Correlation between fundus color and retinal microcirculation in type 2 diabetes mellitus patients.

PURPOSE: This study quantified retinal color parameters from fundus photography and integrated microcirculatory metrics from retinal oximetry, optical coherence tomography angiography (OCTA), and color doppler imaging (CDI) to investigate the specific application of fundus color in assessing microcirculation in type 2 diabetic Mellitus (T2DM) patients.

METHODS

Participants underwent fundus photography, retinal oximetry, OCTA, and CDI. Fundus color features were extracted using Photoshop and Python based on Red-Green-Blue (RGB), Commission Internationale de l'Éclairage Color Space (Lab), and Hue-Saturation-Value (HSV) models. Microvascular parameters were assessed via oximetry, OCTA, and CDI. Data were analyzed with SPSS 24.0.

RESULTS

Fundus color parameter RGB-B correlated positively with age (r = 0.221, P = 0.033, Q = 0.297), venous oxygen saturation (SvO2) (r = 0.404, P = 0.000, Q = 0.000), diameter of vein (D-V) (r = 0.246, P = 0.018, Q = 0.197), and negatively with arteriovenous difference (A-V) (r=-0.385, P=0.000, Q=0.000). Lab-a correlated positively with age (r = 0.392, P= 0.000, Q = 0.000) and disease duration (r = 0.357, P= 0.000, Q = 0.000), and negatively with end diastolic velocity of the central retinal artery (r=-0.206, P = 0.047, Q = 0.378). Lab-b correlated positively with foveal density-300 (FD-300) (r = 0.285, P = 0.006, Q = 0.092). HSV-H correlated positively with age (r = 0.513, P= 0.000, Q = 0.000), A-V (r = 0.313, P = 0.002, Q = 0.034) and FD-300 (r = 0.237, P = 0.022, Q = 0.224), and negatively with disease duration (r=-0.409, P= 0.000, Q = 0.000), Glycated Hemoglobin A1c (HbA1c) (r=-0.252, P = 0.015, Q = 0.177), and SvO2 (r=-0.297, P = 0.007, Q = 0.097). HSV-S correlated negatively with age (r=-0.229, P = 0.027, Q = 0.258), SvO2 (r=-0.412, P= 0.000, Q = 0.000), and d-V (r=-0.215, P = 0.038, Q = 0.323), and positively with A-V (r = 0.387, P= 0.000, Q = 0.000) and FD-300 (r = 0.270, P = 0.009, Q = 0.115).

CONCLUSIONS

Quantitative fundus color may serve as a non-invasive potential surrogate marker for systemic state and retinal microcirculatory status of T2DM.