Scientists Find Biomarker of Degenerative Diseases in the Eye

A new study reports finding a well-known biomarker - associated with early diagnosis of a range of degenerative diseases - in the human eye.

Researchers from the Boston Medical Center (BMC) have reported finding the neurofilament light chain in the vitreous humor. This transparent, colorless fluid fills the gap in the eye, especially between the lens and the retina. The biomarker, explored as an early warning sign for neurodegeneration, was previously found within the blood and cerebrospinal fluid.

Their findings were published in the journal Alzheimer's Research & Therapy.

Clues in Early Detection of Alzheimer's, Parkinson's

The study, aside from detecting neurofilament light chain (NfL) in the vitreous humor, also aims to inquire about its associations with various diseases. Biomarkers such as the NfL have invited significant interest in studying neurodegenerative diseases because of their potential in early detection of conditions from easily accessible clues.

Diseases such as Alzheimer's and Parkinson's are generally attributed to the deteriorating function of nerve cells, either in the central or the peripheral nervous systems. This growing loss of function eventually leads to irreparable cell death. These conditions remain without cure so far, although there have been treatments available.

Treatments and procedures targeted to these diseases can only alleviate physical and mental symptoms. On the other hand, early treatment before the latter stages of these diseases can help delay, if not prevent, the progression after the onset.

"One of the biggest priorities in Alzheimer's disease research is to develop ways to diagnose the disease before the onset of symptoms, which would allow for early treatment that could help halt the progression of this fatal disease," said first and corresponding author of the study Manju Subramanian, MD, also an ophthalmologic surgeon at BMC, in a press release from the Boston Medical Center.

Collection and Testing of Vitreous Humor Samples

For the study, researchers collected vitreous humor samples from 77 patients at the BMC set to undergo a previously scheduled eye surgery. In this population, 63 percent were male, and the mean age for the dataset was 56.2 years.

After analyzing the composition of the collected samples, all 77 patients had the Neurofilament light chain in their eye fluids. Furthermore, researchers observed that higher concentrations of the biomarker were associated with increased levels of other biomarkers, such as amyloid-beta and tau proteins - markers explicitly related to Alzheimer's disease.

Meanwhile, proponents of the study were not able to establish a link between Neurofilament light chain levels in the vitreous humor and eye disease, suggesting that the detected levels are not directly affected by the clinical eye conditions present in the patients.

"As an extension of the brain, the eye can provide important insight about what's happening pathologically in the brain," Subramanian further explained. He expressed hope that their work will provide a novel method in taking clues from other parts of the body to detect neurodegenerative diseases before causing "irreversible damage."