Observation of Iris Blood Flow Via OCTA in Diabetic Neovascular Glaucoma

The goal of this observational study is to quantify iris blood flow via non-invasive eye scanning for evaluating ocular lesions in adults aged 18 years and older, including healthy volunteers, patients with type 2 diabetes mellitus (T2DM) without fundus lesions, T2DM patients with diabetic retinopathy (DR), and T2DM patients complicated with both DR and neovascular glaucoma (NVG). The main questions it aims to answer are: * Does iris blood flow fraction at six pupillary quadrants differ significantly among people with different stages of type 2 diabetic eye complications? * Are there quadrant-specific and gender-based differences in iris microcirculation changes caused by diabetic eye diseases? If there is a comparison group: Researchers will compare iris blood flow data from four groups (healthy controls, T2DM without DR, T2DM with DR, T2DM with DR + NVG) to see how iris blood circulation changes as diabetic eye conditions get worse, and test whether iris blood flow indicators can help identify patients with neovascular glaucoma. Participants will complete the following tasks: * Provide basic personal information, past medical history and recent laboratory test results from their routine medical records; * Receive a painless, non-invasive iris OCTA eye scan to capture iris blood flow images at six quadrants around the pupil.