Retinal characteristics*
| Abbreviation | Definition |
| CRAE | central retinal artery equivalent |
| CRVE | central retinal vein equivalent |
| MBCA | Mean of the bifurcation coefficient of arterioles |
| MBCV | Mean of the bifurcation coefficient of venules |
| MVangle | Mean of the bifurcation angles of venules |
| MAangle | Mean of the bifurcation angles of arterioles |
| MAasymmetry | Mean of asymmetry index of arterioles |
| MVasymmetry | Mean of asymmetry index of venules |
| Tortuosity | Tortuosity- assessed by visual grading of one fovea-centred and one disc-centred fundus image from each image |
| Nipping | Arteriole-venous nicking was marked as the narrowing of venule at the crossing point of arteriole |
| Hemorrhage | The presence or absence of hemorrhage |
| Aocclusion | Arteriole occlusions |
| Exudates | The presence or absence of exudates |
| AVR | Arteriole-venule ratio (ie, the ratio of CRAE and CRVE) |