Alzheimer’s
Imaging through the visual system in Alzheimer's disease, with the technology currently in widespread use for the diagnosis and management of eye disease such as glaucoma and macular degeneration, is proving to be promising. In vivo cross-section imaging during an annual comprehensive eye exam has been available for a decade for glaucoma and macular degeneration, and this same imaging, using Optical Coherence Tomography, has been demonstrated to show deficits specific to AD and mild cognitive impairment. These deficits are in the form of nerve fiber layer tissue drop out in the retina and optic nerve. The retrograde loss of nerve fiber layer tissue in the retina and optic nerve may be an early biomarker of AD, and these deficits in the nerve fiber layer of the retina and optic nerve may be the earliest sign of AD, even prior to damage to the hippocampal region that impacts memory.
1. Introduction
Biomarkers for the early diagnosis, management, and treatment of Alzheimer’s disease (AD) are important. In vivo cross-section imaging during an annual comprehensive eye exam with a dilated pupil has been available for a decade for glaucoma and macular degeneration, and this same imaging, using Optical Coherence Tomography (OCT), has been demonstrated to show deficits specific to AD [1–7] and mild cognitive impairment (MCI) [2]. These deficits are in the form of nerve fiber layer tissue drop out in the retina and optic nerve. The retrograde loss of nerve fiber layer tissue in the retina and optic nerve may be an early biomarker of AD, and these deficits in the nerve fiber layer of the retina and optic nerve may be the earliest sign of AD, even prior to damage to the hippocampal region that impacts memory. The OCT technology used to identify nerve fiber layer defects in AD reported in the literature is an older version often referred to as Time Domain-OCT. Time Domain-OCT (Time-OCT) only resolved the retina to approximately ten microns, whereas newer clinical OCT imaging systems High Definition/Resolution/Fourier/Spectral Domain-OCT (HDR-OCT) can resolve the retina to five microns or less, acquire images faster, reregister retinal location, and does not require the dilation of the pupils of the eye. Faster acquisition is important for patients with cognitive impairment such as AD. The ability to reregister exact location enables more accurate followup and longitudinal study.
Additional technical information:
- Retinal nerve fiber layer structure abnormalities in early Alzheimer's disease: evidence in optical coherence tomography.
- Retinal Abnormalities in Early Alzheimer’s Disease
- Optical coherence tomography as a progression marker in mild cognitive impairment and Alzheimer´s disease
- Detection of retinal nerve fiber layer defects in Alzheimer’s disease using SD-OCT