-Arteritic Anterior Ischemic Optic Neuropathy (NA-AION): A Comprehensive Overview

Non-arteritic anterior ischemic optic neuropathy (NA-AION) represents one of the most important causes of blindness or severely impaired vision in middle-aged and elderly people. Unilateral optic disc edema and abrupt, painless vision loss are its defining features. It is commonly assumed that NA-AION is caused by an ischemic infarction of the optic nerve head, and, although the exact pathogenesis is still unknown, several risk factors and comorbidities associated with its development have been found. NA-AION occurs generally in patients older than 50 years who have small optic discs and vasculopathy risk factors. Even though numerous treatment options have been proposed, no available effective medical or surgical therapy or prophylactic measure for NA-AION currently exists. The purpose of present-day therapeutic strategies is therefore to identify and possibly control any underlying modifiable risk factors, aiming to prevent the development of new NA-AION episodes in the affected and fellow eye. A thorough assessment of NAION, including its history, epidemiology, etiology, pathophysiology, risk factors, associated comorbidities, clinical findings, diagnostic tests, treatment choices, prognosis, and future research, is the goal of this work.

Non-Arteritic Anterior Ischemic Optic Neuropathy (NA-AION): A Comprehensive Overview

Non-arteritic anterior ischemic optic neuropathy (NA-AION) represents one of the most important causes of blindness or severely impaired vision in middle-aged and elderly people. Unilateral optic disc edema and abrupt, painless vision loss are its defining features. It is commonly assumed that NA-AION is caused by an ischemic infarction of the optic nerve head, and, although the exact pathogenesis is still unknown, several risk factors and comorbidities associated with its development have been found. NA-AION occurs generally in patients older than 50 years who have small optic discs and vasculopathy risk factors. Even though numerous treatment options have been proposed, no available effective medical or surgical therapy or prophylactic measure for NA-AION currently exists. The purpose of present-day therapeutic strategies is therefore to identify and possibly control any underlying modifiable risk factors, aiming to prevent the development of new NA-AION episodes in the affected and fellow eye. A thorough assessment of NAION, including its history, epidemiology, etiology, pathophysiology, risk factors, associated comorbidities, clinical findings, diagnostic tests, treatment choices, prognosis, and future research, is the goal of this work.

Association Between Vision-Related Functional Burden and Sleep Disorders in Adults Aged 20 and Over in the United States

Purpose

The impact of functional vision, rather than visual acuity, on sleep disorders is not well understood. This study estimated the relationship between vision-related functional burden and sleep disorders among a nationally representative sample in the United States.

Methods

Data from the National Health and Nutrition Examination Survey (NHANES) 2005-2008 were analyzed, which included a total of 10,914 US adults 20 years and older. Sleep disorders and vision-related functional burden were measured by the NHANES questionnaire sleep disorders section and vision section, respectively. Logistic regression was used to explore the association between vision-related functional burden and sleep disorders.

Results

A total of 9384 NHANES participants had complete functional vision and sleep disorders data. The mean age at baseline was 47.8 years, and the weighted prevalence of sleep disorders among adults with vision-related functional burden was 20.3%. After controlling for age, gender, race, smoking status, drinking frequency, general health condition, hypertension, diabetes, coronary heart disease, and depression, vision-related functional burden remained significantly associated with sleep disorders (adjusted odds ratio, 1.502; 95% confidence interval, 1.210-1.864; P < 0.001), whereas the association between presenting visual acuity and sleep disorders was not statistically significant.

Conclusions

Vision-related functional burden rather than impairment of visual acuity was related to the increased prevalence of sleep disorders in adults 20 years and older in the United States.

Translational Relevance

Our study provides insight into the relationship between functional vision and sleep disorders. It should be noted that individuals who report vision-related functional burden might be at risk of sleep disorders.

Non-arteritic anterior ischaemic optic neuropathy and obstructive sleep apnoea

Anterior ischaemic optic neuropathies (AIONs) are a common cause of permanent visual loss in the elderly population. The non-arteritic subtype has been intensively studied. While systemic associations such as hypertension and diabetes mellitus are commonly recognized and treated, others such as obstructive sleep apnoea (OSA) are largely overlooked in daily practice. A 60-year-old man who gave no history of any systemic illness presented to us 1 week following an uneventful cataract surgery with posterior chamber intraocular lens implantation in his right eye. The surgery was performed elsewhere by an eye-healthcare professional where the patient presented primarily with a history of progressively worsening diminution of vision in the same eye for 5 days and was diagnosed with a senile cataract. The postoperative visual gain was unsatisfactory; hence he sought another opinion. A diagnosis of non-arteritic AION (NAION) was established. Systemic evaluation revealed elevated diastolic blood pressure, dyslipidaemia and severe OSA. Prompt treatment with systemic steroids and simultaneous management of the accompanying systemic morbid conditions saved some useful vision in the affected eye. This also prevented involvement of the fellow unaffected eye. A comprehensive ocular examination with emphasis on systemic evaluation of the patient for coexisting illness is imperative before proceeding with any medical or surgical intervention. OSA is a definitive risk factor for the development of NAION, though it remains underdiagnosed and untreated. Cataract surgery has been shown to worsen underlying NAION. Systemic stabilization averts potentially blinding sequel in the unaffected eye of these patients.

Influence of obstructive sleep apnea syndrome on the contralateral optic nerve in patients with unilateral nonarteritic anterior ischemic optic neuropathy

STUDY OBJECTIVES

The aim was to quantitatively evaluate the influence of obstructive sleep apnea syndrome (OSAS) on the morphology and function of the contralateral optic nerve in patients with unilateral nonarteritic anterior ischemic optic neuropathy (NAION).

METHODS

Fifty patients with unilateral NAION were divided into non-OSAS (n = 16), mild OSAS (n = 15), and moderate-severe OSAS (n = 19) groups based on their apnea-hypopnea index (AHI) scores. Systemic and ocular characteristics were compared between these groups. Spearman correlation and multiple linear regression analyses were used to determine the independent factors that most influenced the thickness of the peripapillary retinal nerve fiber layer (pRNFL).

RESULTS

Body mass index and hypertension occurrence were higher in the moderate-severe OSAS group than in the non-OSAS group. Temporal pRNFL was thinner in the moderate-severe group than in the mild and non-OSAS groups, whereas no difference was found between the mild and non-OSAS groups. Spearman correlation showed that the AHI (r = -.469, P = .001) and the percentage of total sleep time with oxygen saturation < 90% (T90%; r = -.477, P = .001) correlated with temporal pRNFL thickness. Multiple linear regression showed that the AHI was negatively associated with temporal pRNFL thickness (β = -0.573, P = .003).

CONCLUSIONS

OSAS may cause subclinical temporal pRNFL thinning in the contralateral optic nerve among patients with unilateral NAION without any significant change in visual function. Advanced optic nerve observation and intervention may be warranted in patients with moderate-severe OSAS.

CITATION

Li X, Zhang Y, Guo T, et al. Influence of obstructive sleep apnea syndrome on the contralateral optic nerve in patients with unilateral nonarteritic anterior ischemic optic neuropathy. J Clin Sleep Med. 2023;19(2):347-353.

Hormone Replacement Therapy and the Incidence of Nonarteritic Anterior Ischemic Optic Neuropathy: a Nationwide Population-Based Study (2009-2018)

PURPOSE

This study aimed to assess the association between hormone replacement therapy (HRT) and the prevalence of nonarteritic anterior ischemic optic neuropathy (NAION) in menopausal women using national data from the entire Korean population.

METHODS

The health screening data of 1,381,605 women between 40 and 90 years of age collected by the National Health Insurance Service (NHIS) of Korea between January 1, 2009, and December 31, 2018, were retrospectively reviewed. Before data analysis, the potential cofounders were adjusted for among all participants. Based on HRT use and its duration (classified into four groups), the hazard ratio (HR) and 95% confidence interval (CI) of NAION development were calculated via a Cox proportional hazards regression analysis using the nonuser group as a reference.

RESULTS

Overall, 7824 NAION diagnoses were made during the mean follow-up of 8.22 years (standard deviation: 1.09 years) in 1,381,605 post-menopausal women. NAION was more common in the HRT group than in the non-HRT group (HR [95% CI]: 1.268 [1.197-1.344]). Furthermore, the risk of NAION increased along with increased HRT duration (p < 0.0001). In the multivariate analysis, the adjusted HRs of the < 2-year HRT group, the 2-5-year HRT group, and the ≥ 5-year HRT group were 1.19 (95% CI: 1.10-1.28), 1.3 (95% CI: 1.17-1.45), and 1.473 (95% CI: 1.31-1.65), respectively. Compared to women younger than 65 years, the HR of HRT for NAION was significantly higher than that of women older than 65 years (p < 0.0001).

CONCLUSION

Our population-based cohort study found that HRT was significantly associated with increased incidence of NAION. The incidence of NAION also increased with the duration of HRT.

Metabolic syndrome and its components are associated with non-arteritic anterior ischaemic optic neuropathy

PURPOSE

To determine whether metabolic syndrome (MetS) is a risk factor for various forms of optic neuropathy including non-arteritic anterior ischaemic optic neuropathy (NAION).

METHODS

This population-based analysis identified patients ≥40 years of age in Olmsted County, Minnesota, USA using the Rochester Epidemiology Project 2005-2018. Patients with MetS were identified if three or more of the five standard criteria for diagnosing MetS were present: systemic hypertension, hyperglycaemia, hypertriglyceridaemia, reduced high-density lipoprotein cholesterol (hypoalphalipoproteinaemia) and central adiposity defined by increased body mass index. Charts of patients identified as having an optic neuropathy were reviewed to record specific diagnoses and compared with patients without ocular pathology other than cataract. The odds ratio (OR) of association with MetS was calculated and adjusted for age, sex and race with multivariate analysis for the various optic neuropathies.

RESULTS

Patients with MetS were more likely to have an optic neuropathy than those without (OR 2.2, p<0.001). After adjusting for age, sex and race, the only optic neuropathy found to be significantly associated with MetS was NAION (OR 6.17, p=0.002). For patients with NAION, though each individual component of MetS was individually significantly associated with MetS, further analysis suggested that hypertriglyceridaemia, hypoalphalipoproteinaemia and hyperglycaemia were likely the key drivers in the overall significance between NAION and MetS.

CONCLUSION

Patients with MetS were more likely to have NAION. Further studies are needed to determine whether MetS is a modifiable risk factor for NAION.

Ischemic Optic Neuropathies: Current Concepts

Ischemic optic neuropathy (ION) is the term ascribed to optic nerve disease that is the result of a transient or permanent interruption of the blood supply to any portion of the optic nerve. Anterior ischemic optic neuropathy (AION) refers to ischemia of the optic nerve head, whereas posterior ischemic optic neuropathy (PION) indicates ischemia of the posterior optic nerve. IONs are primarily classified as arteritic ION and non-arteritic ION. A subset of ION that occurs around the time of surgery is termed peri-operative ION. These phenomena will be discussed as distinct entities.

Retinal microcirculation characteristics in obstructive sleep apnea/hypopnea syndrome evaluated by OCT-angiography: a literature review

PURPOSE

The retina may provide a window to estimate systemic vascular status; therefore, there has been interest in identifying microcirculation characteristics that possibly reflect hypoxic alterations in obstructive sleep apnea/hypopnea syndrome (OSAS). Emerging evidence has suggested that retinal microvasculature investigation holds the potential to characterize the pathophysiology involved in ocular manifestations of OSAS. The advent of optical coherence tomography angiography (OCT-A) has attracted significant attention as this technique offers detailed analysis of the retinal capillary plexus.

METHODS

A detailed literature search was performed in PubMed database until December 2021. We identified and reviewed all papers referring to the alterations of the retinal capillary plexus in OSAS using OCT-A.

RESULTS

A comprehensive update indicates that microcirculation alterations of the retinal capillary plexus utilizing OCT-A may differ with severity of OSAS and imply the potential underlying pathophysiology of ocular manifestations. The reviewed series have revealed variability concerning microvasculature characteristics at the macular and the peripapillary area. Further studies are warranted to establish the OCT-A parameters as biomarkers regarding the evaluation of OSAS in clinical practice.

CONCLUSION

Retinal capillary plexus characteristics as seen on OCT-A reflect microvasculature alterations, potentially leading to concomitant ocular comorbidity in the context of OSAS. The reviewed literature may confirm the diagnostic and prognostic value of OCT-A in the assessment of the pathophysiology of ocular manifestations in OSAS and highlight unmet needs to be addressed by future research.

Sleep and eye disease: A review

There is a growing body of literature on the effects of sleep disorders, in particular obstructive sleep apnoea (OSA), on ocular health, with consistent evidence of an increased risk of floppy eyelid syndrome, non-arteritic anterior ischaemic optic neuropathy, diabetic macular oedema, and other retinal vasculature changes in individuals with OSA. However, reports on OSA's associations with glaucoma, papilloedema, diabetic retinopathy, central serous chorioretinopathy, and keratoconus have been conflicting, while links between OSA and age-related macular degeneration have only been described fairly recently. Despite numerous suggestions that OSA treatment may reduce risk of these eye diseases, well-designed studies to support these claims are lacking. In particular, the ocular hypertensive effects of continuous positive airway pressure (CPAP) therapy for OSA requires further investigation into its potential impact on glaucoma risk and management. Reports of ocular surface complications secondary to leaking CPAP masks highlights the importance of ensuring good mask fit. Poor sleep habits have also been linked with increased myopia risk; however, the evidence on this association remains weak.

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.

The Association Between Obstructive Sleep Apnea and Cotton-Wool Spots in Nonproliferative Diabetic Retinopathy

Purpose:

This work reports the association of obstructive sleep apnea (OSA) and cotton-wool spots (CWS) seen in patients with nonproliferative diabetic retinopathy (DR).

Methods:

A random sample of patients diagnosed with DR between January 1, 2015 and December 31, 2018, were selected from medical-billing codes. Dilated funduscopic examination findings and medical history were analyzed by reviewing medical records.

Results:

CWS were present in 12 of 118 patients without OSA, compared with 11 of 32 patients with OSA (10.2% vs 34.4%, respectively; P = .002). OSA was more common in men (68.8%, P = .03) and associated with a higher body mass index (30.0 ± 5.0 without OSA vs 33.6 ± 5.5 with OSA, P < .001). When comparing those with and without OSA, there was no association with age; glycated hemoglobin A1c; stage of DR; insulin dependence; presence of diabetic macular edema; smoking status; or a history of hypertension, hyperlipidemia, cardiovascular disease, or other breathing disorder.

Conclusions:

The presence of OSA is associated with CWS in patients with DR, as well as male sex and a higher body mass index. Further research is needed to determine the ophthalmologist’s role in the timely referral of patients with CWS for OSA evaluation.

Risk Factors for Non-arteritic Anterior Ischemic Optic Neuropathy: A Large Scale Meta-Analysis

Objective: We conducted a meta-analysis to explore all the potential risk factors for non-arteritic anterior ischemic optic neuropathy (NAION) based on the published literature. Methods: A comprehensive literature search through the online databases was performed to obtain studies concerning the risk factors of NAION up to June 2020. Pooled unadjusted odds ratios (ORs) or rate ratios (RRs) were calculated to evaluate the weight of risk factors. This study was registered in PROSPERO under the number CRD42018084960. Results: Our meta-analysis included 49 original studies comprising of more than 10 million patients. The following risk factors were proved to be significantly associated with NAION: male gender (OR = 1.67, 95% CI: 1.50-1.85, P < 0.00001), hypertension (RR = 1.28, 95% CI: 1.20-1.37, P < 0.00001), hyperlipidemia (RR = 1.43, 95% CI: 1.26-1.62, P < 0.00001), diabetes mellitus (DM) (RR = 1.53, 95% CI: 1.36-1.73, P < 0.00001), coronary heart disease (CHD) (RR = 1.68, 95% CI: 1.24-2.27, P = 0.0008), sleep apnea (RR = 3.28, 95% CI: 2.08-5.17, P < 0.00001), factor V Leiden heterozygous (RR = 2.21, 95% CI: 1.19-4.09, P = 0.01), and medication history of cardiovascular drugs. Conclusion: We concluded that the above risk factors were significantly related to NAION. Better understanding of these risk factors in NAION can help the direct therapeutic approaches.

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.

7,8-Dihydroxyflavone protects retinal ganglion cells against chronic intermittent hypoxia-induced oxidative stress damage via activation of the BDNF/TrkB signaling pathway

PURPOSE

Chronic intermittent hypoxia (CIH) plays a key role in the complications of obstructive sleep apnea (OSA), which is strongly associated with retinal and optic nerve diseases. Additionally, the brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase B (TrkB) signaling pathway plays an important protective role in neuronal injury. In the present study, we investigated the role of 7,8-dihydroxyflavone (7,8-DHF) in regulating CIH-induced injury in mice retinas and rat primary retinal ganglion cells (RGCs).

METHODS

C57BL/6 mice and in vitro primary RGCs were exposed to CIH or normoxia and treated with or without 7,8-DHF. The mice eyeballs or cultured cells were then taken for histochemistry, immunofluorescence or biochemistry, and the protein expression of the BDNF/TrkB signaling pathway analysis.

RESULTS

Our results showed that CIH induced oxidative stress (OS) in in vivo and in vitro models and inhibited the conversion of BDNF precursor (pro-BDNF) to a mature form of BDNF, which increased neuronal cell apoptosis. 7,8-DHF reduced the production of reactive oxygen species (ROS) caused by CIH and effectively activated TrkB signals and downstream protein kinase B (Akt) and extracellular signal-regulated kinase (Erk) survival signaling pathways, which upregulated the expression of mature BDNF. ANA-12 (a TrkB specific inhibitor) blocked the protective effect of 7,8-DHF.

CONCLUSION

In short, the activation of the BDNF/TrkB signaling pathway alleviated CIH-induced oxidative stress damage of the optic nerve and retinal ganglion cells. 7,8-DHF may serve as a promising agent for OSA related neuropathy.

Evaluation of hemodynamic changes in nonarteritic anterior ischemic optic neuropathy using multimodality imaging

Background

Nonarteritic anterior ischemic optic neuropathy (NAION) patients experience hypo-perfusion in the short posterior ciliary arteries (SPCAs), however, the cause of hypo-perfusion is unclear. Real-time dynamic hemodynamic observations may provide clues into specific NAION pathogenic mechanisms. We aim to analyze hemodynamic changes occurring in NAION using multimodality imaging. Our specific focus is identifying pathogenic mechanisms underlying SPCA insufficiency in NAION.

Methods

Three-dimensional arterial spin labeling (3D ASL) magnetic resonance imaging (MRI) and three-dimensional time-of-flight (3D-TOF) magnetic resonance angiography (MRA) were performed on 25 NAION patients (50 eyes) and 22 (44 eyes) normal cases were recruited. The diameter of the initial part of the ophthalmic artery and internal carotid artery siphon were measured using MRA. Blood vessel identification and blood flow (BF) were detected using 3D ASL MRI. We measured BF values of the optic nerve head (ONH) region of the retina/choroid complex, optic nerve (ON), temporal lobe, and occipital lobe.

Results

We studied 32 NAION affected eyes, 18 NAION uninvolved eyes, and 44 normal eyes. Diameter of the initial part of ophthalmic artery in the NAION affected eyes was significantly larger than the uninvolved eyes (P=0.026). Diameter of the NAION eyes was 1.33±0.19 mm [mean ± standard deviation (SD)], uninvolved eyes were 1.15±0.21 mm. At a photolabeling delay times (PLD) of 1,500 and 2,500 ms, BF of the ONH and ON in NAION affected eyes was significantly less than uninvolved and normal eyes (pONH <0.001 both at 1,500 and 2,500 ms, pON <0.001 and pON =0.001 at 1,500 and 2,500 ms, respectively). ONH of uninvolved eyes was also significantly less than normal eyes. Additionally, BF of the ONH region correlated with temporal lobe BF, with an R²=0.3231 and 0.2397 at 1,500 and 2,500 ms, respectively. BF of the ONH region also correlated with occipital lobe BF, with an R²=0.2534 and 0.4397 at 1,500 and 2,500 ms, respectively. ON and temporal lobe BF also correlated, with an R²=0.226 and 0.1504 at 1,500 and 2,500 ms, respectively.

Conclusions

Abnormal hemodynamics of small cerebral vessels existed prior to the onset of NAION. A candidate mechanism underlying NAION appears to be transient insufficiency of blood supply and decompensation of ocular vascular regulation.

Association Between Sleep Apnea Risk Score and Retinal Microvasculature Using Optical Coherence Tomography Angiography

PURPOSE

To investigate the retinal vessel changes at peripapillary and parafoveal regions using optical coherence tomography angiography in patients with varying obstructive sleep apnea syndrome (OSAS) risk, identified by the STOP-BANG questionnaire.

DESIGN

Prospective, hospital-based cross-sectional study.

METHODS

Participants were divided into 3 groups based on the OSAS risk score. Flow areas and vessel densities were calculated at peripapillary and parafoveal regions using optical coherence tomography angiography. Microvasculature changes between the 3 groups and correlation between OSAS risk score and vascular changes were calculated.

RESULTS

Six hundred and six eyes of 303 patients were included in groups 1 (n = 96), 2 (n = 135), and 3 (n = 72). In patients with high OSAS risk, an increase in flow areas (P = .011) and vessel densities (P = .002) in superficial capillary plexus was noted. In contrast, flow areas (P = .003) and vessel densities (P < .000) in deep capillary plexus were reduced. Positive correlation was noted between sleep scores and vessel densities in superficial capillary plexus (P = .04). Negative correlation was noted between sleep scores and flow areas (P = .003) and vessel densities (P ≤ .001) in deep capillary plexus.

CONCLUSION

The sleep apnea questionnaire is an easy method of identifying the disease severity stage, but polysomnography still remains the definitive gold standard. Optical coherence tomography angiography shows some associations with disease severity, but it cannot be used unambiguously to distinguish the severity of sleep apnea.

Neuro-Ophthalmological Manifestations of Obstructive Sleep Apnea: Current Perspectives

Obstructive sleep apnea (OSA) is a disease of obstructed airways during sleep that significantly impacts the quality of life and increases the risk of various systemic diseases. OSA has been studied as a risk factor for a number of neuro-ophthalmic conditions and a strong relationship has been established with non-arteritic anterior ischemic optic neuropathy (NAION). The incidence of glaucoma and stroke have also been significantly associated with OSA and are conditions that may also be seen by neuro-ophthalmologists. Patients with NAION have a significantly higher incidence of OSA and OSA diagnosis significantly increases the risk for NAION development. Non-compliance with continuous positive airway pressure (CPAP) in OSA patients has also been found to be a risk factor for fellow-eye involvement and there is increasing evidence to suggest that every patient with NAION should be formally evaluated with polysomnography. The relationship between OSA and idiopathic intracranial hypertension (IIH) has also been studied, but the relationship between these two conditions is less clear. There is insufficient evidence to recommend routine eye examinations in OSA patients for papilledema and conducting a sleep study for a newly diagnosed IIH patient should be left to the discretion of the clinician based on other symptoms and risk factors of OSA.