Chronic kidney disease has long been tied to eye disorders, including retinopathy, glaucoma, cataracts and vision loss. A team of researchers from China now reports that patients with chronic kidney disease may also exhibit distinct changes in retinal oxygen saturation and vascular diameter compared with healthy patients, which could provide clues for early detection and diagnosis of the renal disease.

The study included 83 patients with chronic kidney disease and 103 healthy individuals. The investigators examined all participants using a noninvasive technology developed in Iceland (Oxymap T1) for measuring the arterial and venous oxygen saturation and the arteriovenous difference in oxygen saturation. Researchers also measured the corresponding retinal vessel diameters of the arterioles and venules and used serum creatinine concentrations to calculate the estimated glomerular filtration rate of patients with chronic kidney disease.

In general, patients with chronic kidney disease had higher arterial oxygen saturation values than healthy individuals (100.15±4.68% vs. 97.14±4.22%) and a significant increase in arterial oxygen saturation in the superior temporal, superior nasal and inferior nasal quadrants.

When comparing venous oxygen saturation, the study found no significant difference between patients with chronic kidney disease (63.66±5.29%) and healthy individuals (62.70±5.27%). Also of note: the arteriovenous difference in oxygen saturation in the kidney disease group (36.49±4.98%) was higher than the controls (34.44±4.76%).

The study found other notable differences as well:

• The retinal arteriole diameter was narrower in patients with kidney disease compared with normal individuals (117.53±14.88μm vs. 126.87±14.98μm).
  
• The arteriovenous ratio was smaller compared with the control (0.71±0.09 vs.0.77±0.09).

Further studies are needed to determine whether such changes play a role in the development of chronic kidney disease, the researchers note.