Department of Health Sciences Faculty Articles
Randomized Controlled Trial of Electro-stimulation Therapies to Modulate Retinal Blood Flow and Visual Function in Retinitis Pigmentosa
Abstract
Purpose: We explored whether reduced systolic and diastolic blood flow velocities in the central retinal artery (CRA) of retinitis pigmentosa (RP) patients with a wide range of disease severity were related to level of visual function loss, and determined the test-retest variability of these central retinal blood velocity measures in RP. Methods: We measured the CRA peak systolic velocity (PSV) and end diastolic velocity (EDV) in 22 RP patients using color Doppler imaging (CDI) (GE Logiq 7 ultrasound) twice in each eye at each of two visits within a month. At each of these two visits, ETDRS visual acuity (VA), Goldmann visual fields (GVF), and 10-2 Humphrey visual fields (HVF) were completed. PSV and EDV were used to calculate mean flow velocity (MFV); correlations with visual function were adjusted for age and gender. Results: Mean within- and between-visit coefficients of variation were 16-22% for PSV and EDV. In eyes with reduced mean VA >0.3 logMAR, MFV was significantly lower on average than in eyes with better VA (p=0.037). Reduced MFV was also significantly associated with lower HVF mean deviation scores using size III target (p=0.007). Subjects with worse vision who completed the HVF with the size V target had significantly reduced MFV that was significantly correlated with decreased mean sensitivity at the 4 most central test locations around fixation (p=0.004). GVF log retinal areas (V4e and III4e) were not significantly related to MFV (p=0.79; p=0.78). Conclusions: The PSV and EDV measures in the CRA of RP patients were reliable and appeared reduced in cases of impaired central but not peripheral visual function loss. These measures of retrobulbar ocular blood flow are a promising outcome measure to determine the potential physiological basis for visual function changes in clinical trials for RP. Clinicaltrials.gov registration number: NCT02086890 Keywords: blood flow, retinitis pigmentosa, central retinal artery, visual function, mean flow velocity