Purchase this article with an account.
Gilbert T. Feke, Bradley T. Hyman, Robert A. Stern, Louis R. Pasquale; Retinal Blood Flow and Nerve Fiber Layer Thickness in Patients with Mild Cognitive Impairment or Probable Alzheimer's Disease. Invest. Ophthalmol. Vis. Sci. 2011;52(14):2132.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
In a previous study (IOVS 2007; 48:2285-89) we reported that retinal abnormalities in patients with early Alzheimer’s Disease (AD) include thinning of the superior retinal nerve fiber layer (RNFL), narrow retinal veins, and decreased blood flow in these veins. The purpose of this study is to determine whether these abnormalities are already present in patients with mild cognitive impairment (MCI).
Subjects for the study underwent cognitive testing at either the Massachusetts General Hospital Alzheimer’s Disease Research Center or the Boston University Alzheimer’s Disease Center. Investigators performing the retinal assessments were masked to the cognitive status of the subjects. Of the 34 subjects enrolled in the study, 7 were diagnosed with probable AD (age 72.7±13.6 years), 10 with MCI (age 70.9±13.9 years), and 17 with normal cognition (NC) (age 70.1±7.1 years). Blood column diameter, centerline blood speed, and retinal blood flow rate were measured in a major temporal retinal vein in one eye of each subject using a Canon CLBF 100 retinal laser Doppler blood flow instrument. RNFL thickness was measured using Stratus OCT. Results were compared among the three groups using ANOVA with post hoc tests.
There were no significant differences in age, mean arterial pressure, heart rate, or intraocular pressure among the groups. AD patients had significantly narrower veins (135±10 µm) than MCI subjects (153±20 µm; p=0.033) or NC subjects (156±16 µm; p=0.007). Blood speed was 29.1±5.5 mm/s in AD, 28.0±4.1 mm/s in MCI, and 34.3±9.3 in NC. The difference in blood speed between MCI and NC was significant (p=0.041). Blood Flow was 12.4±2.5 µl/min in AD, 15.6±4.4 µl/min in MCI, and 19.4±5.0 in NC. The differences in blood flow between AD and NC (p=0.002) and between MCI and NC were significant (p=0.042). Superior RNFL thickness was 110±15 µm in AD, 120±17 µm in MCI, and 115±16 in NC. The differences were not significant (p=0.43).
The results show that retinal blood flow is decreased in MCI, as well as in AD, compared to that in subjects with normal cognition. This interim report suggests that hemodynamic abnormalities may precede neural loss in the retina in cognitively impaired subjects.
This PDF is available to Subscribers Only