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Could OCT hold the key to kidney disease monitoring?

 

OCT imaging is showing promise as a new way to non-invasively monitor kidney disease – with a study also demonstrating how these retinal changes are reversed when kidney function is restored by transplantation.

Recently in Nature Communications, University of Edinburgh researchers conducted four prospective studies of 112 patients with pre-dialysis chronic kidney disease (including those with a kidney transplant), 92 patients with kidney failure undergoing kidney transplantation, 22 living kidney donors, and 86 healthy volunteers.

A key insight from the study showed patients with chronic kidney disease had thinner retinas on average compared with healthy volunteers, highlighting the potential of OCT imaging in monitoring patients who often face more invasive methods to track their disease.

“Microvascular changes are important in chronic kidney disease development and progression. Currently, these can only be assessed reliably through kidney biopsy, which is invasive. Interval kidney biopsy, to assess microvascular changes over time and in response to therapies, is also impractical. Thus, there is an urgent unmet need for novel biomarkers that will sensitively and specifically track kidney injury, reliably demonstrate response to treatments, and predict longer-term outcomes,” the researchers noted.

“The kidney and eye are structurally and functionally similar meaning that diseases may present similarly and via common pathways in both organs.”

The study noted OCT’s potential due to its non-invasive nature, and its ability to cross-sectionally image the eye. It’s also available in most high street opticians and recent advances have helped identify specific cell layers within the retina in high resolution, as well as deeper structures such as the choroid.

The study’s major findings included:

  1. Retinal and choroidal thinning occurs in chronic kidney disease and progresses as kidney function declines;
  2. these changes in OCT metrics are reversed when kidney function is restored by kidney transplantation;
  3. healthy individuals who donate a kidney and lose kidney function gradually develop choroidal thinning and;
  4. in those with chronic kidney disease, a thinner retina and choroid seen on a single point-in-time OCT scan independently associate with future estimated decline in estimated Glomerular Filtration Rate (eGFR – showing how well the kidneys are filtering).

“These observations highlight the potential for OCT metrics to act as a non-invasive monitoring and prognostic biomarker of kidney injury,” the researchers concluded.

“The greater the severity of kidney disease (reflected by a lower eGFR), the thinner the retina and choroid. Notably, this was independent of age, a recognised, important contributor to chorioretinal thinning. We also found that the retinal thinning in patients with chronic kidney disease was more marked in the central retina, compared with the peripheral scan regions.”

More reading

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