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Mitra Sehi, David S Greenfield, Krishna S Kishor, Rosa Catalina Ruiz, Sowmya Srinivas, Shawn M Iverson, Iman Goharian; Relationship between Retinal Blood Flow, Ganglion Cell Function and Retinal Oxygenation in Glaucomatous and Normal Eyes. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4731. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To examine the relationship between retinal blood flow (RBF), retinal ganglion cell (RGC) function, and retinal oxygen saturation (SO2) in glaucoma patients compared with normal controls.
One randomly selected eye of glaucoma patients and normal controls underwent standard automated perimetry (SAP), retinal oximetry using spectrophotometric retinal oximeter (Oxymap ehf., Iceland), RBF using Doppler spectral-domain optical coherence tomography (SDOCT, Optovue Inc, CA) and RGC function using pattern electroretinogram for glaucoma (PERG, Paradigm, UT). Exclusion criteria for both groups were visual acuity <20/30, unreliable SAP (>20% FL; >15% FP), thyroidopathies, hemoglobinopathies, cardiovascular and pulmonary diseases. Intraocular pressure (IOP) and blood pressure (BP) were measured and mean ocular perfusion pressure (MOPP) was calculated. The SO2 in arteries and veins was extracted. The average arterial and venous SO2 (a.SO2, v.SO2) and the arteriovenous difference (ΔSO2) were calculated. The RBF was derived from the Doppler frequency shift.
23 glaucoma patients (age 68.3±10.8 yrs) and 22 controls (age 61.5±18.2 yrs; p=0.14) were included. SAP pattern standard deviation (PSD) was greater in glaucoma vs. controls (7.2±4.7dB; 1.7±0.5dB; p<0.001). The IOP and MOPP in glaucoma (14.4±4.2mmHg; 45.8±5.8mmHg) and controls were similar (14.3±3.3mmHg; 45.8±6.1mmHg; p>0.05). Glaucomatous and normal eyes had similar a.SO2 (92.9±6.7%; 90.1±4.9% respectively; p=0.11), and v.SO2 (45.4±11.0%; 48.0±7.7% respectively; p=0.36). ΔSO2 was higher in glaucoma vs. controls (47.6±8.2%; 42.1±6.2%; p=0.015). The PERG amplitude was lower in glaucoma vs. controls (0.29±0.18µV; 0.63±0.33µV; p<0.001). The RBF was lower in glaucoma vs. controls (28.0±11.2µL/min; 40.2±11.5 µL/min; p=0.01). In glaucoma, The v.SO2 and IOP (r= 0.48; p=0.02) and ΔSO2 and MOPP (r= -0.60; p=0.003) were inversely correlated. The ΔSO2 was directly correlated with IOP (r=0.63; p=0.001), inversely correlated with MOPP (r= 0.60; p=0.003), and inversely correlated with PERG amplitude (r= 0.46; p=0.03) In glaucoma. The correlations between RBF and SO2 parameters were not significant in either group (P>0.05).
These data suggest that glaucomatous eyes with RGC dysfunction demonstrate greater oxygen consumption compared with normal controls.
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