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Stefan Steiner, Sylvia Desissaire, Florian Schwarzhans, Georg Fischer, Hemma Resch, Michael Pircher, Christoph K Hitzenberger, Clemens Vass; Structure-function relationship of circumpapillary polarisation sensitive optical coherence tomography scans and visual field maps in glaucoma. Invest. Ophthalmol. Vis. Sci. 2020;61(7):3940.
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© ARVO (1962-2015); The Authors (2016-present)
To measure the circumpapillary retinal nerve fiber layer (RNFL) in early glaucoma using polarisation sensitive optical coherence tomography (PS-OCT) and to correlate PS-OCT data with visual field (VF) maps.
We included 21 eyes of early glaucoma patients (66.2±8 years) and 22 eyes of healthy controls (57.6±8 years) in our investigation. Early glaucoma was defined as glaucomatous appearance of the optic nerve head, glaucomatous VF loss pattern and a mean deviation (MD) of -6 dB or better. All subjects underwent a circumpapillary PS-OCT scan with a diameter of 3.0 mm (circular B-scans with 2048 A-scans, 100 records) with a custom-built PS-OCT operating at 860nm with an A-scan rate of 70 kHz and an integrated retinal tracker. The best 50 records were averaged and used for analysis. Circumpapillary RNFL thickness (RNFL-T) was extracted from the intensity data, the retardation (RET) profile was based on RET data extracted at the photoreceptor layer and birefringence (BIR) was calculated by dividing RET by RNFL-T. The circumpapillary scan and VF tests were divided into 8 sectors using the adapted Garway-Heath scheme of David Huang et al. see figure 1. These sectors were classified into affected and unaffected sectors. Affected sectors were defined as (1) a mean pattern deviation (PD) of -3 dB or less or (2) a mean probability PD of 0.5 or more, whereas a probability of <5%, <2%, <1%, <0.5% was defined as 1, 2, 3, 4, respectively. T-test was used to compare means.
In healthy versus early glaucoma subjects the MD of the 24-2 VF tests was -0.6 dB (±1.4) vs. -2.8 dB (±1.7), (p<0.001), global RNFL-T was 103 µm(±16) vs. 85 µm(±16) (p<0.001), global RET was 14.7°(±3.0) vs. 10.4°(±2.7) (p<0.001) and global BIR was 0.14°/µm (±0.02) vs. 0.12°/µm (±0.02) (p≤ 0.001).Affected compared to unaffected sectors in glaucoma showed significantly smaller (1) RNFL-T in sector 3 (p=0.032), 4 (p=0.006), 5 (p=0.026), (2) RET in sector 1 (p=0.041), 3 (p=0.011), 4 (p=0.01), 5 (p=0.019), (3) BIR in sector 3 (p=0.001) see table 1. Comparisons of unaffected sectors between glaucoma and healthy eyes are shown in table 1.
PS-OCT is delivering additional information about the structure of the RNFL. RET and BIR may contribute to an improved early glaucoma detection. For a more precise analysis a larger dataset and refined methods are needed.
This is a 2020 ARVO Annual Meeting abstract.
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