Retina swelling shows brain damage

The retina is a tissue lining the inner wall of the eye. The sensory cells, namely the rods and cones, of the retina pick up electrical signals from when the light hits the eyes, thereby allowing us to see the world.

Recent studies, though, suggests that the retina can serve a broader function. Hopkins researchers found that the retina is capable of revealing the condition of the brain and indicating signs of disease.

The studies focused on detecting signs of multiple sclerosis (MS) through retinal scans. The analysis indicates that signs of the disease can be observed through these scans. Furthermore, it is possible to spot the progress of the disease.

The process requires the use of optical coherence tomography (OCT), which targets the nerves inside the eye. Near-infrared lights are used to produce three dimensional images. The detailed pictures are then analyzed using a software co-developed by Peter Calabresi, a researcher and professor at Hopkins School of Medicine.

The processed data reveals the thickness of the retina and any inflammation occurring in the eye. The correlation between multiple sclerosis and the retina’s condition is apparent from comparing MRI images of the brains of MS patients and the OCT of their retina: as the brain suffers more inflammation, so does the retina. Researchers are confident that retinal scans can become stand-alone indicators of brain injury in the near future.

In addition to the strong relationship between the retina and the brain, the researchers also found pockets of fluids in the retina of some MS patients. This condition, known as microsystic macular edema, predominantly affects older people, the majority of whom are diabetics.

Calabresi states that the appearances of these pockets might warrant a more thorough evaluation of the patient for neural disorders, since it is a clear anomaly.

Signs of MS can also be detected by looking at the peripapillary retinal nerve fiber layer (pRFNL) and the ganglion cell layer (GCL+IPL). These two inner layers of the retina show deterioration in accordance with the damages suffered by the brain. As more gray matter in the brain atrophied, the cell wasting in the two layers increased.

This correlation constitutes a breakthrough, since brain damage is difficult to measure. Because the brain is capable of functioning with slight damage, doctors often cannot gauge whether the damage is severe until the process is irreversible.

However, with the new results produced by retinal scans, doctors can more accurately determine treatments necessary for the patient.

The last important aspect of the study seems to undermine the current knowledge of MS. Popular theory about multiple sclerosis consists of the immune system attacking the myelin sheath that insulates nerves.

However, the deeper layers of the retina do not contain any myelin, but they still show signs of inflammation and swelling in accordance with MS.

This discovery suggests that the immune system of MS patients is attacking other targets in addition to myelin.

With more research in this area, doctors can more effectively treat MS patients afflicted with worsening vision and other symptoms.