ObjectiveTo observe the long-term effects of anti-vascular endothelial growth factor (VEGF) drug initiation combined with dexamethasone intravitreal implant (DEX) on the structural integrity of the outer macular region of the eye in patients with macular edema (ME) secondary to central retinal vein occlusion (CRVO). MethodsA retrospective clinical study. From February 2018 to August 2022, 54 patients diagnosed with CRVO combined with ME (CRVO-ME) in Department of Ophthalmology of Central Theater Command General Hospital were included in the study. Among them, there were 30 males and 24 females, all with monocular disease. According to different treatment regiments, patients were divided into anti-VEGF and DEX combination therapy group (initial combination group), anti-VEGF drug monotherapy group (monotherapy group) with 21 eyes and 33 eyes, respectively. Best corrected visual acuity (BCVA), optical coherence tomography (OCT) examination were performed in all eyes. The thickness of foveal retina (CRT) and the deficiency length of outer membrane (ELM), ellipsoid band (EZ) and chimaera band (IZ) in the 1 mm macular area were measured by OCT. The initiating combination group was treated with anti-VEGF agents or DEX as assessed on demand (PRN) after the combination therapy, and the monotherapy group received 3+PRN regimen. Relevant examinations were performed at 1 (V1), 6 (V6), 12 (V12) months and observation cut-off or the last visit (Vf) after treatment using the same equipment before treatment. The deletion length of ELM, EZ and IZ in V1, V6, V12 and Vf after treatment were compared between the two groups. Repeated measurement ANOVA was used to compare BCVA, CRT and deletion length of ELM, EZ and IZ at different follow-up times. Spearman rank correlation test was used to analyze the correlation between the two groups of continuous variables. ResultsThe follow-up time of patients in the initial combination group and monotherapy group was (18.05±5.66) and (21.90±10.80) months, respectively, with no statistical significance (F=13.430, P=0.229). Compared with baseline, the deletion lengths of ELM, EZ and IZ were significantly improved (F=11.848, 10.880, 29.236), BCVA was increased (F=10.541) and CRT was decreased (F=52.278) in the initial combination group and the monotherapy group at different follow-up times after treatment. The differences were statistically significant (P＜0.001). At V1, EZ and IZ deletion lengths were (344.10±413.03), (593.33±372.96) μm and (354.71±321.75), (604.85±385.77) μm in the initial combination group and monotherapy group, respectively. The improvement of EZ and IZ deletion lengths in the initial combination group was better than that in the single drug group, and the difference was statistically significant (F=5.272, 6.106; P=0.026, 0.017). The CRT of the initial combination group and the monotherapy group were (248.86±59.99) and (314.72±214.91) μm, respectively, and the CRT of the initial combination group was significantly lower than that of the monotherapy group, with statistical significance (F=6.102, P=0.017). At V6, V12 and Vf, the deletion length of ELM, EZ and IZ and BCVA and CRT showed no statistical significance (P＞0.05). Correlation analysis showed that ELM, EZ, IZ were positively correlated with BCVA and CRT in the initial combination group and monotherapy group (P＜0.001). In V6, V12 and Vf, the number of anti-VEGF drug injections in the initial combination group and monotherapy group was (2.67±1.32), (4.43±2.27), (6.05±3.51), (4.58±0.90), (7.33±1.93), (11.33±6.10) times, respectively. The number of injections in the initial combination group was significantly lower than that in the monotherapy group, and the difference was statistically significant (F=5.150, 0.646, 3.433; P＜0.001). ConclusionsThe improvement of BCVA and CRT in the initial combination group is similar to that in the monotherapy group. Compared with the monotherapy group, EZ and IZ deletion are improved more significantly in the initial combination group, and CRT decreased more rapidly and significantly. The initial combination group receives fewer anti-VEGF injections than the monocular group.