• The Affiliated Eye Hospital of Nanchang University, Jiangxi Eye Hospital, Jiangxi Provincial Key Laboratory of Ophthalmology, Jiangxi Provincial Institute of Ophthalmology and Visual Science, Jiangxi Key Laboratory of Ophthalmology, Jiangxi Provincial Branch of National Clinical Medical Research Center for Otolaryngological Diseases, Jiangxi Provincial Key Laboratory of Vitreoretinal Diseases, Nanchang 330006, China;
You Zhipeng, Email: yzp74@sina.com
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Objective To compare the efficacy of pars plana vitrectomy (PPV) combined with subretinal or intravitreal injection of Conbercept for the treatment of refractory diabetic macular edema (DME). Methods A retrospective case control study. From June 2022 to March 2024, 32 eyes of 32 patients with refractory DME diagnosed at The Affiliated Eye Hospital of Nanchang University were included in the study. All patients had received regular treatment with anti-vascular endothelial growth factor (VEGF) drugs or corticosteroid drugs for at least 5 times, and had undergone focal retinal laser photocoagulation or panretinal laser photocoagulation, the central macular thickness (CMT) persisted or decreased by less than 50 μm. All affected eyes underwent best-corrected visual acuity (BCVA), intraocular pressure, optical coherence tomography (OCT), microperimetry, and laboratory glycated hemoglobin (HbA1c) testing. BCVA was measured using a standard logarithmic visual acuity chart, and converted to the logarithm of the minimum angle of resolution (logMAR) for statistical analysis. CMT was measured using an OCT device. Microperimetry was performed using an MP-3 microperimeter, recording the mean sensitivity (MS) of the retina within a 12° range of the fovea. The affected eyes were treated with 23G PPV combined with internal limiting membrane peeling and either macular subretinal or intravitreal injection of Conbercept, and were divided into subretinal injection group and the intravitreal injection group, each consisting of 16 cases and 16 eyes. The same equipment and methods as before surgery were used for related examinations at 1, 3, and 6 months post-surgery. Changes in BCVA, CMT, and MS were observed and compared, as well as the number of additional anti-VEGF treatments required within 6 months after surgery. Intergroup comparisons were made using independent samples t tests, and repeated measures data were analyzed using repeated measures analysis of variance. Results The age (t=-0.271), gender composition (χ2=0.001), duration of diabetes (Z=-0.868), HbA1c (t=-0.789), intraocular pressure (t=1.689), logMAR BCVA (t=1.393), CMT (t=-0.613), MS (Z=-0.132), and the number of anti-VEGF injections (t=-0.752) between the subretinal injection group and the intravitreal injection group showed no statistically significant differences (P>0.05). The within-subject effects comparison of BCVA, CMT, and MS at 1, 3, and 6 months post-surgery compared to pre-surgery for all affected eyes showed statistically significant differences (F=8.060, 125.722, 39.054; P<0.05). The overall comparison of logMAR BCVA between the subretinal and intravitreal injection groups post-surgery showed no statistically significant difference (F=0.662, P=0.422), however, comparisons of CMT (F=4.540) and MS (F=6.066) showed statistically significant differences (P<0.05). At 1, 3, and 6 months post-surgery, comparisons of logMAR BCVA between the two groups showed no statistically significant differences (t=-0.123, 0.239, 1.087; P>0.05), comparisons of CMT showed statistically significant differences (t=-3.474, -4.832, -2.482; P<0.05), comparisons of MS showed statistically significant differences at 1 and 3 months (t=-2.940, -2.545; P<0.05), but not at 6 months (t=-1.527, P>0.05). At 6 months post-surgery, the number of additional intravitreal anti-VEGF injections required in the subretinal and intravitreal injection groups showed a statistically significant difference (Z=-2.033, P=0.042). During the follow-up period and at the final follow-up, no complications such as injection site bleeding, retinal detachment, vitreous hemorrhage, macular hole, or retinal pigment epithelial tear or atrophy occurred in all affected eyes. Conclusion Compared with intravitreal injection, subretinal injection of Conbercept for the treatment of refractory DME has more advantages in reducing macular edema and improving visual function in the macular area, and also reduces the number of postoperative anti-VEGF drug treatments.

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