Choroidal Blood Flow Decreases with Age: An MRI Study

Abstract

Purpose To verify that a visual fixation protocol with cued eye blinks achieves sufficient stability for magnetic resonance imaging (MRI) blood-flow measurements and to determine if choroidal blood flow (ChBF) changes with age in humans. Methods The visual fixation stability achievable during an MRI scan was measured in five normal subjects using an eye-tracking camera outside the MRI scanner. Subjects were instructed to blink immediately after recorded MRI sound cues but to otherwise maintain stable visual fixation on a small target. Using this fixation protocol, ChBF was measured with MRI using a 3 Tesla clinical scanner in 17 normal subjects (24–68 years old). Arterial and intraocular pressures (IOP) were measured to calculate perfusion pressure in the same subjects. Results The mean temporal fluctuations (standard deviation) of the horizontal and vertical displacements were 29 ± 9 μm and 38 ± 11 μm within individual fixation periods, and 50 ± 34 μm and 48 ± 19 μm across different fixation periods. The absolute displacements were 67 ± 31 μm and 81 ± 26 μm. ChBF was negatively correlated with age (R =−0.7, p = 0.003), declining 2.7 ml/100 ml/min per year. There were no significant correlations between ChBF versus perfusion pressure, arterial pressure, or IOP. There were also no significant correlations between age versus perfusion pressure, arterial pressure, or IOP. Multiple regression analysis indicated that age was the only measured independent variable that was significantly correlated with ChBF (p = 0.03). Conclusions The visual fixation protocol with cued eye blinks was effective in achieving sufficient stability for MRI measurements. ChBF had a significant negative correlation with age.

What ocular and systemic variables affect choroidal circulation in healthy eyes

“…There have been several reports describing that blood flow is negatively correlated with age. [ 49 50 ] The number of choroidal arterioles and the fluorescent intensity in the macular region were observed to decrease with aging using indocyanine green angiography [51] . Dye filling was delayed, and vessels were thickened, running a straight course (instead of tortuous) with reduced branching in older subjects [51] .…”

Glaucoma history and risk factors

“…As a consequence, glaucoma can be expected to be associated with other age-related diseases such as macular degeneration, 20 vascular diseases, 23 and obstructive sleep apnea 24 for example. However this is not a direct link for most age-related diseases.…”

Defective Choroidal Blood Flow Baroregulation and Retinal Dysfunction and Pathology Following Sympathetic Denervation of Choroid

“…Many diseases or conditions affecting retina have impaired ChBF as concomitants, including AMD, 64 – 75 chronic hypertension, 76 , 77 insulin-dependent diabetes, 78 glaucoma, 79 – 82 ischemic outer retinal disease, 83 myopic retinopathy, 84 central serous chorioretinopathy, 85 and aging. 13 , 21 , 66 , 86 – 88 Disturbances in neurogenic maintenance of basal tone or adaptive ChBF responses could be contributing factors to retinal declines seen in these diseases or conditions, although loss and narrowing of choroidal vessels may also contribute as well. 27 , 76 , 89 – 92 Much of the attention on disease-related ChBF impairments has focused on diminished ChBF.…”