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Updated: Aug 23, 2025
Assessing Early Stage Open-Angle Glaucoma in Patients by Isolated-Check Visual Evoked Potential
Published on: May 25, 2020
Birefringent Properties of the Peripapillary Retinal Nerve Fiber Layer in Healthy and Glaucoma Subjects Analyzed by
Stefan Steiner1, Florian Schwarzhans2, Sylvia Desissaire3
1Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria.
Purpose:
To study the circumpapillary retinal nerve fiber layer (RNFL) birefringence (BIR) of early glaucoma and age-matched healthy eyes using polarization-sensitive optical coherence tomography (PS-OCT).
Methods:
In this prospective cross-sectional study, we compared virtual circular PS-OCT B-scans with a diameter of 3.5 mm centered on the optic disc (OD) acquired with a PS-OCT prototype (860 nm center wavelength). Early glaucoma was defined by the glaucomatous appearance of the OD and a pathologic visual field test with a mean deviation (MD) better than -6 dB. The main outcome parameters were BIR, RNFL-thickness (RNFL-T), and phase retardation (RET). The BIR value at each virtual A-scan position was the quotient of the RET measured at the inner segment/outer segment junction divided by the RNFL-T.
Results:
The dataset comprised 49 early glaucoma patients (mean ± standard deviation [SD]: 64 ± 10 years) and 49 healthy control subjects (61 ± 9 years). Glaucomatous eyes showed a statistically significant lower BIR globally (mean ± SD: 0.108 ± 0.008°/µm vs. 0.112 ± 0.009°/µm, P = 0.033), superiorly (0.116 ± 0.017°/µm vs. 0.126 ± 0.013°/µm, P = 0.0001), and inferiorly (0.112 ± 0.011°/µm vs. 0.121 ± 0.011°/µm, P < 0.0001), and increased BIR in the temporal quadrant (0.088 ± 0.015°/µm vs. 0.078 ± 0.014°/µm, P = 0.0001) compared to healthy eyes.
Conclusions:
We report a reduced BIR of the RNFL in early perimetric glaucoma, which can be interpreted as a sign of loss or change of intracellular microtubules and may contribute to a better understanding of early disease development. Prospective longitudinal studies are needed to determine whether BIR is altered in pre-perimetric human glaucoma before RNFL-T decline.
