Continuous intraocular pressure monitoring in patients with obstructive sleep apnea syndrome using a contact lens sensor

Ocular Inflammation and Oxidative Stress as a Result of Chronic Intermittent Hypoxia: A Rat Model of Sleep Apnea

Obstructive sleep apnea (OSA) is a sleep disorder characterized by intermittent complete or partial occlusion of the airway. Despite a recognized association between OSA and glaucoma, the nature of the underlying link remains unclear. In this study, we investigated whether mild OSA induces morphological, inflammatory, and metabolic changes in the retina resembling those seen in glaucoma using a rat model of OSA known as chronic intermittent hypoxia (CIH). Rats were randomly assigned to either normoxic or CIH groups. The CIH group was exposed to periodic hypoxia during its sleep phase with oxygen reduction from 21% to 10% and reoxygenation in 6 min cycles over 8 h/day. The eyes were subsequently enucleated, and then the retinas were evaluated for retinal ganglion cell number, oxidative stress, inflammatory markers, metabolic changes, and hypoxic response modulation using immunohistochemistry, multiplex assays, and capillary electrophoresis. Statistically significant differences were observed between normoxic and CIH groups for oxidative stress and inflammation, with CIH resulting in increased HIF-1α protein levels, higher oxidative stress marker 8-OHdG, and increased TNF-α. Pyruvate dehydrogenase kinase-1 protein was significantly reduced with CIH. No significant differences were found in retinal ganglion cell number. Our findings suggest that CIH induces oxidative stress, inflammation, and upregulation of HIF-1α in the retina, akin to early-stage glaucoma.

Impact of positive airway pressure therapy on intraocular pressure in obstructive sleep apnea: A systematic review

BACKGROUND

Positive airway pressure (PAP) therapy has been reported to have variable effect on intraocular pressure (IOP) in patients with obstructive sleep apnea (OSA) . The objective of this review is to present a qualitative assessment of available literature on impact of PAP on IOP in patients of OSA.Method: Online databases were searched for relevant articles up to September 2023. It included randomized control trial (RCT), prospective observational study, case control study, cross-sectional study, published abstract having relevant information. The comparator group consisted of OSA patients not receiving the PAP therapy or the pre-PAP IOP. Studies reporting change in IOP immediately after PAP use, at 1 month and at 1 year of PAP use were included. For quality assessment Cochrane Risk of Bias tool version 2 and NIH study quality assessment tool for Before-After (Pre-Post) Studies with No Control Group was used.Result: In this systematic review of ten clinical studies with 191 patients of OSA, use of continuous positive airway pressure (CPAP) therapy led to an immediate increase in IOP but it was not significantly different from non-CPAP users. One month and 1 year of CPAP use led to a significant increase in IOP from the baseline value.

CONCLUSION

The available albeit limited evidence suggests that CPAP use, particularly at higher pressures, is linked to an elevation in IOP. However, high quality evidence from well-designed RCTs is needed to confirm or refute this findings.

[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.

Advancements in Wearable and Implantable Intraocular Pressure Biosensors for Ophthalmology: A Comprehensive Review

Glaucoma, marked by its intricate association with intraocular pressure (IOP), stands as a predominant cause of non-reversible vision loss. In this review, the physiological relevance of IOP is detailed, alongside its potential pathological consequences. The review further delves into innovative engineering solutions for IOP monitoring, highlighting the latest advancements in wearable and implantable sensors and their potential in enhancing glaucoma management. These technological innovations are interwoven with clinical practice, underscoring their real-world applications, patient-centered strategies, and the prospects for future development in IOP control. By synthesizing theoretical concepts, technological innovations, and practical clinical insights, this review contributes a cohesive and comprehensive perspective on the IOP biosensor's role in glaucoma, serving as a reference for ophthalmological researchers, clinicians, and professionals.

Obstructive sleep apnoea and glaucoma: a systematic review and meta-analysis

INTRODUCTION

Obstructive sleep apnoea (OSA) has been thought to be associated with glaucoma, however there are many conflicting studies on this topic. With many new studies having been published since the previous meta-analysis, we believe it is important to clarify this association. Hence, in this study we meta-analyse the recent literature regarding the association between OSA and glaucoma.

METHODS

Pubmed, Embase, Scopus and Cochrane Library were searched from inception till the 28th February 2022 for observational as well as cross-sectional studies examining the association between OSA and glaucoma. Two reviewers selected studies, extracted data, graded the quality of included non-randomized studies using the Newcastle-Ottawa scale. The overall quality of evidence was assessed using GRADE. Random-effects models were used to meta-analyse the maximally covariate- adjusted associations.

RESULTS

48 studies were included in our systematic review, with 46 suitable for meta-analysis. Total study population was 4,566,984 patients. OSA was associated with a higher risk of glaucoma (OR 3.66, 95% CI 1.70 to 7.90, I2 = 98%, p < 0.01). After adjustment for various important confounders including age, gender and patient comorbidities such as hyperlipidaemia, hypertension, cardiovascular diseases and diabetes, patients with OSA had up to 40% higher odds of glaucoma. Substantial heterogeneity was eliminated through subgroup and sensitivity analyses after consideration of glaucoma subtype, OSA severity and adjustment for confounders.

CONCLUSIONS

In this meta-analysis, OSA was associated with higher risk of glaucoma, as well as more severe ocular findings characteristic of the glaucomatous disease process. We suggest more clinical studies looking into the effects of OSA treatment on the progression of glaucoma to help clinical decision making for patients.

Effects of continuous positive air pressure on intraocular pressure in patients with obstructive sleep apnea during the split-night study: An open-label randomized controlled trial

BACKGROUND

Intraocular pressure (IOP) is known to increase at midnight, when continuous positive airway pressure (CPAP) is initiated in split-night CPAP titration (SN-CPAP titration), in patients with obstructive sleep apnea (OSA); therefore, possible excessive increase in the IOP should be investigated. However, related studies on this topic are scarce. OSA causes increases and decreases in the IOP; however, its fluctuation during sleep remains unclear. Therefore, we determined the timing of these fluctuations in the IOP during sleep at night.

METHODS

This study included 25 patients with OSA. A 7-hour period of night sleep was divided into first (Sleep-1) and second halves (Sleep-2). Patients were randomly divided into the SN (natural breathing during Sleep-1, CPAP applied during Sleep-2) and C (without CPAP) groups. IOP was measured using the iCare Pro before Sleep-1 and after Sleep-1 and Sleep-2. The main hypothesis was that IOP would be significantly higher in the SN group than in the C group. The sub-hypothesis was that the effects of OSA on IOP are manifested at different times. The correlation is shown as Pearson's r for normally distributed data or Spearman's rho for non-normally distributed data. The difference between the SN and C groups in the time course of IOP during the night's sleep was analyzed using repeated-measures analysis of variance. A P value of <.05 was considered significant.

RESULTS

No significant difference was found in IOP between the groups, but the SN group showed a significantly increased IOP during Sleep-2 (post hoc Bonferroni test). The apnea-hypopnea index inversely correlated with IOP changes in Sleep-1 and positively correlated with those in Sleep-2.

CONCLUSION

This study does not support our main hypothesis that SN-CPAP titration promotes the effect of CPAP in increasing IOP. However, an expected range of the effect of increased CPAP on IOP has also been suggested. IOP-lowering and IOP-raising effects were predominant in the first and second halves of sleep in OSA, thereby providing a new perspective on measured IOP and supporting the subhypothesis.

Primary open-angle glaucoma in patients with obstructive sleep apnoea in a Colombian population: a cross-sectional study

OBJECTIVE

Determine the prevalence, functional and structural alterations of primary open-angle glaucoma (POAG) in patients with obstructive sleep apnoea (OSA).

DESIGN

Cross-sectional.

SETTING

Tertiary hospital associated with specialised center in ophthalmologic images in Bogota, Colombia.

PARTICIPANTS

150 patients, for a sample of 300 eyes, 64 women (42.7%) and 84 men (57.3%) between 40 and 91 years old with a mean age of 66.8 (±12.1) years.

INTERVENTIONS

Visual acuity, biomicroscopy, intraocular pressure, indirect gonioscopy and direct ophthalmoscopy. Patients classified as glaucoma suspects underwent automated perimetry (AP) and optical coherence tomography of the optic nerve OUTCOME MEASURE: The primary outcomes are the determination of prevalence of glaucoma suspects and POAG in patients with OSA. Secondary outcomes are the description of functional and structural alterations in computerised exams of patients with OSA.

RESULTS

The prevalence of glaucoma suspect was 12.6%, and for POAG was 17.3%. No alterations in the appearance of the optic nerve was seen in 74.6%, focal or diffuse thinning of the neuroretinal rim (16.6%) was the most frequently finding, followed by asymmetry of the disc>0.2 mm (8.6%) (p=0.005). In the AP, 41% showed arcuate, nasal step and paracentral focal defects. The mean retinal nerve fiber layer (RNFL) was normal (>80 µM) in 74% of the mild OSA group, 93.8% of the moderate group and 17.1% of the severe group. Similarly, normal (P5-90) ganglion cell complex (GCC) in 60%, 68% and 75%, respectively. Abnormal results in the mean RNFL was seen in 25.9%, 6.3% and 23.4% of the mild, moderate and severe groups, respectively. In the GCC, 39.7%, 33.3% and 25% of the patients in the aforementioned groups.

CONCLUSION

It was possible to determine the relationship between structural changes in the optic nerve and the severity of OSA. No relationship with any of the other studied variables was identified.

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.

Review of glaucoma medication adherence monitoring in the digital health era

Current glaucoma treatments aim to lower intraocular pressure, often with topical ocular hypotensive medications. Unfortunately, the effectiveness of these medications depends on sustained patient adherence to regimens which may involve instilling multiple medications several times daily. Patient adherence to glaucoma medications is often low. Recent innovations in digital sensor technologies have been leveraged to confirm eyedrop medication usage in real-time and relay this information back to providers. Some sensors have also been designed to deliver medication reminders and notifications as well as assist with correct eyedrop administration technique. Here, we review recent innovations targeted at improving glaucoma medication adherence and discuss their limitations.

Evaluation of Eyelid, Angle, and Anterior Segment Parameters Using Scheimpflug Camera and Topography System in Obstructive Sleep Apnea Syndrome

Objectives

The purpose of the study was to investigate the eyelid hyperlaxity, anterior segment, and corneal topographic parameters in patients with obstructive sleep apnea syndrome (OSAS) using Scheimpflug camera and topography system.

Methods

In this prospective and cross-sectional clinical study, 32 eyes of 32 patients with OSAS and thirty-two eyes of 32 healthy subjects were evaluated. The participants with OSAS were selected from those with an apnea-hypopnea index ≥ 15. The minimum corneal thickness (ThkMin), apical corneal thickness (ACT), central corneal thickness (CCT), pupillary diameter (PD), aqueous depth (AD), aqueous volume (AV), anterior chamber angle (ACA), horizontal anterior chamber diameter (HACD), corneal volume (CV), simulated K readings (sim-K), front and back corneal keratometric values at 3 mm, RMS/A values, highest point of ectasia on the anterior and posterior corneal surface (KVf, KVb), symmetry indices and keratoconus measurements were taken by combined Scheimpflug-Placido corneal topography and compared with healthy subjects. Upper eyelid hyperlaxity (UEH) and floppy eyelid syndrome were also evaluated.

Results

There were no statistically significant difference between groups in terms of age, gender, PD, ACT, CV, HACD, simK readings, front and back keratometric values, RMS/A-KVf and KVb values, symmetry indices, and keratoconus measurements (p>0.05). ThkMin, CCT, AD, AV, and ACA values were significantly higher in OSAS group compared to the control (p<0.05). UEH was detected in two cases in the control group (6.3%) and in 13 cases in the OSAS group (40.6%) and the difference was significant (p<0.001).

Conclusion

The anterior chamber depth, ACA, AV, CCT, and UEH increase in OSAS. These ocular morphological changes occurring in OSAS may explain why these patients prones to normotensive glaucoma.

A Narrative Review of the Association between Obstructive Sleep Apnea and Glaucoma in Adults

BACKGROUND

Obstructive sleep apnea (OSA) is a sleep disorder, primarily of the upper airway, which not only has a significant impact on quality of life but is also associated with various systemic diseases. Several ophthalmological diseases are also associated with OSA, especially glaucoma. The purpose of this review is to take a closer look at the causality and mutual influence.

METHODS

A systematic literature search was conducted using PubMed. A total of 19 studies with 316,178 adult participants were included.

RESULTS

Eleven of the sixteen studies concentrating on the prevalence of glaucoma in patients with OSA showed an association of both entities. One paper found a higher risk for progression of glaucoma in OSA patients. Five of the sixteen included studies failed to show a correlation between OSA and glaucoma. One study out of three surveying specific ophthalmological parameters showed an influence of OSA therapy on retinal nerve fiber layer (RNFL) thinning and vision. One study showed a rise in intraocular pressure (IOP), while two other studies showed no increase under continuous positive airway pressure (CPAP).

CONCLUSIONS

Our findings suggest an association between OSA and glaucoma and, especially, between OSA and thinning of RNFL. CPAP therapy appears to be also suitable for patients with comorbid glaucoma.

Effect of CPAP Therapy on 24-Hour Intraocular Pressure-Related Pattern From Contact Lens Sensors in Obstructive Sleep Apnea Syndrome

Purpose

To evaluate the effect of continuous positive airway pressure (CPAP) therapy on 24-hour intraocular pressure (IOP)-related pattern from contact lens sensors (CLS) in obstructive sleep apnea syndrome (OSAS).

Methods

Prospective, observational, case series study. Twenty-two eyes of 22 newly diagnosed patients with severe OSAS were included. A first 24-hour CLS measurement was performed before CPAP therapy was started, and a second 24-hour CLS monitoring was performed after beginning CPAP. We analyzed the amplitude and the maximum and minimum IOP-related values (m Veq). We also analyzed IOP-related measurements at five-minute intervals throughout the first hour of nocturnal acrophase, starting from when the patient fell asleep.

Results

The baseline measurements showed significant fluctuations in the IOP, with the highest IOP readings being recorded at night (nocturnal acrophase) in 17 of 22 patients (77.27%). Nocturnal acrophase began when the patients laid down to sleep. During CPAP therapy, the patients showed a more marked increase in IOP in the initial phase of nocturnal acrophase, with significant differences at 20, 25, 30, and 55 minutes (P < 0.05).

Conclusions

Most of patients with severe OSAS exhibited a nocturnal acrophase and the highest IOP readings at night. CPAP was associated with additional increase in IOP-related pattern for at least the first hour of CPAP use.

Translational Relevance

Our results suggest that CPAP was associated with additional increase in IOP during the initial phase of nocturnal acrophase. This effect could be important in the management of patients with OSAS and glaucomatous progression.