Correlation between renal function and peripapillary choroidal thickness in treatment naïve diabetic eyes using SS-OCT

Purpose To investigate the association between the estimated glomerular filtration rate (eGFR) and peripapillary choroidal thickness (pCT) and retinal nerve fibre layer (pRNFL) thickness in diabetic patients by using swept-source optical coherence tomography (SS-OCT). Methods Ocular treatment-naïve patients with type 2 diabetes mellitus registered in the community health system in Guangzhou, China were recruited to participate in this prospective cross-sectional study. The eGFR was determined using the Xiangya formula, and the renal function was categorized into non-chronic kidney disease (non-CKD), mild CKD, and moderate to severe CKD (MS-CKD) according to the guidelines. The pCT and pRNFL thicknesses at 12 o’clock were obtained using a SS-OCT by a circular scan with a diameter of 3.4 mm centring on the optic nerve head, and the data from only one eye in each patient were used. Results This study included 1,408 diabetic patients, with a mean age of 64.4±7.8 years. The average pCT decreased with renal function deterioration, with 126.0 μm ± 58.0 μm for non-CKD, 112.0 μm ± 51.2 μm for mild CKD and 71.0μm ± 22.9 μm for MS-CKD, respectively (P<0.001). The pCT was found to be significantly thinner in CKD patients in all quadrantes (P < 0.05 in all regions) with the exception of the inferior quadrant, and the average pCT was positively correlated with eGFR (β = 0.3, 95%CI = 0.0 to 0.6, p = 0.021) after making adjustments for other factors. The pRNFL thickness in the nasal quadrant was significantly reduced in patients with CKD, and pRNFL thickness was positively correlated with eGFR (β = 0.1, 95%CI = 0.0-0.2, p = 0.009) after adjusting for other factors. Conclusion Impaired renal function was associated with a reduction of pCT and pRNFL thickness in patients with type 2 diabetes. The measurement of pCT and pRNFL may provide additional information for predicting renal impairment.