EVALUATİON OF THE EFFECT OF OBSTRUCTİVE SLEEP APNEA SYNDROME ON RETİNAL MİCROVASCULARİTY BY OPTİCAL COHERENCE TOMOGRAPHY ANGİOGRAPHY

Retinal microvascular phenotypes can track small vessel disease burden and CPAP treatment effectiveness in obstructive sleep apnea

Optical coherence tomography angiography (OCT-A) retinal imaging enables in vivo visualization of the retinal microvasculature that is developmentally related to the brain and can offer insight on cerebrovascular health. We investigated retinal phenotypes and neuroimaging markers of small vessel disease (SVD) in individuals with obstructive sleep apnoea (OSA). We enrolled 44 participants (mean age 50.1 ± SD 9.1 years) and performed OCT-A imaging before and after continuous positive airway pressure (CPAP) therapy. Pre-treatment analyses using a generalized estimating equations model adjusted for relevant covariates, revealed perivascular spaces (PVS) volume in basal ganglia associated with greater foveal vessel density (fVD) (p-value < 0.001), and smaller foveal avascular zone area (p-value = 0.01), whereas PVS count in centrum semiovale associated with lower retinal vessel radius (p-value = 0.02) and higher vessel tortuosity (p-value = 0.01). A reduction in retinal vessel radius was also observed with increased OSA severity (p-value = 0.05). Post-treatment analyses showed greater CPAP usage was associated with a decrease in fVD (p-value = 0.02), and increased retinal vessel radius (p-value = 0.01). The findings demonstrate for the first time the potential use of OCT-A to monitor CPAP treatment and its possible impact on both retinal and brain vascular health.

Retinal Vascular Density Change in Patients With Aortic Valve Regurgitation

BACKGROUND

The aim of this study was to assess retinal vessel density in the superficial capillary plexus layer, deep capillary plexus layer and choriocapillaris plexus layer in patients with aortic valve regurgitation (AR) using optical coherence tomography angiography (OCTA).

METHODS

Thirty-eight healthy participants (group 1) and 38 patients with AR (group 2) were assessed for this study. Diagnosis of AR is made by transthoracic echocardiography (TTE). Severity of AR was assessed according to values in the 2014 American Heart Association/American College of Cardiology (AHA/ACC) valve guideline. Superficial capillary plexus density (SCPD), deep capillary plexus density (DCPD) and choriocapillaris plexus density (CCPD) were analyzed between groups using OCTA.

RESULTS

SCPD measurements were found to be decreased in the nasal, inferior and central regions of patients with AR (P ≤ 0.05). DCPD measurements were found to be decreased in the nasal and inferior regions of patients with AR (P ≤ 0.05). CCPD measurements were found to be decreased in the inferior and central regions of patients with AR (P ≤ 0.05). In patients with AR, CCPD measurements were significantly decreased in the inferior region compared to the control group. Central macular thickness was found to be significantly decreased in the patients with AR.

CONCLUSIONS

Patients with AR showed decreased flow density compared with healthy controls. Retinal perfusion measured using OCTA in patients with AR may give an idea about microperfusion.

RETINAL VASCULAR DENSITY CHANGE IN PATIENTS WITH HEART FAILURE

PURPOSE

The aim of this study is to assess choroid thickness, retinal vessel density in the superficial capillary plexus layer and deep capillary plexus layer in heart failure (HF) using optical coherence tomography angiography (OCT-A).

METHODS

36 healthy participants (group 1), 33 patients with HF were assessed for this study. HF patients had a left ventricular ejection fraction (LVEF) <50%. HF patients were divided into 2 groups according to the New York Heart Association (NYHA). 15 patients were evaluated as group 2 according to NYHA and 18 patients as group 3 according to NYHA. Choroid thickness, superficial and deep capillary plexus perfusion were analyzed between groups using OCT-A.

RESULTS

Choroid thicknesses were found to be significantly decrease in the HF groups. Superficial capillary plexus density was compared with the control group, no statistically significant difference was found between the HF groups. But among the HF groups, a statistically significant decrease was found in group 3 patients. Deep capillary plexus density was compared with the control group, a statistically significant decrease was found in group 3. In addition, deep capillary plexus density a statistically significant difference was found between the groups HF.

CONCLUSIONS

Patients with HF showed decreased flow density compared with healthy controls. In addition, significant changes were found in flow densities among the HF groups. Retinal perfusion measured using OCT-A may give an idea about the hemodynamic status and microperfusion of HF patients.

Retinal vascular fractal dimension measurements in patients with obstructive sleep apnea syndrome: a retrospective case-control study

STUDY OBJECTIVES

We performed a case-control study to investigate the correlation between the apnea-hypopnea index (AHI) and the retinal vascular fractal dimension (FD).

METHODS

We selected 527 individuals who underwent polysomnography during health checkups at the Huadong Sanatorium from January to December 2021 as the study population, of whom 468 were included and 59 were excluded. All participants underwent a detailed health examination, including medical history assessment, physical examination, assessment of lifestyle factors, fundus photography, and laboratory examinations. The retinal vasculature was quantitatively assessed using Singapore I Vessel Assessment (SIVA) software. The relationship between the AHI and the retinal vessel quantitative was examined by multiple linear regression analyses and restricted cubic spline.

RESULTS

Among the 468 studied individuals, the average age was 51.51 (43-58) years, with 369 (78.85%) men and 99 (21.15%) women. According to the AHI indicator, 355 individuals were diagnosed with obstructive sleep apnea (OSA) syndrome, with an average AHI of 17.00 (9.200-30.130) events/h; 113 individuals were classified as controls, with an average AHI of 2.13 (0.88-3.63) events/h. In multiple linear regression, following varying degrees of adjustment for confounding factors, FD was reduced by 0.013 (P = .012; 95% confidence interval [CI]: -0.024 to -0.003), FD arteriole (FDa) was reduced by 0.013 (P = .019; 95% CI: -0.024 to -0.002), and FD venule (FDv) was reduced by 0.014 (P = .08; 95% CI: -0.024 to -0.004) in the high-AHI group compared with the low-AHI group. All tests for trend P values were < .05. The restricted cubic spline in the overall OSA population and the individuals without diabetes revealed a U-shaped pattern of decreasing, then increasing, FD, FDa, and FDv with a rising AHI. In the OSA individual with diabetes, FD, FDa, and FDv gradually decreased with increasing AHI.

CONCLUSIONS

The FD is associated with AHI in OSA individuals. The link between AHI and FD varied for OSA individuals with and without diabetes.

CITATION

Wang J, Chen T, Qi X, Li Y, Yang X, Meng X. Retinal vascular fractal dimension measurements in patients with obstructive sleep apnea syndrome: a retrospective case-control study. J Clin Sleep Med. 2023;19(3):479-490.

Diabetes mellitus associated neurovascular lesions in the retina and brain: A review

Diabetes mellitus (DM) is now recognized as a system-wide, autoimmune, inflammatory, microvascular disorder, which, in the retina and brain results in severe multifocal injury now recognized as a leading cause, world-wide, of progressive vision loss and dementia. To address this problem, resulting primarily from variations in glycemia in the prediabetic and overt diabetic states, it must be realized that, although some of the injury processes associated with diabetes may be system wide, there are varying responses, effector, and repair mechanisms that differ from organ to organ or within varying cell structures. Specifically, within the retina, and similarly within the brain cortex, lesions occur of the "neurovascular unit", comprised of focal microvascular occlusions, inflammatory endothelial and pericyte injury, with small vessel leakage resulting in injury to astrocytes, Müller cells, and microglia, all of which occur with progressive neuronal apoptosis. Such lesions are now recognized to occur before the first microaneurysms are visible to imaging by fundus cameras or before they result in detectable symptoms or signs recognizable to the patient or clinician. Treatments, therefore, which currently are not initiated within the retina until edema develops or there is progression of vascular lesions that define the current staging of retinopathy, and in the brain only after severe signs of cognitive failure. Treatments, therefore are applied relatively late with some reduction in progressive cellular injury but with resultant minimal vision or cognitive improvement. This review article will summarize the multiple inflammatory and remediation processes currently understood to occur in patients with diabetes as well as pre-diabetes and summarize as well the current limitations of methods for assessing the structural and functional alterations within the retina and brain. The goal is to attempt to define future screening, monitoring, and treatment directions that hopefully will prevent progressive injury as well as enable improved repair and attendant function.

Association of self-reported snoring with decreased retinal thickness and vessel density

Purpose: Self-reported snoring has been reported to influence nerves and vessels. However, there are few direct evidences of snoring related to nerves and microvessels defects. Therefore, we evaluated the association of self-reported snoring with retinal structure and microcirculation.

Methods: A total of 2,622 participants were recruited from the Jidong eye cohort study (JECS). Physical examinations, laboratory tests, and questionnaires were recorded. We also used optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) to assess the retinal structure and microvascular network. Snoring was defined as “never,” “occasionally,” and “frequently or more severe” according to self-reported frequency.

Results: The prevalence of snoring were 84.6% (n = 983) and 45.0% (n = 657) in males and females, respectively. Compared with never snoring group, the retinal thickness increased in “occasionally” (p &lt; 0.001) and “frequently or more severe” groups (p = 0.001), while no difference was found between snoring groups (p = 0.14). Superficial retinal capillary plexus (RCP) vessel density was lower in “frequently or more severe” group than in “never” (p &lt; 0.001) and “occasionally” snoring groups (p &lt; 0.001). After adjusting for confounders, “frequently or more severe” snoring was significantly associated with thinner total retinal thickness [β = −2.79 (95% CI: −5.27, −0.30)] and lower superficial RCP vessel density [β = −0.71 (95% CI: −1.19, −0.23)].

Conclusion: Our research showed self-reported snoring was associated with thinner retinal thickness and lower superficial RCP vessel density. The findings of our study emphasize the need for self-reported snoring assessments in determining retinal structure and microcirculation impairment.