Obstructive sleep apnea and optic neuropathy: is there a link?

[Primary open angle glaucoma and sleep apnea syndrome: A review of the literature]

The relationship between glaucoma and Obstructive Sleep Apnea Syndrome (OSAS) has long been discussed, with conflicting study findings. OSAS appears in the most recent studies to be more of an aggravating factor than an independent risk factor for glaucoma. Patients with OSAS may develop a more rapid progression of primary open-angle glaucoma (POAG). OSAS may damage the optic nerve not only by increasing the intraocular pressure (IOP) but also by altering the blood supply to the optic nerve as shown by more recent work with OCT-Angiography. Although the systemic benefits of Continuous Positive Airway Pressure (CPAP) have been demonstrated, few studies have evaluated its effect on the optic nerve. CPAP might act on glaucomatous neuropathy by improving the blood supply to the optic nerve. The study of this mechanism of action might provide new insights into the relationship between OSAS and glaucoma.

Obstructive Sleep Apnea in Men With Idiopathic Intracranial Hypertension: A Prospective Case-Control Study

BACKGROUND

Idiopathic intracranial hypertension (IIH) is uncommon in men. Previous studies reported on high frequency of obstructive sleep apnea (OSA) in men with IIH, but the pathophysiology of this association remains unclear. One possible culprit for increased intracranial pressure in patients with OSA is hypercapnia. The purpose of this study was to compare the rate of hypercapnia during polysomnography (PSG) study in men with and without IIH and to report on the rate and severity of OSA in men with IIH compared with control subjects of similar age and body mass index (BMI).

METHODS

Prospective case-control study of male patients diagnosed with IIH underwent PSG with continuous oxygen and carbon dioxide monitoring overnight. Healthy control subjects with similar age and BMI also underwent PSG. The incidence of OSA diagnosis, rate of hypercapnia and hypoxia, and apnea hypopnea index (AHI) were compared between 2 groups.

RESULTS

Eleven subjects with IIH and 10 controls underwent PSG. Both groups were similar regarding age and BMI on the Mann-Whitney U test ( P = 0.072 for age, P = 0.251 for BMI). Subjects for whom carbon dioxide data were not available for more than 50% of total sleep time were excluded from hypercapnia analysis. The mean age was 41.9 years, and the mean BMI was 33.8 kg/m 2 in subjects and controls. OSA was diagnosed in 9 of 11 men with IIH and 4 of 10 controls. There was no statistically significant difference in the rate of hypercapnia and hypoxia between 2 groups for whom the data were available. All patients with BMI over 30 kg/m 2 (7 of 7) and 50% (2 of 4) controls with BMI over 30 kg/m 2 were diagnosed with OSA compared with 50% (2 of 4) of cases and 33% (2 of 6) of controls with BMI less than 30 kg/m 2 . BMI was a significant predictor of total AHI ( P = 0.042) and OSA severity ( P = 0.023), but IIH diagnosis was not ( P > 0.05).

CONCLUSIONS

There was no difference in hypercapnia rate between men with IIH and controls; thus, hypercapnia is an unlikely causative factor in pathophysiology of IIH. OSA on PSG was almost 2 times as prevalent in patients with IIH compared with controls; however, BMI was the strongest predictor of OSA diagnosis, and most patients (9 of 11) with BMI over 30 kg/m 2 had OSA on PSG. In men with BMI less than 30, the rate of OSA on PSG study was higher in men with IIH. Based on these data, we recommend that all men with the diagnosis of IIH should undergo PSG study.

Retinal abnormalities, although relatively common in sleep clinic patients referred for polysomnography, are largely unrelated to sleep-disordered breathing

Study objectives.

There has been long-standing interest in potential links between obstructive sleep apnea (OSA) and eye disease. This study used retinal photography to identify undiagnosed retinal abnormalities in a cohort of sleep clinic patients referred for polysomnography (PSG) and then determined associations with PSG-quantified sleep-disordered breathing (SDB) severity.

Methods

Retinal photographs (n = 396 patients) were taken of each eye prior to polysomnography and graded according to validated, standardized, grading scales. SDB was quantified via in-laboratory polysomnography (PSG; n = 385) using standard metrics. A questionnaire (n = 259) documented patient-identified pre-existing eye disease. Within-group prevalence rates were calculated on a per patient basis. Data were analyzed using multivariate logistic regression models to determine independent predictors for retinal abnormalities. P < 0.05 was considered significant.

Results

Main findings were (1) 76% of patients reported no pre-existing “eye problems”; (2) however, 93% of patients had at least one undiagnosed retinal photograph-identified abnormality; (3) most common abnormalities were drusen (72%) and peripapillary atrophy (PPA; 47%); (4) age was the most common risk factor; (5) diabetes history was an expected risk factor for retinopathy; (6) patients with very severe levels of SDB (apnea hypopnea index ≥ 50 events/h) were nearly three times more likely to have PPA.

Conclusion

Retinal photography in sleep clinic settings will likely detect a range of undiagnosed retinal abnormalities, most related to patient demographics and comorbidities and, except for PPA, not associated with SDB. PPA may be indicative of glaucoma, and any association with severe SDB should be confirmed in larger prospective studies.

Is Genetic Risk for Sleep Apnea Causally Linked With Glaucoma Susceptibility?

Purpose

Observational studies have suggested that individuals with pre-existing sleep apnea (SA) have up to double the risk of developing glaucoma than individuals without SA. Understanding risk factors for glaucoma is important to assist with well-structured screening, early intervention, and efficient allocation of specialist consultation. The objective of this study is therefore to use genetic data to determine whether SA is a causal risk factor for glaucoma.

Methods

Two-sample Mendelian randomization (MR) analyses were performed to assess the association between genetically predicted SA and glaucoma susceptibility using genome-wide association study (GWAS) of 25,062 SA cases, 313,372 controls derived from 23andMe and summary data from a glaucoma GWAS meta-analysis (20,582 cases, 119,318 controls), including individuals of European descent, mainly from the UK Biobank.

Results

Inverse variance weighted regression of genetic susceptibility for SA on risk of glaucoma revealed no strong evidence for an association between SA and glaucoma (OR = 0.95, 95% confidence intervals = 0.84–1.07), results were consistent across all MR predictors.

Conclusions

We found little genetic evidence supporting a causal association between SA and glaucoma. Our results refute the possibility of a large effect (glaucoma OR > 1.5 per doubling of odds on SA) between SA and glaucoma.

Prospective evaluation of the comorbidity of obstructive sleep apnea in patients with glaucoma

STUDY OBJECTIVES

This study aimed to identify prospectively the correlation between obstructive sleep apnea (OSA) severity, ocular microcirculation changes, and visual function changes in patients with glaucoma.

METHODS

We prospectively enrolled patients with glaucoma who were willing to undergo overnight polysomnography. The enrolled patients were further divided into normal tension glaucoma, high-tension glaucoma, and control. Visual field progression was analyzed using sequential standard automated perimetry. Peripapillary and macular vessel density were assessed through optical coherence tomography angiography (OCT-angiography). The associations between polysomnography parameters, OCT-angiography parameters, and visual field progression were analyzed.

RESULTS

A total of 22 patients with normal tension glaucoma, 30 patients with high-tension glaucoma, and 24 control patients were enrolled. Through regression analysis, glaucoma was found to be an independent predictor of moderate-to-severe OSA (P = .035); furthermore, moderate-to-severe OSA was significantly associated with visual field progression (P = .008 in the high-tension glaucoma subgroup and P = .008 in the overall glaucoma). Additionally, OSA severity was negatively correlated with the ganglion cell complex thinning rate in the normal tension glaucoma subgroup.

CONCLUSIONS

Presence of glaucoma increased the risk of moderate-to-severe OSA compared with the control group. OSA severity was related to visual field deterioration in patients with glaucoma and further associated with structural progression in the normal tension glaucoma subgroup. Careful monitoring of the comorbid OSA status of patients with glaucoma is essential to prevent disease progression.

CITATION

Chan Y-H, Chuang L-H, Yu C-C, et al. Prospective evaluation of the comorbidity of obstructive sleep apnea in patients with glaucoma. J Clin Sleep Med. 2022;18(1):47-56.

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 Importance of Diagnosing and the Clinical Potential of Treating Obstructive Sleep Apnea to Delay Mild Cognitive Impairment and Alzheimer's Disease: A Special Focus on Cognitive Performance

Obstructive sleep apnea (OSA) is a highly frequent sleep disorder in the middle-aged and older population, and it has been associated with an increased risk of developing cognitive decline and dementia, including mild cognitive impairment (MCI) and Alzheimer's disease (AD). In more recent years, a growing number of studies have focused on: 1) the presence of OSA in patients with MCI or AD, 2) the link between OSA and markers of AD pathology, and 3) the role of OSA in accelerating cognitive deterioration in patients with MCI or AD. Moreover, some studies have also assessed the effects of continuous positive airway pressure (CPAP) treatment on the cognitive trajectory in MCI and AD patients with comorbid OSA. This narrative review summarizes the findings of studies that analyzed OSA as a risk factor for developing MCI and/or AD in the middle-aged and older populations with a special focus on cognition. In addition, it describes the results regarding the effects of CPAP treatment in hampering the progressive cognitive decline in AD and delaying the conversion to AD in MCI patients. Considering the importance of identifying and treating OSA in patients with MCI or AD in order to prevent or reduce the progression of cognitive decline, further larger and adequately powered studies are needed both to support these findings and to set programs for the early recognition of OSA in patients with cognitive impairment.

Evaluation of Retinal Nerve Fiber Layer Thickness and Optic Nerve Head Parameters in Obstructive Sleep Apnoea Patients

PURPOSE

To study the retinal nerve fiber layer (RNFL) thickness and optic nerve head (ONH) parameters in obstructive sleep apnoea (OSA) patients and their relationship with severity of the disease.

METHODS

A cross-sectional, hospital-based study. Fifty-four OSA subjects and 54 controls were recruited. Candidate that fulfil the criteria with normal ocular examinations then proceed with spectrum domain Cirrus optical coherence tomography examinations. ONH parameters and RNFL thickness were evaluated. Apnoea-hypopnoea index (AHI) of the OSA group were obtained from the medical record.

RESULTS

In OSA, mean of average RNFL thickness was 93.87 µm, standard deviation (SD) = 9.17, p = 0.008 (p < 0.05) while superior RNFL thickness was 113.59 µm, SD = 16.29, p ≤ 0.001 (p < 0.05). RNFL thickness fairly correlate with severity of the disease (AHI), superior RNFL with R = 0.293, R2 = 0.087, p = 0.030 (p < 0.05), and nasal RNFL R = 0.292, R2 = 0.085, p = 0.032. No significant difference and correlation observed on ONH parameters. In control group, mean of average RNFL thickness was 98.96 µm, SD = 10.50, p = 0.008 (p < 0.05) while superior RNFL thickness was 125.76 µm, SD = 14.93, p ≤ 0.001 (p < 0.05).

CONCLUSIONS

The mean of the average and superior RNFL thickness were significantly lower in the OSA group compare to control. Regression analysis showed RNFL thickness having significantly linear relationship with the AHI, specifically involving the superior and nasal quadrant.

Can Extra Daytime Light Exposure Improve Well-Being and Sleep? A Pilot Study of Patients With Glaucoma

Glaucoma damages retinal ganglion cells, including intrinsically photosensitive retinal ganglion cells (ipRGCs). These cells modulate various non-visual physiological and psychological functions which are modulated by light. In patients with glaucoma, we assessed the effect of daily bright light exposure (LE) on several melanopsin-dependent functions, such as the pupil constriction, circadian rest-activity cycles, sleep and subjective well-being including relaxation, alertness and mood. Twenty patients participated in the study (9 women, 11 men, mean age = 67.6 ± 7.5 y). Pupillometry was performed before the LE weeks and repeated on the last day of LE. The post-illumination pupil response (PIPR) was calculated as a proxy for melanopsin-dependent activation. Participants continuously wore an activity monitor and self-assessed sleep quality, well-being and visual comfort for 7 days before and during 4 weeks of daily bright LE (30 min to 10,000 lux polychromatic bright white light). After the LE, there was a significantly greater PIPR and higher subjective sleep quality when compared to the pre-LE week (p < 0.05), but no significant changes in 24-h rhythms or sleep parameters. A greater PIPR was correlated with an increase in circadian amplitude and higher inter-daily stability (derived from rest-activity cycles; p < 0.05). In a small group of patients with glaucoma, scheduled daily bright light exposure could improve subjective sleep quality. These findings highlight the importance to evaluate and maintain non-visual functions at different levels in patients with progressive loss of ipRGCs.

Links between obstructive sleep apnea and glaucoma neurodegeneration

In the last few years, the possible link between obstructive sleep apnea (OSAS) and glaucoma, has attracted the interest of many scientists, especially in those forms of primary open angle glaucoma (POAG) and normal tension glaucoma (NTG), in which a progression of the disease occurs, even though intraocular pressure (IOP) is in the range of normality. The increased prevalence of POAG or NTG in patients affected by OSAS, and vice versa, has stimulated interest in the pathogenetic mechanisms that could trigger these two diseases. Hypoxia generated by apnea/hypopnea cycles has been identified as the main cause of many changes in the vascular and neurological systems, which alter the functioning not only of the optic nerve, but also of the whole organism. However, many other factors could be involved, like mechanical factors, obesity, hormonal imbalance and other sleep disorders. Furthermore, the demonstration of typical glaucomatous or glaucoma-like changes in the anatomy or function of the optic nerve and retinal nerve fiber layer by sensitive specific and diagnostic methods, such as perimetry, optical coherence tomography (OCT), optical coherence tomography angiography (OCTA) and electrophysiological exams keeps interest high for this field of study. For this reason, further investigations, hopefully a source of stronger scientific evidences, are needed.

Obstructive Sleep Apnea in Patients With Primary-open Angle Glaucoma: No Role for a Screening Program

PRéCIS:: In this study, we found a high prevalence of obstructive sleep apnea (OSA) among patients with primary open-angle glaucoma (POAG) but this was not different (nor was OSA more severe) to matched people without glaucoma.

RATIONALE

It has been proposed that OSA might be a contributing factor in the development of POAG and by extension that there could be a role for screening people with POAG for OSA.

OBJECTIVES

To assess whether the prevalence of OSA among patients with POAG is different from that in people without glaucoma and to examine for associations between apnea-hypopnea index (AHI) and markers of functional and structural changes in POAG.

METHODS

Unselected POAG patients and control subjects were consecutively recruited in a single center. A comprehensive ocular assessment and nocturnal multichannel cardiorespiratory monitoring were performed.

RESULTS

Data from 395 participants, 235 POAG patients, and 160 controls were analyzed. The prevalence of OSA was 58% [95% confidence interval (CI), 52-65] in POAG patients and 54% (95% CI, 47-62) in controls, with 22% (95% CI, 16-27) of POAG patients and 16% (95% CI, 11-22) of controls diagnosed with moderate or severe OSA. A total of 160 POAG participants were matched to the controls using propensity score matching. There was no significant difference in OSA prevalence between the matched groups (P=0.91 for AHI≥5 and P=0.66 for AHI≥15). The AHI was not associated with the severity of visual field defect or retinal nerve fiber layer thinning after adjustment for confounders.

CONCLUSIONS

This study confirms a high prevalence of OSA among patients with POAG which is, however, not higher than in people without glaucoma matched for known OSA risk factors. Our results do not support screening for OSA in patients with POAG.

Evaluation of effects of positive airway pressure treatment on retinal fiber thickness and visual pathways using optic coherence tomography and visual evoked potentials in the patients with severe obstructive sleep apnea syndrome

INTRODUCTION

Hypoxia during sleep in obstructive sleep apnea syndrome (OSAS) increases intracranial pressure, decreases cerebral perfusion pressure, and alters vascular supply to the optic nerve. Pattern visual evoked potential (pVEP) has revealed that it causes alterations in the optic nerve, and optic coherence tomography has shown that it causes alterations in the retinal and macular layers.

OBJECTIVES

To detect and compare possible alterations in macula and peripapillary retinal nerve fiber thickness (pRNFL) using OCT and in the optic nerve pathways using pVEP before and after positive airway pressure (PAP) in the patients with severe OSAS.

MATERIALS AND METHODS

Thirty patients who were diagnosed as having severe OSAS in the neurology-sleep outpatient clinic and 30 healthy control subjects were included in the study. Ophthalmic examinations were performed prior to (month 0) and after (month 6) PAP treatment, and pVEP (peak time [PT] and amplitude) and OCT parameters (peripapillary retinal-macular layers) were compared.

RESULTS

In the comparison between the severe OSAS (before treatment) and control groups, thinning was found in pRNFL (average, nasal, inferior) and in the macular layers (external and internal superior quadrants) (p < 0.05). pVEP investigation revealed increased PT in P100 and N145 waves and decreased amplitude of N75-P100 waves. In the comparisons before and after PAP treatment, a decrease in PT of N75 and P100 waves and increase in N75-P100 amplitudes were found. In the pRNFL, significant thickening was found in the layers with thinning before treatment, whereas no significant thickening was found in macular layers, except for the fovea.

DISCUSSION

It was shown that PAP treatment in patients with severe OSAS prevents hypoxia without causing alterations in intraocular pressure and thus reduces inflammation and causes thickening in the pRNFL and macular layers.

Effect of Obstructive Sleep Apnea on Corneal Morphological Characteristics

PURPOSE

To determine central corneal thickness (CCT) and the corneal parameters in patients with obstructive sleep apnea (OSA), evaluate the relationship between the severity of OSA, minimum peripheral capillary oxygen saturation (min. SpO2), and corneal morphological characteristics.

METHODS

Patients with OSA diagnosed by full-night polysomnography before treatment were included. Patients with OSA were divided into 3 groups according to the Apnea-Hypopnea Index (AHI). The control group (CG) was examined to exclude the possibility of OSA and ocular diseases. The following data were recorded: age, sex, body mass index, ophthalmologic evaluation, and the results of polysomnography.

RESULTS

A total of 114 eyes were studied: 74 eyes of patients with OSA and 40 eyes of the CG. The mean age was 57 ± 6 years. The mean values of CCT and endothelial cell density (ECD) varied significantly between the patients and the CG (P < 0.001). The mean values of CCT, ECD, cell variation coefficient (CV), and hexagonal cell percentage (HEX) in the group of patients with OSA were 535.28 ± 21.32 μm, 2632 ± 333, cells/mm. 31.8 ± 3.9, and 55.6 ± 6.9%, respectively. The mean CCT and ECD values for each group were lower than those for the CG. A significant negative correlation was found between CCT and ECD for AHI values (r = -0.390, P = 0.011 and r = -0.109, P = 0.040, respectively), and a weak positive correlation between CCT and ECD was found for min. SpO2 (r = 0.282, P = 0.020 and r = 0.332, P = 0.018, respectively). CV and HEX did not significantly differ between the groups and did not correlate with the results of polysomnography.

CONCLUSIONS

Hypoxia is associated with significant changes in CCT and ECD. In patients with OSA, these parameters varied significantly when compared with the subjects in the CG. The severity of hypoxemia and the increase in AHI values reduce CCT and ECD in patients.

Evaluation of retinal fiber thickness and visual pathways with optic coherence tomography and pattern visual evoked potential in different clinical stages of obstructive sleep apnea syndrome

PURPOSE

To investigate the possible changes in retinal nerve fiber layer (RNFL) by optic coherence tomography and in the amplitudes and peak times (PTs) in pattern visual evoked potential (pVEP) and to compare them in obstructive sleep apnea syndrome (OSAS).

METHODS

This prospective study included patients with mild OSAS (n = 30), severe OSAS (n = 30), and 30 control subjects. All patients were assessed after obtaining the approval from our hospital's ethics committee.

RESULTS

There was no difference in age and gender between the groups (p = 0.184, p = 0.954). By analysis of variance, there was a significant difference in RNFL values among patients with mild OSAS, severe OSAS, and control for three measures of RNFL (average p = 0.044, nasal p = 0.003, inferior p = 0.027). In severe OSAS group, nasal and inferior quadrants of the RNFL were found to be thinner than the control group (p = 0.008, p = 0.031). We showed that the PT of P100 and N145 was prolonged in severe OSAS compared to the control group (p < 0.001) and that PT of P100 was prolonged in mild OSAS compared to the control group (p < 0.05). The amplitude of N75-P100 was significantly decreased in patients with both severe OSAS and mild OSAS compared to the control group (p < 0.001). Correlation of RNFL and pVEP values showed that the inferior quadrant RNFL thickness is correlated with both P100 and N145 PTs (r = 0.271*, p = 0.036 and r = 0.290*, p = 0.043, respectively) and N75-P100 amplitude (r = 0.378**, p = 0.003) in severe OSAS group.

CONCLUSIONS

In mild and severe stages of the disease, edema and inflammation were evident and VEP PT and amplitudes were affected in both groups. Furthermore, thinning in RNFL in the severe stage of the disease might be associated with higher atrophy levels and prolonged exposure to hypoxia.

The Development of Glaucoma after Surgery-Indicated Chronic Rhinosinusitis: A Population-Based Cohort Study

This study investigates the development of glaucoma in subjects with surgery-indicated chronic rhinosinusitis (CRS) by the use of the National Health Insurance Research Database in Taiwan. Individuals that received the functional endoscopic sinus surgery (FESS) with a diagnostic code of CRS were regarded as surgery-indicated CRS and enrolled in the study group. Four non-CRS patients were age- and gender-matched to each patient in the study group. The exclusion criteria included legal blindness, ocular tumor, history of eyeball removal, and previous glaucoma. The outcome was regarded as the development of glaucoma, and conditional logistic regression was used for the statistical analysis, which involved multiple potential risk factors in the multivariate model. A total of 6506 patients with surgery-indicated CRS that received FESS and another 26,024 non-CRS individuals were enrolled after exclusion. The age and gender distributions were identical between the two groups due to matching. There were 108 and 294 glaucoma events in the study group and control group, respectively, during the follow-up period, and the study group had a significantly higher adjusted hazard ratio (1.291, 95% confidential interval: 1.031–1.615). The cumulative probability analysis also revealed a correlation between the occurrence of glaucoma and the CRS disease interval. In the subgroup analysis, the chance of developing open-angle glaucoma and normal-tension glaucoma was significantly higher in the study group than in the control group. In conclusion, the existence of surgery-indicated CRS is a significant risk factor for the development of glaucoma, which correlated with the disease interval.

Impact of Obstructive Sleep Apnea on Optic Nerve Function in Patients With Craniosynostosis and Recurrent Intracranial Hypertension

PURPOSE

Assessment of combined impact of intracranial hypertension (ICH) and obstructive sleep apnea (OSA) on optic nerve function in children with craniosynostosis (CS).

DESIGN

Retrospective cross-sectional study.

METHODS

Patients treated at Boston Children's Hospital for CS who had an ophthalmic examination that included pattern reversal (pr)VEP (2013-2014) and history of ICH based on direct measurement, papilledema, or classic features on neuroimaging and during cranial vault expansion were included. History of OSA was determined by polysomnography and associated conditions, including apnea and (adeno)tonsillectomy. Subjects were divided into 4 groups: group 1, resolved ICH absent history of OSA; group 2, resolved ICH with history of OSA; group 3, recurrent ICH absent history of OSA; and group 4, recurrent ICH with history of OSA. Predictor variables included latency of P100 component of pattern-reversal visual evoked potential, best-corrected visual acuity, optic nerve appearance, visual fields, and global retinal nerve fiber layer. Primary outcome was association of prolonged P100 latency with resolved vs recurrent ICH and OSA.

RESULTS

Twenty-eight children met inclusion criteria (mean age 11.6 ± 6.9 years): group 1 (n = 3), group 2 (n = 6), group 3 (n = 8), and group 4 (n = 11). P100 latencies were not prolonged in groups 1 and 2. Three of 8 in group 3 and 9 of 11 in group 4 had prolonged P100 latency. Group 4 was significantly worse than group 3 (P = .005).

CONCLUSIONS

History of OSA, in addition to recurrent ICH, is associated with greatest risk of optic neuropathy with CS. Ophthalmologists should encourage early management of OSA as well as ICH to optimize ophthalmic outcomes.

Chronic Intermittent Hypoxia Alters Rat Ophthalmic Artery Reactivity Through Oxidative Stress, Endothelin and Endothelium-Derived Hyperpolarizing Pathways

Purpose

Obstructive sleep apnea recently has been associated with a higher frequency of ischemic optic neuropathies. Intermittent hypoxia (IH) has been proposed as a major component of obstructive sleep apnea cardiovascular consequences. However, there currently are no pathophysiologic data regarding the effect of IH on the ocular vascular system. Thus, we assessed the impact of chronic IH exposure on the morphology and vascular reactivity of the rat ophthalmic artery (OA).

Methods

Rats were exposed to 14 days of IH or normoxia (NX). Ophthalmic artery reactivity was studied using wire myography in rats treated or not with tempol (1 mM/day). Expression of endothelin-1 (ET-1) and its receptors, and of the three nitric oxide synthase (NOS) isoform genes was quantified using quantitative polymerase chain reaction (qPCR) in the retina and optic nerve. Structural alterations (optical and electron microscopy) and superoxide anion production were studied in OA sections.

Results

Superoxide ion expression in the OA wall was increased by 23% after IH exposure. Ophthalmic artery contractile response to 3.10-8 M ET-1 was increased by 18.6% and nitric oxide-mediated relaxation was significantly delayed in IH compared to NX rats. In the absence of nitric oxide, cytochrome P450 blockade increased relaxation to acetylcholine in IH rats and delayed it in NX rats. Tempol treatment abolished the IH-induced changes in OA reactivity.

Conclusions

These results strongly suggest that chronic IH induces oxidative stress in the rat OA, associated with endothelial dysfunction through alterations of nitric oxide and endothelium-derived hyperpolarising factors (EDHF) pathways.

Nonarteritic anterior ischaemic optic neuropathy and its association with obstructive sleep apnoea: a health insurance database study

BACKGROUND

Nonarteritic anterior ischaemic optic neuropathy (NAION) is the most common acute optic neuropathy in old age. Although there are several known risk factors, the influence of obstructive sleep apnoea (OSA) has not been completely elucidated. The aim of this study was to evaluate the association between NAION and OSA.

METHODS

This retrospective, longitudinal cohort study used the national health insurance database of Taiwan covering the period 1996-2013. Patients without NAION at the diagnosis of OSA or who developed NAION 1 year after the diagnosis of OSA were enrolled. The patients were followed until death or the last day of the study. Cox proportional hazard regression was used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) to investigate the association between OSA and NAION.

RESULTS

There were 8488 patients in the OSA group and 33 952 in the control group (without OSA), for a ratio of approximately 1:4. The percentages of NAION were 0.36% and 0.2% in the OSA and control groups, respectively, with a statistically significant difference (p < 0.01; chi-square test), and this significant difference remained in multivariate analysis (p = 0.019) with a significantly higher HR (1.66; 95% CI: 1.08-2.55). There was significant difference in the 30-39 years age group in multivariate analysis (p < 0.01, HR: 6.30; 95% CI: 2.28-17.40).

CONCLUSION

There was a strong association between NAION and OSA, and the patients with OSA had a higher risk of NAION. Further large-scale, prospective studies are warranted to evaluate the effect of OSA on developing NAION.

Continuous Positive Airway Pressure Treatment May Improve Optic Nerve Function in Obstructive Sleep Apnea: An Electrophysiological Study

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is a sleep disorder frequently associated with optic nerve diseases. Moreover, untreated patients with severe OSA may show optic nerve dysfunction as documented by electrophysiological studies using visual evoked potentials (VEP). Because continuous positive airway pressure (CPAP) treatment has proved to restore the physiologic nocturnal breathing, thus preventing nocturnal hypoxemia and reducing inflammation, in this study we tested whether 1-year CPAP treatment may modify VEP responses in patients with severe OSA.

METHODS

VEP were recorded at baseline and after 1 year of CPAP treatment in 20 patients with severe OSA, divided in two groups on the basis of CPAP adherence, and compared to a healthy control group.

RESULTS

Patients with good adherence to CPAP therapy (CPAP+; n = 10) showed VEP P100 amplitude significantly higher than patients with poor adherence to CPAP therapy (CPAP-; n = 10). Moreover, the CPAP+ group showed VEP responses similar to those in the control group (n = 26). Considering the mean difference of VEP responses between baseline and follow-up, the CPAP+ group showed a significant increase in VEP P100 amplitude and a significant decrease in VEP P100 latency compared to the CPAP- group.

CONCLUSIONS

This study documented that CPAP therapy significantly improves VEP in patients with OSA who are adherent to the treatment. We hypothesize that CPAP treatment, minimizing the metabolic, inflammatory and ischemic consequences of OSA, may normalize the altered VEP responses in patients with OSA by restoring and preserving optic nerve function.

Association between obstructive sleep apnea and optic neuropathy: a Taiwanese population-based cohort study

PURPOSE

Obstructive sleep apnea (OSA) is associated with many systemic diseases including diabetes, hypertension, stroke, and cardiovascular disease. The aim of our study was to investigate the association between OSA and optic neuropathy (ON), and to evaluate the efficacy of treatment for OSA on the risk of ON.

METHODS

We used the data from the Longitudinal Health Insurance Database, which involved one million insurants from Taiwan National Health Insurance program (Taiwan NHI).

RESULTS

OSA patients had a 1.95-fold higher risk of ON compared with non-OSA patients in all age group. The risk was significantly higher (adjusted hazard ratio: 4.21) in the group aged <45 years and male individuals (adjusted hazard ratio: 1.93). Meanwhile, sleep apnea was associated with ON regardless of the existence of comorbidity or not. OSA patients treated with continuous positive airway pressure (CPAP) had an adjusted 2.31-fold higher hazard of developing ON compared to controls, and those without any treatment had an adjusted 1.82-fold higher hazard of developing ON compared to controls. Moreover, ON patients had a 1.45-fold higher risk of OSA, and those aged between 45 and 64 years (hazard ratio: 1.76) and male individuals (hazard ratio: 1.55) had highest risk.

CONCLUSIONS

Our study showed that OSA increased the risk of developing ON after controlling the comorbidities; however, treatment with CPAP did not reduce the risk of ON. Further large population study accessing to medical records about the severity of OSA and treatment for OSA is needed to clarify the efficacy of treatment for OSA in reducing the risk of ON.

Prevalence and risk factors of eye diseases in adult patients with obstructive sleep apnoea: results from the SLE.E.P.Y cohort study

OBJECTIVES

To assess the occurrence of glaucoma, eyelid, corneal and macular disorders in a cohort of patients with obstructive sleep apnoea (OSA) diagnosed by overnight polysomnography and to investigate into the risk factors for the above eye diseases (EDs).

DESIGN

Cross-sectional cohort study between 2014 and 2015.

SETTING

Unit of Respiratory Medicine and Eye Clinic of the University of Verona.

PARTICIPANTS

431 consecutive patients were considered eligible. Of these, 87 declined to participate, 35 were untraceable and 13 were deceased.

INTERVENTIONS

A complete ophthalmic evaluation of both eyes for each patient.

PRIMARY AND SECONDARY OUTCOME MEASURES

Best-corrected distance visual acuity, intraocular pressure, corneal, macular and optic nerve optical coherence tomography, ocular aberrometry, optic nerve laser polarimetry, visual field test, and eyelid examination.

RESULTS

296 patients aged 64.5±12.8 years, 23% female and 77% male, underwent ophthalmic examination. There was 56% (n=166) prevalence of eyelid disorders, 27% (n=80) of corneal disorders, 13% (n=39) of macular disorders and 11% (n=33) of glaucoma. Advancing age was not associated with the severity of OSA, while significant differences were found for gender, body mass index, Oxygen Desaturation Index, smoking habit, hypertension and diabetes. Severe OSA was significantly associated with glaucoma (OR, 95% CI 1.05 to 5.93, p=0.037).

CONCLUSIONS

EDs were more prevalent in our patinets with OSA than in the general population. Severe Apnoea/Hypopnoea Index level seemed to play a role as risk factor only for glaucoma.

Longitudinal relationship between traumatic brain injury and the risk of incident optic neuropathy: A 10-year follow-up nationally representative Taiwan survey

Accumulating evidences had shown that traumatic brain injury was associated with visual impairment or vision loss. However, there were a limited number of empirical studies regarding the longitudinal relationship between traumatic brain injury and incident optic neuropathy. We studied a cohort from the Taiwanese National Health Insurance data comprising 553918 participants with traumatic brain injury and optic neuropathy-free in the case group and 1107836 individuals without traumatic brain injury in the control group from 1st January 2000. After the index date until the end of 2010, Cox proportional hazards analysis was used to compare the risk of incident optic neuropathy. During the follow-up period, case group was more likely to develop incident optic neuropathy (0.24%) than the control group (0.11%). Multivariate Cox regression analysis demonstrated that the case group had a 3-fold increased risk of optic neuropathy (HR = 3.017, 95% CI = 2.767-3.289, p < 0.001). After stratification by demographic information, traumatic brain injury remained a significant factor for incident optic neuropathy. Our study provided evidence of the increased risk of incident optic neuropathy after traumatic brain injury during a 10-year follow-up period. Patients with traumatic brain injury required periodic and thorough eye examinations for incident optic neuropathy to prevent potentially irreversible vision loss.

Visual Impairment among Older Adults in a Rural Community in Eastern China

Purpose. To determine the prevalence, causes, and associations of visual impairment (VI) among participants aged 60 years or older in a rural community in China. Methods. A community-based survey was undertaken in a rural town located in Eastern China and 4579 people aged 60 years or older participated in the study. Presenting visual acuity was assessed using a Snellen chart with tumbling-E optotypes and anterior segment was examined using a slit-lamp. VI was defined as presenting VA <6/18 and it included moderate VI (<6/18 to 6/60) and blindness (<6/60). Results. The prevalence of VI was 5.4% (95% confidence interval [CI] 4.7–6.0). In multivariate analysis, the presence of VI was positively associated with increasing age (odds ratio [OR] = 1.12, 95% CI 1.10–1.16, per year increase), female gender (OR = 2.33, 95% CI 1.53–3.55), the presence of hypertension (OR = 1.31, 95% CI 1.001–1.85), living alone (OR = 1.52, 95% CI 1.08–2.62), and increased sleeping hours (OR = 1.10, 95% CI 1.001–1.22). Drinking 3 or more glasses of green tea per day was inversely associated with VI (OR = 0.79, 95% CI 0.63–0.98). Conclusion. VI was less prevalent in this community compared with previous report in other areas in China.

Associations between obstructive sleep apnoea, primary open angle glaucoma and age-related macular degeneration: record linkage study

BACKGROUND

Primary open angle glaucoma (POAG) is thought to be associated with obstructive sleep apnoea (OSA) but previous studies are conflicting and have methodological limitations. This potential relationship has implications for investigation and treatment strategies, and may provide insights into disease pathogenesis. The relationship between OSA and age-related macular degeneration (AMD) is unknown.

METHODS

A sleep apnoea cohort of 67 786 people was constructed from linked English hospital episode statistics (1999-2011). We compared this cohort with a reference cohort (2 684 131 people) for rates of subsequent POAG and AMD. A POAG cohort (comprising 87 435 people) and an AMD cohort (248 408 people) were also constructed and compared with the reference cohort for rates of subsequent sleep apnoea. All analyses were restricted to people aged 55 and over and, within this age range, were age standardised using 5-year age groups.

RESULTS

Risk of POAG following sleep apnoea was not elevated: the rate ratio for POAG was 1.01 (95% CI 0.85 to 1.19). Similarly, the risk of sleep apnoea following POAG was not elevated: the rate ratio was 1.00 (0.86 to 1.17). These findings held true across subgroup analysis according to sex and age group. By contrast, the risk of AMD following sleep apnoea was significantly elevated, with rate ratio 1.44 (1.32 to 1.57).

CONCLUSIONS

Although plausible mechanisms exist to consider a link between OSA and POAG, the two conditions are not positively associated. This holds true in either temporal direction. By contrast, OSA is positively associated with AMD. While potential confounding factors may contribute, obesity does not appear sufficient to explain this association.

Glaucoma and its association with obstructive sleep apnea: A narrative review

Obstructive sleep apnea (OSA) is one of the systemic risk factors for glaucoma which causes irreversible visual field (VF) damage. We reviewed the published data of all types of studies on the association between these two conditions and papers regarding functional and structural changes related to glaucomatous damage using Scopus, web of science, and PubMed databases. There is evidence that the prevalence of glaucoma is higher in OSA patients, which independent of intraocular pressure (IOP). Studies have reported thinning of retinal nerve fiber layer (RNFL), alteration of optic nerve head, choroidal and macular thickness, and reduced VF sensitivity in patients of OSA with no history glaucoma. A negative correlation of apnea-hypopnea index with RNFL and VF indices has been described in some studies. Raised IOP was noted which is possibly related to obesity, supine position during sleep, and raised intracranial pressure. Diurnal fluctuations of IOP show more variations in OSA patients before and after continuous positive airway pressure (CPAP) therapy when compared with the normal cases. The vascular factors behind the pathogenesis include recurrent hypoxia with increased vascular resistance, oxidative stress damage to the optic nerve. In conclusion, comprehensive glaucoma evaluation should be recommended in patients with OSA and should also periodically monitor IOP during CPAP treatment which may trigger the progression of glaucomatous damage.

Optic Nerve Dysfunction in Obstructive Sleep Apnea: An Electrophysiological Study

STUDY OBJECTIVES

The aim of this study was to evaluate the integrity of the visual system in patients affected by obstructive sleep apnea (OSA) by means of electroretinogram (ERG) and visual evoked potential (VEP).

METHODS

We performed electrophysiological study of the visual system in a population of severe OSA (apnea-hypopnea events/time in bed ≥ 30/h) patients without medical comorbidities compared to a group of healthy controls similar for age, sex, and body mass index. Patients and controls did not have visual impairment or systemic disorders with known influence on the visual system. ERG and VEP were elicited by a reversal pattern generated on a television monitor at low (55') and high (15') spatial frequencies stimulation. Daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS) in both patients and controls.

RESULTS

In comparison with healthy controls (n = 27), patients with OSA (n = 27) showed a significant latency delay coupled with a significant amplitude reduction of P100 wave of VEP at all spatial frequencies in both eyes. No significant differences between groups were detected as concerning ERG components. No correlations were found between polygraphic parameters, ESS scores, or VEP and ERG components in OSA patients.

CONCLUSIONS

This study documented that patients with OSA, without medical comorbidities, present VEP alteration as documented by lower amplitude and longer latency of the P100 component than healthy controls. These altered electrophysiological findings may be the expression of optic nerve dysfunction provoked by hypoxia, acidosis, hypercarbia and airway obstruction, frequently observed in patients with OSA. Hence, we hypothesize that OSA per se may impair optic nerve function.

Effect of obstructive sleep apnea syndrome on corneal thickness

Obstructive sleep apnea syndrome (OSAS) might be a risk factor for the development of eye disorders. The aim of the study was to evaluate the effect of OSAS on central corneal thickness (CCT). A total of 195 patients were enrolled in the study, and underwent polysomnography. Patients were divided according to their apnea-hypopnea index (AHI) scores into control group (AHI < 5), mild (AHI, 5-15), moderate (AHI, 15-30), and severe OSAS (AHI > 30) groups. In ophthalmological examinations, CCT, auto refractometer measurement, tear break-up time, and Schrimer's test results were evaluated. Central corneal thickness was significantly decreased in patients with OSAS compared to the control group (542.14 ± 31.21 vs. 569.92 ± 13.46, p < 0.001). As the severity of OSAS increased, CCT decreased (mild OSAS = 567.48 ± 23 mm, moderate OSAS = 530.21 ± 30.2 mm, and severe OSAS = 557.97 ± 16.52 mm, respectively, p < 0.001). The mean values of auto refractometer, tear break-up time, and Schrimer's test were similar between the groups (p > 0.05). CCT was negatively correlated with AHI, oxygen desaturation index, desaturation percentages, and positively correlated with minimum oxygen saturation values (p < 0.05). This study showed that central corneal thickness is inversely correlated with the severity of OSAS. OSAS affects all organ systems particularly cardiovascular and neurological mechanisms. Further studies are warranted to evaluate the effect of OSAS treatment on CCT.