Short-Term Results of Dexamethasone Intravitreal Implant in Patients with Persistent Diabetic Macular Edema

To evaluate the effectiveness and safety of combining intravitreal dexamethasone implant (IVDI) and ranibizumab in patients with persistent diabetic macular edema (DME) who are unresponsive to multiple treatments.

This study included 36 eyes from 28 patients. Eligibility criteria were persistent DME with a central macular thickness (CMT) ≥300 µm despite ≥3 consecutive monthly intravitreal anti-VEGF injections and/or focal/grid laser photocoagulation at least 6 weeks before enrolment. Patients with <50% reduction in CMT or <2-line improvement in best-corrected visual acuity (BCVA) after prior treatments were enrolled. All eyes received a single IVDI and were followed monthly for 6 months. If BCVA decreased by ≥5 ETDRS letters or CMT increased by ≥100 µm, additional intravitreal ranibizumab (IVRB) was permitted. The primary outcomes were BCVA, intraocular pressure (IOP), and CMT.

The baseline mean BCVA was 0.65 ± 0.30 logMAR, mean CMT 501.2 ± 145.9 µm, and mean IOP 16.2 ± 2.5 mmHg. BCVA improved significantly to 0.53 ± 0.27 logMAR at month 1 (P = 0.002), 0.46 ± 0.27 at month 2 (P < 0.001), and 0.54 ± 0.31 at month 3 (P = 0.014). Correspondingly, CMT decreased to 293.7 ± 77.6 µm, 273.3 ± 51.3 µm, and 351.0 ± 112.3 µm (all P < 0.001). DME recurred in 16-17 eyes between months 3 and 5, requiring additional IVRB. Following retreatment, BCVA remained stable (0.50-0.54 logMAR, P ≤ 0.029) and CMT persisted between 353 and 382 µm (P ≤ 0.001) through month 6. IOP increased significantly during the first 2 months but returned to baseline thereafter.

IVDI demonstrated substantial enhancement in patients with chronic persistent DME who were resistant to different treatments, with peak efficacy observed in the second month. Therefore, it may be considered an alternative therapeutic choice.