With age, aspects of human biology and daily life compound, at times driving towards neurodegenerative disease that can cause memory loss, confusion, trouble walking, and personality changes. The current standard of care for neurodegenerative diseases such as Alzheimer’s or Parkinson’s involves symptom management, slowing disease progression, and implementing supportive therapies.
Patients with neurodegenerative diseases often complain of visual disturbances well in advance of the full disease onset. In fact, self-reported visual changes can occur as many as 10 years prior to onset of a disease’s symptoms and signs. This provides an opportunity for early intervention.
Neurodegenerative disease biomarkers can be found in cerebrospinal fluid (CSF), blood, and the retina. However, CSF is invasive, and bloodwork may present only low concentrations of biomarkers. Ophthalmic testing modalities such as visual contrast sensitivity, visual electrophysiology, optical imaging offer viable biomarkers for these diseases.
Research shows that visual electrophysiology tests such as electroretinography (ERG) and visually evoked potentials (VEP) present consistent patterns of expression in the retina. Patients with Parkinson’s disease have increased latencies in VEP and decreases in pattern ERG (PERG) responses, which correlate linearly with retinal nerve fiber layer thickness. Meanwhile, Alzheimer’s disease tends to present a decreased latency of the second peak of the flash VEP.
Although clear paths for treating early stages of neurodegenerative diseases remain undefined, researchers are actively conducting deeper preclinical studies to discover new ways to manage neuroinflammation, protect existing neurons (neuroprotection), and assess genetic contributors.