Measuring Retinal Nerve Fiber Layer Birefringence, Retardation, and Thickness Using Wide-Field, High-Speed Polarization Sensitive Spectral Domain OCT

Abstract

PURPOSE. We presented a novel polarization sensitive optical coherence tomography (PS-OCT) system for measuring retinal nerve fiber layer (RNFL) birefringence, retardation, and thickness, and report on the repeatability of acquiring these quantities. METHODS.A new PS-OCT system, measuring at 840 nm, was developed that supports scan angles of up to 408 3 408 with an A-scan rate of 70 kHz. To test the performance and reproducibility, we measured 10 eyes of 5 healthy human volunteers five times each. All volunteers were imaged further with scanning laser polarimetry (SLP). The obtained RNFL birefringence, retardation, and thickness maps were averaged, and standard deviation maps were calculated. For quantitative comparison between the new PS-OCT and SLP, a circumpapillary evaluation within 2 annular segments (superior and inferior to the optic disc) was performed.RESULTS. High quality RNFL birefringence, retardation, and thickness maps were obtained. Within the superior and inferior segments, the mean retardation for individual eyes ranged from 208 to 28.98 and 17.28 to 28.28, respectively. The quadrant precision over the 5 consecutive measurements for each subject, calculated for the average retardation obtained within the superior and inferior quadrants ranged from 0.168 to 0.698. The mean birefringence ranged from 0.1068/lm to 0.1418/lm superior and 0.1018/lm to 0.1358/lm inferior, with a quadrant precision of 0.0018/lm to 0.0078/lm. The mean RNFL thickness varied from 114 to 150 lm superior, and 111 to 140.9 lm inferior (quadrant precision ranged from 3.6 to 11.9 lm). CONCLUSIONS.The new PS-OCT system showed high image quality and reproducibility, and, therefore, might be a valuable tool for glaucoma diagnosis. (Invest Ophthalmol Vis Sci. 2013; 54:72-84)

Polarization sensitive optical coherence tomography – a review [Invited]

“…In a healthy eye, this map shows a characteristic butterfly-shaped pattern that clearly shows the increased retardation caused by the thick RNFL in the vicinity of the ONH and along the arcuate nerve fiber bundles. Figure 14 shows a quantitative evaluation of the RNFL retardation, thickness, and birefringence obtained around the ONH of 10 healthy eyes [110]. The respective quantities were measured along a circle around the ONH, ranging from the temporal position (T) over the superior (S), the nasal (N), the inferior (I), and back to the T position.…”

Henle fiber layer phase retardation measured with polarization-sensitive optical coherence tomography

“…They used a histogram of DPPR data obtained near the photoreceptors to determine the maximum DPPR induced by the RNFL. Zotter et al used a similar approach, but did not perform any spatial averaging [14]. A novelty in our paper is that measurements at only two depths are used to determine the phase retardation that is induced by the HFL.…”

Polarization Sensitive Optical Coherence Tomography: A Review of Technology and Applications

“…In the vein of earlier scanning laser polarimetry approaches [137][138][139], PS-OCT was applied to investigate the RNFL using PS-OCT. After initial experiments in the primate retina [140], RNFL birefringence was measured in vivo in the human eye by performing circular scans around the optic nerve head [79,141]. Faster Fourier domain PS-OCT later enabled 2D mapping of RNFL birefringence and retardation as well as comparisons to scanning laser polarimetry [18,73,[142][143][144][145]. Exemplary PS-OCT fundus images mapping reflectivity and RNFL retardation in a human eye are shown in Figure 5.…”