Findings from a study recently published in the Journal of Ophthalmology assessed optic nerve head (ONH) vascular changes in patients with obstructive sleep apnea-hypopnea syndrome (OSAS) via optical coherence tomography angiography (OCTA).
Give me some background.
OSAS is a respiratory sleep-related illness characterized by repetitive partial or complete upper airway obstruction during sleep that results in recurrent hypoxia and fragmented sleep.
For patients with OSAS: Recurrent apnea can lead to transient hypoxemia and increased vessel resistance, which contributes to ONH hypoperfusion and poor blood flow.
OCTA, on the other hand, is a helpful tool for quantifying peripapillary vessel density (VD) and other blood flow changes within the retinal microvascular network.
Note: Vessel density refers to the proportion of vessel area with blood flow over the total measured area—which in this case was a 6x6-mm OCTA scan.
Talk about the study.
In this meta-analysis, investigators searched four databases from inception to August 2023 for studies on ONH VD in eyes with OSAS vs. controls.
While an initial 134 studies were identified, they ultimately included six studies containing 479 eyes (333 in the OSAS group and 146 in the control group) in the final analysis.
Findings?
The radial peripapillary capillary (RPC) whole en face VD in the mild-to-moderate and severe OSAS groups was significantly lower compared to the controls (mean difference [MD] -0.96, P=0.03; MD=-1.42, P=0.001, respectively).
Note: The mean difference is the absolute difference between the mean value in two groups—clinical trials typically use this calculation to compare the averages of the experimental and control groups.
Anything else?
For RPC peripapillary VD, patients with mild-to-moderate OSAS demonstrated a trending decrease compared to controls (MD=-1.71, P=0.05).
There was also a significant difference in RPC peripapillary VD between eyes with severe OSAS and controls (MD=-3.08, P=0.004).
In addition, the RPC inside disc VD was reduced in severe OSAS eyes than in the controls (MD=-0.07, P=0.94).
Limitations?
Key limitations included the relatively small sample sizes utilized in the study and the high heterogeneity among the six trials that may have impacted the reliability of findings.
Take home.
Ultimately: These findings suggest that peripapillary vascular density was reduced in patients with OSAS.
As such, the study authors noted that ONH VD measured via OCTA could be a potential biomarker for diagnosing and monitoring the severity of OSAS in patients.