The goal of this study is to evaluate the safety and efficacy of LX111 treatment of DME. This study will enroll participants aged ≥ 18 vears old to receive a single unilateral intravitreal (lVT) injection of LX111 to evaluate its safety and efficacy.

This trial is a prospective, multicenter, dose-ranging trial to evaluate the safety and efficacy of LX111 in participants with DME. The trial will be conducted in two parts: Dose Confirmation and Dose Expansion.

Inclusion Criteria:

1. Willing to sign the informed consent, and willing to attend follow-up visits;
2. Age ≥ 18;
3. Type I or Type II diabetes mellitus with macular thickening secondary to DME involving the center of the fovea;
4. CST ≥ 300 μm in the study eye at Screening;
5. BCVA ETDRS letters between 19 and 73;
6. Participants must have received anti-VEGF therapy within 12 months prior to screening and demonstrated a meaningful response;
7. Male subjects whose partner is a fertile female or female subjects who are fertile, agree to take effective contraceptive measures from the screening period until the last follow-up.

Exclusion Criteria:

1. Active proliferative diabetic retinopathy (PDR);
2. Presence of iris neovascularization in the study eye at Screening;
3. Retinal laser photocoagulation in the study eye within 3 months prior to Screening;
4. Prior gene therapy in the study eye;
5. The study eye has been treated with an intravitreal dexamethasone implant (Ozurdex®) within 6 months prior to Screening.
6. Systemic anti-VEGF treatment within 3 months before Screening;
7. Received an investigational drug, agent, device, or therapy (ocular or non-ocular) in the 3 months (or at least 5 half-lives, whichever is longer) prior to Screening;