A Study in People With Diabetic Macular Edema to Test How Well Different Doses of BI 3812465 Are Tolerated

This study is open to adults with diabetic macular edema that involves the center of the eye. The purpose of this study is to find out how well different doses of a medicine called BI 3812465 are tolerated by people with this condition. This is the first time BI 3812465 is given to humans. This study has 2 parts. In Part 1, a small number of participants receive low, medium, or high doses of BI 3812465. The first participants to start the study get low doses of BI 3812465. Participants who start later get higher doses only if the lower doses were tolerated. In Part 2, a larger number of participants are placed into low, medium, or high dose groups. Participants in both parts of the study get BI 3812465 as injections into the back of the eye for a total of 3 eye injections. Participants are in the study for up to 7 months. During this time, they visit the study site 19 times. Where possible, some visits can be done at the participant's home instead of the study site. At study visits, the doctors check the severity of participants' eye condition and note any health problems that could have been caused by BI 3812465.

Inclusion Criteria: All participants, study eye: * Center-involved diabetic macular edema (CI-DME) defined as CST ≥320 μm (micrometers) at Screening, as confirmed on spectral-domain optical coherence tomography (SD-OCT) and confirmed by the central reading center (CRC). * Sufficiently clear ocular media, adequate pupillary dilation, and fixation, to permit quality fundus imaging. All participants: * Diagnosis of diabetes mellitus (DM) type 1 or type 2 under regular treatment, with glycated hemoglobin HbA1c \24 mmHg despite treatment * History of high myopia \>8 diopters in the study eye * Anterior segment and vitreous abnormalities in the study eye that would preclude adequate detection of intraocular inflammation (IOI) or other pathologies * Ocular conditions which, at discretion of the investigator, might interfere with the outcome of the trial. * Previously received ocular gene therapy or cell therapy. * Corticosteroid use locally or systemically within 1 month prior to Screening. * Aphakia or total absence of the posterior capsule. Yttrium aluminum garnet (YAG) laser capsulotomy may be permitted, if performed more than 2 months prior to Day 1. Further exclusion criteria apply.