Normal tension glaucoma in obstructive sleep apnea syndrome: A structural and functional study.

Area of Science:

• Ophthalmology
• Sleep Medicine
• Cardiovascular Research

Background:

• Normal tension glaucoma (NTG) is a form of glaucoma where intraocular pressure is not elevated.
• Obstructive sleep apnea syndrome (OSAS) is characterized by repeated episodes of upper airway collapse during sleep.
• The relationship between OSAS and NTG requires further investigation to understand underlying mechanisms.

Purpose of the Study:

• To investigate the association between obstructive sleep apnea syndrome (OSAS) and normal tension glaucoma (NTG).
• To evaluate functional and structural parameters in NTG patients with OSAS using standard automated perimetry (SAP) and optical coherence tomography angiography (OCTA).
• To identify OSAS as a potential risk factor for NTG and elucidate the role of vascular dysregulation.

Main Methods:

• Retrospective, cross-sectional study involving participants examined with polysomnography (PSG) and OCTA.
• Functional parameters (SAP) and structural parameters (peripapillary and macular vessel density [VD] via OCTA) were recorded.
• Participants were categorized into perimetric and nonperimetric groups based on SAP results, with OSAS severity graded by apnea-hypopnea index (AHI).

Main Results:

• Moderate/severe OSAS (AHI ≥ 15) was associated with longer neck circumference and shorter ocular axial length compared to mild OSAS.
• The NTG perimetric group exhibited significantly higher AHI and larger neck circumference than the control group.
• Reduced superficial and deep-layer peripapillary and macular VD were observed in the perimetric group, with negative correlations between visual field parameters and VD NH/VD RPC.

Conclusions:

• Obstructive sleep apnea syndrome (OSAS) is identified as a significant risk factor for normal tension glaucoma (NTG).
• Optical coherence tomography angiography (OCTA) findings, particularly whole-layer retinal capillary dropout, support the hypothesis that vascular dysregulation in OSAS contributes to NTG.
• These findings highlight the importance of considering OSAS in the management and understanding of NTG.