Citation:
Wang YH, Zhang P, Chen L, Jiang Z, Li LX, He K, Li XQ. Correlation between
obstructive sleep apnea and central retinal vein occlusion. Int J Ophthalmol 2019;12(10):1634-1636
DOI:10.18240/ijo.2019.10.17
·Brief
Report·
Correlation
between obstructive sleep apnea and central retinal vein occlusion
Yan-Hui Wang1, Peng Zhang2, Lian
Chen2, Zhao Jiang2, Lu-Xi Li2, Ke He2,
Xiao-Qing Li2
1Department of Otolaryngology, Xi’an
No.3 Hospital, the Affiliated Hospital of Northwest University, Xi’an 710018,
Shaanxi Province, China
2Department of Ophthalmology, Xi’an
No.3 Hospital, the Affiliated Hospital of Northwest University, Xi’an 710018,
Shaanxi Province, China
Correspondence to: Peng Zhang. Department of
Ophthalmology, Xi’an No.3 Hospital, the Affiliated Hospital of Northwest
University, the Third Fengcheng Road, Xi’an 710018, Shaanxi Province, China.
zhangpengfmmu@163.com
Received:
Abstract
To investigate the possible
correlation between obstructive sleep apnea (OSA) and central retinal vein
occlusion (CRVO). Thirty consecutive patients with a recent (<3mo) CRVO and
an age- and sex-matched group of 30 control subjects were recruited. All
subjects underwent full-night polysomnography to measure apnea-hypopnea index
(AHI) and oxygen desaturation index (ODI). The average AHI and ODI were
significantly higher in CRVO patients (AHI: 13.86±8.63, ODI: 9.21±4.47) than in
control subjects (AHI: 8.51±6.36, ODI: 5.87±3.18; P=0.008 and 0.001
respectively). Additionally, the AHI was positively correlated with body mass
index (BMI; r=0.476, P=0.017) and ODI (r=0.921, P<0.01)
in both CRVO and control subjects. According to AHI scores, twenty-two (73.33%)
CRVO patients had OSA and 12 (40.00%) control subjects had OSA, a difference
that was statistically significant (P=0.019). OSA may be a risk factor
for or a trigger of CRVO development.
KEYWORDS: central retinal vein occlusion;
obstructive sleep apnea; polysomnography; apnea-hypopnea index; oxygen
desaturation index
DOI:10.18240/ijo.2019.10.17
Citation:
Wang YH, Zhang P, Chen L, Jiang Z, Li LX, He K, Li XQ. Correlation between
obstructive sleep apnea and central retinal vein occlusion. Int J Ophthalmol 2019;12(10):1634-1636
Introduction
Central retinal vein occlusion
(CRVO) is a common retinal vascular disorder that generally occurs in adults
and can severely affect vision[1]. Histological
studies have shown that thrombus formation within the central retinal vein
lumen near the lamina cribrosa is the main cause of CRVO[1].
Thrombosis within a retinal vein leads to an increase in venous blood flow
resistance, which causes circulatory stasis and a marked rise in retinal venous
and capillary pressure[2].
Obstructive sleep apnea (OSA) is a
common sleep-related breathing disorder and is characterized by repeated
episodes of upper airway obstruction that result in apnea (breathing pause)
and/or hypopnea (airflow reduction) during sleep[3-4]. The subsequent reduction in alveolar ventilation
causes a decrease in oxygen saturation and, potentially, an increase in carbon
dioxide partial pressure, which may induce hypoxemia, hypercapnia and/or
increased sympathetic activity[5]. The occurrence
of OSA has been associated with several systemic diseases, including atherosclerosis,
hypertension, diabetes mellitus, and stroke. These conditions are also risk
factors for CRVO[2].
The current study prospectively
examined OSA prevalence in subjects with and without CRVO and specifically
assessed whether or not OSA is a risk factor for CRVO.
SUBJECTS AND METHODS
Ethical Approval This study followed tenets of the
Declaration of Helsinki, with approval from the Ethics Committee at Xi’an No.3
Hospital. Informed consent was obtained from all subjects.
Subjects Patients with a recent (<3mo)
CRVO were considered for study enrollment at Xi’an No.3 Hospital (Xi’an, China)
between January 2017 and December 2018. Research volunteers without CRVO were
also enrolled as a control group. Control subjects were age- and gender-matched
by random sampling. Subjects with diabetes mellitus, stroke, coronary artery
disease or other comorbidities reported to be associated with OSA were
excluded, with the exception of subjects with well-controlled hypertension.
Methods The presence of a CRVO was confirmed
by a retinal specialist with indirect ophthalmoscopy and fluorescein
angiography (FA). Logarithm of the minimum angle of resolution (logMAR)
best-corrected visual acuity (BCVA), intraocular pressure, and body mass index (BMI)
were measured in all included subjects. All subjects underwent polysomnography
using a commercially-available, portable sleep monitor (Somté, Compumedics,
Abbotsford, Australia). Sleep testing began at 23:00 and ended at 06:30. The
apnea-hypopnea index (AHI), oxygen desaturation index (ODI) were recorded and
compared.
The OSA severity was classified
using the AHI score, which represents the number of apnea and hypopnea events
per hour of sleep, into the following categories: normal (AHI<5), mild (5≤AHI≤14),
moderate (15≤AHI≤30), and severe (AHI>30)[6].
Statistical analyses were conducted
using SPSS statistical software (version20.0; SPSS Inc., Chicago, IL, USA). All
data are presented as mean±standard deviation or n (%) as applicable.
Comparisons between CRVO and control subjects were made using Pearson’s
Chi-square tests for categorical variables and independent Student’s t-tests
for continuous variables. Pearson’s correlation analysis was also performed to
assess relationships between CRVO and the presence of OSA. Statistical
significance was defined as P<0.05.
Results
This study included 30 subjects with
CRVO and 30 age- and gender-matched controls. Average age of CRVO patients was
52.51±11.72y (range, 35 to 70y); the average age of control subjects was
50.79±12.43y (range, 36 to 71y). The demographic and polysomnographic data for
CRVO group and controls are presented in Table 1. There were no statistical
differences in age, sex, intraocular pressure and hypertension history between
CRVO patients and control subjects. The differences of logMAR BCVA, BMI, AHI
and ODI were statistically significant between CRVO patients and control
subjects.
Table 1 Demographic characteristics
and polysomnographic data for patients with central retinal vein occlusion and
control subjects
mean±SD
|
Variables |
CRVO group |
Control group |
P |
|
Subjects (n) |
30 |
30 |
- |
|
Age (y) |
52.51±11.72 |
50.79±12.43 |
0.583 |
|
Sex (female/male) |
12/18 |
11/19 |
0.792 |
|
IOP (mm Hg) |
14.42±5.71 |
15.17±5.02 |
0.591 |
|
HTN (yes/no) |
13/17 |
10/20 |
0.595 |
|
BCVA, logMAR |
0.45±0.47 |
0.72±0.53 |
0.041 |
|
BMI |
26.87±4.45 |
24.64±3.46 |
0.033 |
|
AHI |
13.86±8.63 |
8.51±6.36 |
0.008 |
|
ODI |
9.21±4.47 |
5.87±3.18 |
0.001 |
CRVO: Central retinal vein
occlusion; HTN: Hypertension; BCVA: Best-corrected visual acuity; logMAR:
Logarithm of the minimum angle of resolution; IOP: Intraocular pressure; BMI:
Body mass index; AHI: Apnea-hypopnea index; ODI: Oxygen desaturation index.
For all patients, AHI showed a
positive correlation with BMI (r=0.476, P=0.017) and ODI (r=0.921,
P<0.001). However, AHI had no significant correlation with age, IOP
and logMAR BCVA. According to AHI score, 22 (73.33%) of 30 with CRVO patients
had OSA; 12 (40.00%) of 30 control subjects had OSA. The prevalence of OSA was
statistically different between CRVO patients and control subjects. Table 2
shows the comparison of OSA severity in CRVO patients and in control subjects.
Table 2 Comparison of obstructive
sleep apnea in patients with central retinal vein occlusion and in control
subjects n (%)
|
OSA |
CRVO group (n=30) |
Control group (n=30) |
P |
|
Total |
22 (73.33) |
12 (40.00) |
0.019 |
|
Mild |
8 (26.67) |
4 (13.33) |
0.333 |
|
Moderate |
9 (30.00) |
6 (20.00) |
0.551 |
|
Severe |
5 (16.67) |
2 (6.67) |
0.421 |
CRVO: Central retinal vein
occlusion; OSA: Obstructive sleep apnea.
Discussion
The prevalence of OSA is
approximately 4.8% in the Asian population, its incidence is expected to rise
in an aging and obesity population[7]. OSA are
usually insidious during sleep and most patients are unaware of experiencing
OSA symptoms[5]. Polysomnography is a
multi-parametric test used in the study of sleep and as a diagnostic tool in
sleep medicine. According to AHI and oxygen desaturation levels recorded by
overnight polysomnography monitoring, the severity of obstructive sleep apnea
can be defined[8].
This study indicated that AHI and
ODI scores were significantly higher in the CRVO patients (AHI: 13.86±8.63,
ODI: 9.21±4.47) than in the control subjects (AHI: 8.51±6.36, ODI: 5.87±3.18; P=0.008
and 0.001 respectively). Correspondingly, the prevalence of OSA were
significantly higher in CRVO patients (73.33%) than in control subjects
(40.00%; P=0.019). Therefore, OSA may be a risk factor for CRVO
development.
OSA is characterized by a marked
sympathetic overdrive, which triggers cerebral blood flow velocity dramatically
and oxygen saturation decrease[9]. These changes
may increase intracranial pressure and venous pressure on the optic papillary,
mechanically impeding retinal blood flow, reducing spontaneous venous
pulsation, leading to an increase in retinal venous pressure[9-10].
AHI was correlated with the BMI,
which corroborates the known association between OSA severity and excess body
weight[11]. This study also confirmed this
correlation in both CRVO and control subjects. Clinical observations have
proven that excess weight is a well-established predictor of sleep-disordered
breathing (SDB)[11]. Age and excess weight are
also known as risk factors of diabetes mellitus, hypertension, and
arteriosclerosis, which have been reported to be associated with CRVO[12]. Therefore, weight loss may benefit not only on OSA
severity but also in mitigating systemic diseases related to both OSA and
obesity.
Intermittent nocturnal hypoxemia is
another characteristic of OSA[6]. The ODI can
reflect intermittent nocturnal hypoxemia severity. Intermittent nocturnal hypoxia
may increase systemic oxidative stress and produce reactive oxygen species and
inflammatory cytokines, such as interleukin 1 (IL-1) and interleukin 6 (IL-6),
which may activate the extrinsic coagulation pathway and subsequent venous
thrombosis in OSA patients and trigger CRVO development[13-15].
Based on the high prevalence of OSA
in CRVO patients in this study, we believe that OSA could be a risk factor for
occurance of CRVO. In addition, OSA may function as a triggering factor for
patients of CRVO with predisposing conditions, such as hypertension, diabetes
mellitus, atherosclerosis[1]. We should pay
attention to the role of OSA involving in pathogenesis of CRVO, and we suggest
that diagnostic polysomnography should be considered as an appropriate adjunct
for each CRVO patients other than diagnostic imaging of retina.
The main limitation of this study
was its small sample size. Further studies are needed on a larger group of
patients to confirm the high OSA incidence in CRVO patients and to understand
if OSA treatment can influence CRVO development and/or regression.
ACKNOWLEDGEMENTS
Foundation: Supported by Planned Science and
Technology Project of Xi’an City, China [No.2017116SF/YX010(9)].
Conflicts of Interest: Wang YH, None; Zhang P, None; Chen
L, None; Jiang Z, None; Li LX, None; He K, None; Li
XQ, None.
References