Alzheimer’s disease may be detectable from changes in the foveal avascular zone
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Evaluating changes in the foveal avascular zone using OCT angiography to identify Alzheimer’s disease may be a quicker, easier and less invasive diagnostic strategy than traditional methods, according to a speaker.
“This suggests that once we use machine learning and artificial intelligence, AD may be detectable at early stages and noninvasively by techniques such as OCT angiography. It might help us identify resilient individuals, but also individuals at high risk for developing AD in the future,” Rajendra S. Apte, MD, PhD, said at Retinal Subspecialty Day at the virtual American Academy of Ophthalmology meeting.
Traditionally, Alzheimer’s disease is diagnosed by biomarkers imaged with positron emission tomography (PET), typically with Pittsburgh compound, or cerebrospinal fluid (CSF) testing for amyloid beta 42 and tau protein. Both modalities are time consuming, expensive and invasive, Apte said.
Apte presented data from a single-center, case-control study to evaluate the possibility of detecting Alzheimer’s disease before the onset of symptoms from alterations in retinal microvasculature as examined by OCT and OCTA. Subjects who underwent either PET imaging or CSF testing within a year and who had no evidence of dementia were included in the study.
Subjects in the biomarker positive cohort had a significantly thinner inner foveal thickness compared with biomarker negative subjects. In addition, the biomarker positive subjects had a significantly larger foveal avascular zone (FAZ) of 0.364 µm compared with 0.278 µm in biomarker negative subjects, Apte said.
After a 3-year period, with the data currently under review, the biomarker positive cohort continued to have a statistically significantly larger avascular zone compared with the biomarker negative cohort, he said.
“Biomarker positive subjects demonstrated an enlargement of the FAZ. The mechanism is unclear, but there are several vascular as well as structural abnormalities that may explain this,” he said.
These results may be applied to other diseases in the brain and other dementias that are characterized by neurodegeneration, Apte said.
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Apte RS. OCT and OCT angiographic imaging of the retina in Alzheimer disease. Presented at: American Academy of Ophthalmology annual meeting; Nov. 13-15, 2020 (virtual meeting).
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