In the JournalsPerspective

Spectral domain OCT may determine Alzheimer's biomarkers

The use of spectral domain OCT measurements may prove beneficial in determining biomarkers of Alzheimer’s disease, according to findings published in the journal, Ophthalmology.

Victor T.T. Chan , MB, and colleagues conducted a systematic review and meta-analysis to examine SD-OCT measurements in Alzheimer’s disease (AD) and mild cognitive impairment.

“The retina long has been considered a window to study disorders in the central nervous system because it is an extension of the brain embryologically, anatomically and physiologically,” Chan, of the department of ophthalmology and visual sciences and the department of medicine and therapeutics at the Chinese University of Hong Kong, and colleagues wrote. “Extensive loss of retinal ganglion cells and their axons has been reported by histopathologic studies in eyes from AD patients and AD animal models.”

The researchers conducted a search of literature to find studies published prior to December 2017 assessing the association between Alzheimer’s disease, mild cognitive impairment and measurements of SD-OCT measurement.

The measurements included ganglion cell-inner plexiform layer (GC-IPL), ganglion cell complex (GCC), macular volume and choroidal thickness. Retinal nerve fiber layer and macular thickness were also measured.

Chan and colleagues found 30 eligible studies involving 1,257 patients with Alzheimer’s disease, 301 patients with mild cognitive impairment and 1,460 controls.

Patients with Alzheimer’s disease showed a significant difference in GC-IPL thickness and GCC thickness when compared with controls, the researchers wrote. Patients with Alzheimer’s had significant differences in macular volume and macular thickness of all inner and outer sectors when compared with controls.

In patients with Alzheimer’s disease, peripapillary retinal nerve fiber layer and choroidal thickness were found to be thinner. – by Earl Holland Jr.


Disclosure: Chan reported no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.

The use of spectral domain OCT measurements may prove beneficial in determining biomarkers of Alzheimer’s disease, according to findings published in the journal, Ophthalmology.

Victor T.T. Chan , MB, and colleagues conducted a systematic review and meta-analysis to examine SD-OCT measurements in Alzheimer’s disease (AD) and mild cognitive impairment.

“The retina long has been considered a window to study disorders in the central nervous system because it is an extension of the brain embryologically, anatomically and physiologically,” Chan, of the department of ophthalmology and visual sciences and the department of medicine and therapeutics at the Chinese University of Hong Kong, and colleagues wrote. “Extensive loss of retinal ganglion cells and their axons has been reported by histopathologic studies in eyes from AD patients and AD animal models.”

The researchers conducted a search of literature to find studies published prior to December 2017 assessing the association between Alzheimer’s disease, mild cognitive impairment and measurements of SD-OCT measurement.

The measurements included ganglion cell-inner plexiform layer (GC-IPL), ganglion cell complex (GCC), macular volume and choroidal thickness. Retinal nerve fiber layer and macular thickness were also measured.

Chan and colleagues found 30 eligible studies involving 1,257 patients with Alzheimer’s disease, 301 patients with mild cognitive impairment and 1,460 controls.

Patients with Alzheimer’s disease showed a significant difference in GC-IPL thickness and GCC thickness when compared with controls, the researchers wrote. Patients with Alzheimer’s had significant differences in macular volume and macular thickness of all inner and outer sectors when compared with controls.

In patients with Alzheimer’s disease, peripapillary retinal nerve fiber layer and choroidal thickness were found to be thinner. – by Earl Holland Jr.


Disclosure: Chan reported no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.

    Perspective
    Mark Wu

    Mark Wu

    Chan and colleagues performed a meta-analysis of 30 different studies that explored the relationship between macular measurements obtained by SD-OCT and Alzheimer’s disease. The results suggest an association between Alzheimer’s disease and loss of macular tissue.

    While Chan et al. offered some convincing data with good validity, current understanding of Alzheimer’s disease pathogenesis does not provide a clear explanation of the cause of reduced macular thickness and volume in these patients when the disease is considered to be cortical in origin. Additionally, reduced macular thickness and volume findings would still prompt the primary care optometrist to consider other more common ocular diseases such as age-related macular degeneration and glaucoma before Alzheimer’s disease.

    Optometrists would require a more specific biomarker in the retina than generalized macular or ganglion cell tissue loss in order to effectively and efficiently screen for potential Alzheimer’s patients using noninvasive technology. As the authors admitted, further research in the area is required before instituting a formal screening protocol for retinal markers linked to Alzheimer’s disease.

    • Mark Wu, OD, FAAO
    • Assistant clinical professor, co-chief
      Binocular Vision Clinic, UC Berkeley

    Disclosures: Wu reports no relevant financial disclosures.