Abstract： Objective:To explore the positive rate of scanning laser ophthalmoscope in the retromode (RM-SLO) in different types of diabetic macular edema (DME), and to analyze its correlation with foveal thickness (CMT) and macular volume.Methods:From March to May 2021, 40 patients (65 eyes) were diagnosed as DME by fundus examination combined with optical coherence tomography (OCT) in Affiliated Eye Hospital of Wenzhou Medical University at Hangzhou were included in the study. All eyes underwent best corrected visual acuity (BCVA), OCT and RM-SLO fundus imaging examinations, 47 eyes underwent fluorescein fundus angiography (FFA) examination. RM-SLO fundus imaging examinations were performed with Mirante SLO, including retro mode illumination deviated right (RMDR) and retro mode illumination deviated left (RMDL). If one or more of the RMDR and RMDL of the examined patient can identify macular edema, RM-SLO was considered to be able to identify macular edema. The macular volume at CMT and 6 mm from the fovea was measured by OCT software. DME were divided into 3 types based on OCT images: diffuse retinal thinkening (DRT) type; cystoid macular edema(CME) type; serous retinal detachment (SRD) type, focal leakage type, diffuse leakage type and diffuse cystic leakage type. The consistency of RMDR and RMDL in the diagnosis of DME in RM-SLO fundus imaging was evaluated, as well as their positive rate in different classifications of DME. The correlation between the detection of macular edema by RM-SLO and the DME type, CMT and foveal volume, and the correlation between BCVA and edema type, CMT and macular volume were analyzed.Results:Among 65 eyes, the positive rates of RMDR and RMDL fundus imaging to detect DME were 46 (70.77%, 46/65) and 48 (73.85%, 48/65), respectively. There was good consistency in identifying DME (Kappa value=0.770; P<0.001). The positive rates of RMDR and RMDL fundus imaging DRT, CME and SRD type of DME were 42.11% (8/19), 57.89% (11/19), 77.78% (28/36), 77.78% (28/36), 100.00% (10/10), 90.00% (9/10), respectively. In the FFA classification of them, the positive rates of focal leakage, diffuse leakage and diffuse cystic leakage were 68.75% (11/16), 62.50% (10/16), 68.00% (17/25), 76.00% (19/25), 100.00% (6/6), 100.00% (6/6), respectively. The results of Spearman correlation analysis showed that whether RM-SLO could identify DME was associated with CMT and OCT classification ( r=0.310, 0.365; P=0.120, 0.003); there was no correlation between FFA classification and macular volume ( r=0.113, 0.117; P=0.449, 0.352). BCVA was correlated with CMT and macular volume ( r=0.307, 0.269; P=0.013, 0.030), however, there was no significant correlation with OCT type, angiographic type ( r=0.051, 0.175; P=0.684, 0.240). Conclusion:The diagnostic agreement of DME are good between RMDR, RMDL of RM-SLO image. DME of DRT type and patients with smaller CMT in OCT are difficult to identified by RM-SLO fundus imaging.