Intravascular oxygen saturation in retinal vessels in normal subjects and open‐angle glaucoma subjects

Abstract

ABSTRACT.Purpose: To measure the oxygen saturation (SO 2 ) in retinal arterioles and venules in patients with glaucomatous optic neuropathy. Methods: We examined SO 2 in retinal arterioles and venules simultaneously by imaging spectrometry. Oxygen saturation was evaluated according to the difference of the extinction spectra of haemoglobin and oxyhaemoglobin. The arteriovenous difference (avD) was calculated by (SO 2art -SO 2ven ). The optic nerve head topography was estimated by Heidelberg retinal tomography and the visual field using the Octopus G1. We examined one eye in each of 58 healthy persons (mean age 58.6 ± 10.7 years; mean rim area 1.52 ± 0.33 mm 2 ; mean defect 0.65 ± 1.31 dB; mean intraocular pressure [IOP] 18.5 ± 2.7 mmHg), 49 patients with normal-tension primary open-angle glaucoma (NTG) (mean age 63.0 ± 8.5 years; mean rim area 0.89 ± 0.34 mm 2 ; mean defect 5.4 ± 4.1 dB; mean IOP 19.2 ± 2.9 mmHg), and 45 patients with high-tension primary openangle glaucoma (POAG) (mean age 62.6 ± 10.3 years; mean rim area 0.97 ± 0.47 mm 2 ; mean defect 7.1 ± 6.4 dB; mean IOP 31.6 ± 10.8 mmHg). Results: The intraclass correlation coefficients of the SO 2 measurement were 0.82 (arteriole) and 0.59 (venule). In normal eyes, the SO 2art , SO 2ven and avD were 92.3 ± 3.4%, 55.7 ± 6.8% and 36.6 ± 7.0%, respectively. Equivalent data were 89.7 ± 5.4%, 56.0 ± 8.3% and 33.7 ± 10.6%, respectively, in NTG eyes and 91.4 ± 4.0%, 58.3 ± 10.5% and 33.1 ± 11.5%, respectively, in POAG eyes. Over all examined eyes, the arteriolar SO 2 and the retinal arterio-venous difference correlated significantly with the rim area. Conclusion: Eyes with NTG showed significantly decreased arteriolar SO 2 . These changes were not seen in POAG patients.

Oxygen saturation measurements of the retinal vasculature in treated asymmetrical primary open-angle glaucoma using hyperspectral imaging

“…17 In this study, no significant differences were observed in the oxygen saturation of the retinal venules between normal and glaucomatous eyes (normal-tension glaucoma and POAG). Arteriolar oxygen saturation was significantly lower in the normal-tension glaucoma cohort compared with normal subjects but not in the POAG cohort.…”

“…Studies using various retinal oximetry devices to measure the oxygen saturation of the retinal vasculature in glaucoma have been reported. [12][13][14][15][16][17][18][19][20] Hyperspectral imaging combines spectroscopy with digital imaging whereby spectral data (using numerous contiguous wavelengths of light) are obtained in every pixel of an image plane. An oximetry study of the retinal vascular network using a hyperspectral imaging system (images acquired using more than three contiguous wavelengths) in glaucoma has not yet been reported.…”

Retinal oximeter for the blue-green oximetry technique

“…[1][2][3][4][5] Disparities in oxygen utilization between the left and right eyes, such as those that occur in diabetic retinopathy, could be measured to screen for retinal disease as well as for monitoring responses to interventions and experimental treatments. 6,7 Retinal venous oxygen saturation has been demonstrated to predictably decrease during hemorrhagic shock, to rise with resuscitation, and to correlate with central venous oxygen saturation. 2,3,8,9 Early goal-directed therapy (EGDT) for patients with severe sepsis-a resuscitation algorithm using physiologic end points, including central venous oxygen saturationhas been shown to increase the survival of these patients.…”

Normal-Tension (Low-Tension) Glaucoma

“…The future of understanding the ischemic aspect in the development of glaucoma may be by optical measurement of retinal vessel oxygenation. Oxygenation of retinal arteries was found to be lower in normal-tension glaucoma patients than in healthy subjects (Michelson et al, 2006). Other factors influence the perfusion of the optic nerve and participate in the development and progression of the disease.…”