Decreased retinal-choroidal blood flow in retinitis pigmentosa as measured by MRI

To evaluate retinal and choroidal blood flow (BF) using high-resolution magnetic resonance imaging (MRI) as well as visual function measured by the electroretinogram (ERG) in patients with retinitis pigmentosa (RP). MRI studies were performed in 6 RP patients (29-67 years) and 5 healthy volunteers (29-64 years) on a 3-Tesla scanner with a custom-made surface coil. Quantitative BF was measured using the pseudo-continuous arterial spin-labeling technique at 0.5 x 0.8 x 6.0 mm. Full-field ERGs of all patients were recorded. Amplitudes and implicit times of standard ERGs were analyzed. Basal BF in the posterior retinal-choroid was 142 +/- A 16 ml/100ml/min (or 1.14 +/- A 0.13 mu l/mm(2)/min) in the control group and was 70 +/- 19 ml/100ml/min (or 0.56 +/- A 0.15 mu l/mm(2)/min) in the RP group. Retinal-choroidal BF was significantly reduced by 52 +/- A 8 % in RP patients compared to controls (P < 0.05). ERG a- and b-wave amplitudes of RP patients were reduced, and b-wave implicit times were delayed. There were statistically significant correlations between a-wave amplitude and BF value (r=0.9, P < 0.05) but not between b-wave amplitude and BF value (r =0.7, P=0.2). This study demonstrates a novel non-invasive MRI approach to measure quantitative retinal and choroidal BF in RP patients. We found that retinal-choroidal BF was markedly reduced and significantly correlated with reduced amplitudes of the a-wave of the standard combined ERG.