AIM: To study retinal microvascular and microstructural alterations in meibomian gland dysfunction (MGD) in severely obese population using optical coherence tomography angiography (OCTA). METHODS: Twelve MGD patients with severely obese population (PAT group; 24 eyes) and 12 healthy controls (HC group; 24 eyes) were recruited. OCTA images were segmented into five [superior (S), nasal (N), inferior (I), temporal (T), and central foveal (C)] or nine [inner superior (IS), outer superior (OS), inner nasal (IN), outer nasal (ON), inner inferior (II), outer inferior (OI), inner temporal (IT), outer temporal (OT), and C] subregions. The superficial vessel density (SVD), retinal thickness (RT), foveal avascular zone (FAZ) parameters, and retinal volume were measured. RESULTS: Visual acuity was significantly different between two groups (0.8±0.17 in PAT group vs 0.2±0.06 in HC group). SVD was significantly lower in PATs in N, T, OS, IN, OT, and ON. The area under the receiver operating characteristic curve (AUC) for T was 0.961 [95% confidence interval (CI): 0.908 to 1.000], for OS was 0.962 (95%CI: 0.915 to 1.000). RT was significantly lower in PATs in IS, OS, OI, OT, ON, IT, IN, and II. AUC for OT was 0.935 (95%CI: 0.870 to 0.999), for IS was 0.915 (95% CI: 0.838 to 0.992). Angiography results showed significantly lower area and perimeter of FAZ, SVD of the inner retina and both retinal volume and the average volume thickness in the PAT group. CONCLUSION: Vision may be affected in patients with MGD due to changes in retinal microvessels and microstructures. These changes detected by OCTA may be a potential marker for diagnosing MGD in severe obesity.