Peripapillary Vessel Density In Unilateral Preperimetric Glaucoma

Area of Science:

• Ophthalmology
• Medical Imaging
• Glaucoma Research

Background:

• Glaucoma is a progressive optic neuropathy often associated with elevated intraocular pressure.
• Preperimetric glaucoma (PPG) represents an early stage where visual field loss is not yet detectable.
• Assessing microvascular changes in early glaucoma is crucial for understanding disease progression.

Purpose of the Study:

• To investigate vessel density (VD) of radial peripapillary capillaries (RPC) and structural alterations in patients with unilateral PPG using optical coherence tomography angiography (OCTA).
• To compare vascular and structural parameters between PPG eyes, their fellow eyes, and healthy controls.

Main Methods:

• A cross-sectional observational study involving 13 untreated patients with unilateral PPG.
• Measurement of RPC VD (optic disc, peripapillary, and whole image areas) and retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thickness using spectral-domain OCT/OCTA.
• Comparison of parameters between PPG eyes, fellow eyes (F), and 20 healthy eyes (H).

Main Results:

• PPG eyes exhibited significantly lower peripapillary and whole image RPC VD compared to fellow eyes (p<0.001).
• Both PPG and fellow eyes showed significantly thinner RNFL and GCC compared to healthy eyes (p<0.001).
• Area under the curve analysis indicated excellent diagnostic ability for both structural and vascular parameters in differentiating PPG from healthy eyes, but only structural parameters were effective in differentiating fellow eyes from healthy eyes.

Conclusions:

• Unilateral PPG eyes demonstrate significant RPC dropout, suggesting microvascular dysfunction as an early event.
• Clinically unaffected fellow eyes have structural thinning but no significant microvasculature differences compared to healthy eyes.
• OCTA is a valuable tool for early glaucoma diagnosis, though peripapillary vascular parameters are not superior to structural measurements for differentiating early disease stages.