Retinal blood flow in glaucomatous eyes with single-hemifield damage

Purpose: To examine the hypotheses that in glaucomatous eyes with single-hemifield damage, retinal blood flow (RBF) is significantly reduced in the retinal hemisphere corresponding with the abnormal visual hemifield and that there are significant associations among reduced retinal sensitivity (RS) in the abnormal hemifield, RBF, and structural measurements in the corresponding hemisphere.

Design: Prospective, nonrandomized, case-control study.

Participants: Thirty eyes of 30 patients with glaucoma with visual field loss confined to a single hemifield and 27 eyes of 27 controls.

Methods: Normal and glaucomatous eyes underwent spectral-domain optical coherence tomography (SD-OCT) and standard automated perimetry. Doppler SD-OCT with a double-circle scanning pattern was used to measure RBF. The RBF was derived from the recorded Doppler frequency shift and the measured angle between the beam and the vessel. Total and hemispheric RBF, retinal nerve fiber layer (RNFL), and ganglion cell complex (GCC) values were calculated. The RS values were converted to 1/Lambert. Analysis of variance and regression analyses were performed.

Main outcome measures: Total and hemispheric RS, RBF, RNFL, and GCC values.

Results: The total RBF (34.6±12.2 μl/minute) and venous cross-sectional area (0.039 ± 0.009 mm(2)) were reduced (P<0.001) in those with glaucoma compared with controls (46.5 ± 10.6 μl/minute; 0.052 ± 0.012 mm(2)). Mean RBF was reduced in the abnormal hemisphere compared with the opposite hemisphere (15.3 ± 5.4 vs. 19.3 ± 8.4 μl/minute; P = 0.004). The RNFL and GCC were thinner in the corresponding abnormal hemisphere compared with the opposite hemisphere (87.0 ± 20.2 vs. 103.7 ± 20.6 μm, P = 0.002; 77.6 ± 12.1 vs. 83.6 ± 10.1 μm, P = 0.04). The RBF was correlated with RNFL (r = 0.41; P = 0.02) and GCC (r = 0.43; P = 0.02) but not the RS (r = 0.31; P = 0.09) in the abnormal hemisphere. The RBF (19.3 ± 8.4 μl/minute), RNFL (103.7 ± 20.6 μm), and GCC (83.6 ± 10.1 μm) were reduced (P<0.05) in the hemisphere with apparently normal visual field in glaucomatous eyes compared with the mean hemispheric values of the normal eyes (23.2 ± 5.3 μl/minute, 124.8 ± 9.6 μm, and 96.1 ± 5.7 μm, respectively).

Conclusions: In glaucomatous eyes with single-hemifield damage, the RBF is significantly reduced in the hemisphere associated with the abnormal hemifield. Reduced RBF is associated with thinner RNFL and GCC in the corresponding abnormal hemisphere. Reduced RBF and RNFL and GCC loss also are observed in the perimetrically normal hemisphere of glaucomatous eyes.