New Eye Scan May Detect Kidney Disease Early: Study

New 3D eye scans that are now available can reveal important information about kidney health and could revolutionize how kidney disease is monitored.

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Get your eyes checked for your kidney health? New 3D eye scans that are now available can reveal important information about kidney health and could revolutionize how kidney disease is monitored, new research suggests.

The study, published in Nature Communications, found that the new technology has the potential to support early kidney disease diagnosis. Current screening tests typically can’t detect kidney disease until at least half of kidney function is lost.

How It Works

It all starts with a 3D scan of the retina, which sits in the back of the eye and is responsible for sensing light and sending signals to the brain. Researchers believe that the scans offer a way to predict kidney health because of how similar the eye and kidney are in structure.

By taking 3D images of the retina using optical coherence tomography (OCT), researchers can see how far along a patient’s chronic kidney disease is. Using light waves, the OTC produces a cross-sectional image of the retina, splicing it into individual layers, like phyllo dough.

Researchers then examined images from 204 patients. The patients were at different stages of kidney disease and included individuals who had received transplants. Comparing the patients’ retinal scans to those of 86 healthy individuals, the researchers found that patients with kidney disease had thinner retinas than the healthy control group members.

Specifically, researchers discovered that patients with chronic kidney disease suffered from choroidal thinning. The choroid is the network of blood vessels that supplies nutrition to the posterior layers of the retina. As kidney function declined, retinas also became thinner. However, researchers noted that following a kidney transplant, retinas regained their thickness, reversing the trend. They also observed that patients suffering from the most severe forms of the disease experienced rapid thickening of their retinas after a transplant.

The Kidney–Eye Relationship

While it seems unlikely that optometrists could identify kidney disease through an eye exam, it makes more sense once you understand the biology. Experts have explained that the kidney and eye are similar in both function and structure. Both the glomerulus (the cluster of nerve endings in the kidney where waste products are filtered from blood) and the choroid (the vascular layer between the retina and the sclera—the white outer area of the eyeball—that maintains eye temperature and volume) have vascular networks that are similarly structured. Both organs share the renin-angiotensin-aldosterone system (RAAS), responsible for regulating blood volume, balancing electrolytes, and more.

Because the two organs are so similar in function and structure, researchers have hypothesized that as one starts to deteriorate, the other will begin to deteriorate as well. The disease may originate in the kidney but also establish itself in the eyes, which is why many individuals with chronic kidney failure notice changes in their eyesight, especially as the disease progresses.

A Game-Changer in Kidney Disease Diagnosis

Prior to the 3D scan, there was an unmet need for easy-to-follow biomarkers that reliably track kidney disease, according to the study authors. Chronic kidney disease is a global health problem that continues to grow. Its prevalence increased by 30 percent from 1990 to 2017, according to the study. In the United States alone, 37 million people—or about 15 percent of the population—are estimated to have kidney disease.

Chronic kidney disease typically worsens over time. When left untreated, it can progress to kidney failure and early cardiovascular disease. Patients with pre-dialysis chronic kidney disease more often die from cardiovascular disease before developing kidney failure. Kidney transplantation is often the only treatment that reduces the risk of cardiovascular disease and save lives.

Currently, chronic kidney disease is diagnosed with blood and urine tests and is often found during routine testing. Oftentimes, chronic kidney disease has no symptoms in its early stages. However, the new 3D testing can indicate changes in the retina layers that accompany early-stage chronic kidney disease.

Individuals at risk for chronic kidney disease should undergo regular testing, including people with the following conditions:

• High blood pressure
• Diabetes
• Acute kidney injury, such as sudden damage to the kidneys that causes them to stop working properly
• Cardiovascular disease
• Other conditions of the kidneys, including kidney stones, an enlarged prostate, or lupus
• Family history of chronic kidney disease
• Protein or blood in their urine with no known cause
• Young and with only one kidney
• Taking long-term medications that can affect the kidneys