Skip to main content

  • Can OCT Angiography Detect Preclinical Alzheimer Disease?

    By Lynda Seminara
    Selected and Reviewed By: Neil M. Bressler, MD, and Deputy Editors
    Add to My Bookmarks

    Journal Highlights

    JAMA Ophthalmology, November 2018

    Download PDF

    Current methods to diagnose asymp­tomatic preclinical Alzheimer disease (AD) are costly and invasive. Optical coherence tomographic angiography (OCT-A) is a noninvasive technique for analyzing retinal and microvascular anatomy, which is altered in early-stage AD. O’Bryhim et al. used OCT-A in a case-control study and found that the foveal avascular zone (FAZ) was larger in participants with preclinical AD than in those without AD. Hence, OCT-A may have utility as a rapid, noninvasive method to identify preclinical AD.

    For their study, the authors recruited 32 participants from an AD research center in St. Louis, Missouri. Results of extensive neuropsychometric testing determined that the enrollees were cognitively healthy. The participants received positron emission tomography and/or cerebral spinal fluid testing to determine biomarker status. Individu­als with previous ophthalmic disease, media opacity, diabetes, or uncontrolled hypertension were excluded. Primary outcome measures were retinal nerve fiber layer thickness, ganglion cell layer thickness, inner and outer foveal thickness, vascular density, macular volume, and FAZ size. Measurements were obtained by OCT-A. Mixed-effects analysis of covariance was applied to evaluate individual outcomes.

    Thirty participants (58 eyes) were included in the analysis (mean age, 74.5 years). Twenty-nine participants were white; 1 was African American. Four­teen had biomarkers positive for AD, denoting preclinical AD (mean age, 73.5 years). The 16 participants without biomarkers served as the control group (mean age, 75.4 years). The group with positive biomarkers had larger FAZs (mean, 0.364 vs. 0.275 mm2; p = .002) and narrower inner foveae (mean, 66.0 vs. 75.4 μm; p = .03).

    These findings suggest that people with biomarker-positive preclinical AD may experience retinal vascular and architectural changes before their cog­nitive symptoms manifest clinically. Ac­cording to the authors, this may imply that the retina undergoes neuronal loss and vascular modifications much earli­er in the disease process than previous­ly thought. However, they cautioned, confounding factors (unrelated to FAZ enlargement) may have contributed to the results. (Also see related commentary by Christine A. Curcio, PhD, in the same issue.)

    The original article can be found here.