Visible Light Optical Coherence Tomography of Peripapillary Retinal Nerve Fiber Layer Reflectivity in Glaucoma

Abstract

Purpose To evaluate the clinical utility of visible light optical coherence tomography (VIS-OCT) and to test whether VIS-OCT reflectivity and spectroscopy of peripapillary retinal nerve fiber layer (pRNFL) are correlated with severity of glaucoma, compared with standard-of-care OCT thickness measurements. Methods In total 54 eyes (20 normal, 17 suspect/preperimetric glaucoma [GS/PPG], 17 perimetric glaucoma [PG]) were successfully imaged with complete datasets. All the eyes were scanned by a custom-designed dual-channel device that simultaneously acquired VIS-OCT and near-infrared OCT (NIR-OCT) images. A 5 × 5 mm 2 scan was taken of the pRNFL. The pRNFL reflectivity was calculated for both channels and the spectroscopic marker was quantified by pVN, defined as the ratio of VIS-OCT to NIR-OCT pRNFL reflectivity. The results were compared with ophthalmic examinations and Zeiss Cirrus OCT. Results VIS-OCT pRNFL reflectivity significantly, sequentially decreased from normal to GS/PPG to PG, as did NIR-OCT pRNFL reflectivity. The pVN had the same decreasing trend among three groups. Normal and GS/PPG eyes were significantly different in VIS-OCT pRNFL reflectivity ( P = 0.002) and pVN ( P < 0.001), but were not in NIR-OCT pRNFL reflectivity ( P = 0.14), circumpapillary RNFL thickness ( P = 0.17), or macular ganglion cell layer and inner plexiform layer thickness ( P = 0.07) in a mixed linear regression model. Conclusions VIS-OCT pRNFL reflectivity and pVN better distinguished GS/PPG from normal eyes than Cirrus OCT thickness measurements. Translational Relevance VIS-OCT pRNFL reflectivity and pVN could be useful metrics in the early detection of glaucoma upon further longitudinal validation.

Macular Oxygen Saturation in Glaucoma Using Retinal Oximetry of Visible Light Optical Coherence Tomography

“…The illumination power on pupil was less than <0.25 mW (VIS) and 0.9 mW (NIR), respectively, meeting the safety standards of the ANSI for ophthalmic instrument. Details of the calculation can be seen in the supplementals of our previous publication 30 . We used a tunable lens to correct the spherical refractive error.…”

A dual-channel visible light optical coherence tomography system enables wide-field, full-range, and shot-noise limited human retinal imaging

“…Since its conception in the 1990s, optical coherence tomography (OCT) has been one of the most influential imaging methods in biophotonics and has revolutionized clinical practice in ophthalmology 1 . Visible light optical coherence tomography (VIS-OCT) is a burgeoning modification of OCT that uses visible instead of near-infrared (NIR) illumination and has been demonstrated for preclinical and clinical ophthalmic imaging 2 – 4 . One advantage of VIS-OCT is that visible wavelengths demonstrate higher levels of backscattering from biological tissues than longer near-infrared wavelengths 5 and reveal distinct spectral contrast in imaging pigmentation (e.g.…”

Targeted spectroscopy in the eye fundus

“…Pi et al measured, quantitatively, retinal blood oxygen saturation in vitro and in rats [26]. Recently, Song et al have shown that the reflectance signal from VIS-OCT could better distinguish glaucoma subjects from normal eyes than thickness measurements from OCT [27]. However, the acquisition time was 2.6 sec at 50 kHz A-line speed and the laser power at the pupil was 0.25 mW for a wavelength range of 545 to 580 nm.…”