A study published in Medicina investigated the impact of obstructive sleep apnea syndrome (OSAS) on macular vascular density (VD) and perfusion density (PD).
Give me some background first.
OSAS is a growing health issue where the pharynx collapses during sleep, which has been associated with increased risks pertaining to diabetes and cardiovascular events.
In addition, some studies have found associations between OSAS and ophthalmic conditions such as:
- Non-arteritic anterior ischemic optic neuropathy
- Retinal vein occlusion
- Glaucoma
- Diabetic macular edema (DME)
Go on...
With some inconsistent findings regarding the impact of OSAS on the retinal vascular network, researchers set out to investigate utilizing optical coherence tomography angiography (OCTA).
Who was included in the study?
Recruitment for participants was through the Sleep Laboratory of Erasme Hospital (SLEH) in Brussels, Belgium, where each participant had a previously indicated polysomnography from their physicians.
Patients were assessed from January to March 2021, and stayed at the SLEH for this duration. Polysomnographic examination and the following results were used to form control and study groups.
Tell me more.
Participants' obstructive apnea-hypopnea index (OAHI) was recorded and those with an OAHI of ≥5 were assigned to the OSAS group and those with levels <5 were assigned to the control group.
A total of 61 patients were divided into these two groups, with one eye from each patient observed.
- OSAS group: 49 participants
- Control group: 12 participants
What were the outcome measures?
The study observed the following from each participant:
- Refraction (SE)
- Best-corrected visual acuity (BCVA)
- Intraocular pressure (IOP) by pulsed air
- Macular thickness
- Choroidal thickness in the foveolar area
- Macular vascular density (VD) and perfusion density (PD)
All measurements were calculated in the superficial retinal capillary plexus (SCP), the deep retinal capillary plexus (DCP), and the retinal vascular network (RVN).
Findings?
There were significant differences in the VD and PD of the DCP in the perifoveolar area in the OSAS group compared with those in the control group.
The VD of the DCP in the parafoveal area also increased significantly in the OSAS group and no significant differences between the groups were found in the SVP and RVN.
Expert opinion?
Per the authors of the study: “This study revealed an increase in the VD of the DCP in the (parafoveal) and (perifoveal) areas and PD of the DCP in the (perifoveal) area in patients with newly diagnosed OSAS.”
They continued to maintain that this “suggests that collateral vessel formation and possible retinal vasodilation occur in the DCP for this particular subpopulation.”
Limitations?
The authors spoke to how this study was limited to a single center and by the number of participants enrolled.
They also mentioned a more limited generalizability due to only the inclusion of patients who agreed to participate out of those invited.
Take home.
“The identification of these alterations in macular VD and PD related to OSAS could allow the future development of new strategies for the prevention and treatment of ophthalmological complications in patients with OSAS,” the authors stated.
Ultimately, they concluded: “Studies with long-term follow-up seem to be necessary to explore and confirm the hypothesis of a two-phase pathophysiological mechanism that could explain our results and those of previous studies on older patients with OSAS.”