Research uncovers link between eye changes and chronic kidney disease

Patients with kidney disease had thinner retinas and choroids compared to healthy individuals. [iStockphoto]

Chronic Kidney Disease (CKD) is a silent epidemic affecting millions globally. Kidney disease often progresses without symptoms in the early stages.

"By the time symptoms appear, the damage is already done," says Dr Paul Njogu, head of the renal unit at the Kenyatta National Hospital.

But what if there was a way to detect kidney problems earlier and without invasive procedures? Researchers from the University of Edinburgh may have found the answer, and it's right in our eyes.

The team found that changes in the retina and choroid (a layer of blood vessels behind the retina) can provide valuable insights into kidney health. 3D eye scans can reveal vital clues about kidney health that could help to track the progression of CKD, the study discovered.

Using a non-invasive imaging technique called optical coherence tomography (OCT), readily available in most eye clinics, the experts discovered that patients with kidney disease had thinner retinas and choroids compared to healthy individuals.

The connection? It turns out that the eye and kidney share lots of similarities. Both organs depend heavily on tiny blood capillaries to function. In the eye, these delicate vessels nourish the retina, enabling clear vision.

In the kidneys, they create a filtration system to filter and clean the blood. When these capillaries are damaged, due to disease, it also leads to vision problems.

The researchers discovered that the more advanced the kidney disease, the thinner the retina and choroid. This relationship was consistent even after accounting for age, blood pressure, and protein in the urine, known risks in both eye and kidney health.

Interestingly, patients who had undergone kidney transplantation showed a reversal of the retinal and choroidal thinning seen in CKD. In less than a week of receiving a new kidney, their eye structures began to thicken, with continued improvement in the following year.

The researchers observed that kidney donors began showing signs of retinal and choroidal thinning within a year after the donation, despite showing normal kidney function.

This, according to researchers, suggests that eyes could potentially serve as an early warning system, detecting even the most undetectable changes in kidney health long before conventional kidney tests.

"We hope that this research, which shows that the eye is a useful window into the kidney, will help identify more people with early kidney disease - providing an opportunity to start treatments before it progresses," says Dr Neeraj Dhaun, Professor of Nephrology at the University of Edinburgh's Centre for Cardiovascular Science, in a press release.

The findings were published in the journal Nature Communications.