Brain Diseases May Be Diagnosed Using Retinal Scans

A study conducted by the University of Eastern Finland suggests that diseases of the central nervous system (CNS) may show as pathological changes in the retina of the eye. Researchers stated that findings from mouse models showed that eye examination can be used as a non-invasive test to screen diseases of the human brain especially Huntington's disease (HD) and Alzheimer's disease (AD).

Science Daily reported that the retina, which is known as the light sensing tissue on the bottom of the eye, can be acknowledged as a significant part of the central nervous system (CNS). According to the report, the research, conducted by Dr. Henri Leinonen, who explored functional abnormalities in the retinas of mice for his Ph.D. project, also said that during fetal development, the retina matures from the area of the brain and its sensation closely resembles that of the brain.

While directly analyzing the brain has a number of limitations, checking retinal structure and function can be possible using minimally or non-invasive procedures. This suggests that the health status of the brain could be indirectly assessed through the eyes and diagnostic screening of brain diseases could become more efficient.

In Dr. Leinonen's experiments, he used a procedure called electroretinography (ERG) and visual evoked potentials (VEP) to identify changes in retinal functions. Using a mouse model with Huntington's disease (HD), Dr. Leinonen found changes in day and color vision while the animal was in its pre-symptomatic phase.

The retinal structure was somewhat normal even in the advanced state of the disease. However, a collection of toxic mutated huntingtin protein was seen all over the diseased mouse's retina. Science Newsline reported that although the retinopathy in the model mice showed an exaggerated result compared to human HD patients, the findings was also directed to the patient data which revealed impaired color vision but no clear-cut anatomical retinopathy.

It is also important to note that researchers found abnormalities in night vision in a mouse model with Alzheimer's disease, reported UPI. They discovered that the rod-mediated inner retinal, which responses to dim light flashes, were quicker in diseased mice than in their wild-type controls. The observation may be explained by impaired cholinergic neurotransmission that is also one of the reasons for the deterioration of memory in AD.

Basically, Dr. Leinonen's findings contribute to the growing evidence that pathological changes in the retina are linked to the central nervous system, noticing that visual impairment was the fastest progressive symptom in two of the models tested.