Can diabetic macular edema be controlled with fewer injections?

For patients with diabetic macular edema, vision loss is only part of the burden. Repeated intravitreal injections can also create financial pressure, frequent clinic visits, and treatment anxiety, all of which may affect long-term adherence. A new short-term observational study published in Eye Discovery by researchers from the Third Affiliated Hospital of Wenzhou Medical University, the Primasia International Eye Research Institute of the Chinese University of Hong Kong, and collaborating institutions asks whether treatment burden can be reduced without clearly compromising early visual and anatomical outcomes.

The study compared a novel “1+1+PRN” sequential regimen with the conventional “3+PRN” anti-VEGF regimen. In the sequential group, treatment-naïve patients received one or two anti-VEGF injections, followed four weeks later by a dexamethasone intravitreal implant, with later anti-VEGF therapy given as needed. In the conventional group, patients received three consecutive monthly anti-VEGF injections followed by as-needed retreatment.

Diabetic macular edema is driven by multiple mechanisms, including breakdown of the blood–retinal barrier, vascular leakage, chronic inflammation, hypoxia, and structural retinal changes. Anti-VEGF therapy remains a first-line treatment because it directly targets VEGF-mediated vascular permeability. However, not all edema is purely VEGF-driven. Corticosteroids can suppress inflammatory mediators and stabilize vascular leakage through a different mechanism, while the sustained-release dexamethasone implant may reduce the need for frequent injections.

The study included 28 eyes from 23 treatment-naïve patients and followed them for 25 weeks. Both regimens produced significant improvements from baseline in best-corrected visual acuity, central macular thickness, hyperreflective foci, and cystic changes in the deep capillary plexus. No statistically significant differences were found between the two groups for these visual or anatomical outcomes. Still, the “1 + 1 + PRN” group showed a numerically favorable trend, with earlier and more stable visual improvement and a smoother reduction in central macular thickness.

A key practical difference was injection burden. Over 25 weeks, the mean number of intravitreal injections was 2.58 in the “1 + 1 + PRN” group, compared with 4.94 in the “3 + PRN” group. Most eyes in the sequential group were controlled with only two to three injections, representing a substantial reduction in treatment frequency. For patients who require repeated monitoring and long-term care, fewer injections may reduce cost, clinic burden, psychological stress, and barriers to adherence.

The safety findings were also broadly comparable. Elevated intraocular pressure occurred in both groups without a statistically significant difference and was controlled with temporary topical medication. No severe ocular adverse events, such as cataract progression, retinal detachment, vitreous hemorrhage, or endophthalmitis, were observed during the follow-up period.

The findings should be interpreted cautiously. This was a small, retrospective, non-randomized study with short-term follow-up, and treatment allocation was based on shared decision-making rather than random assignment. Different anti-VEGF agents were used, and not all eyes in the sequential group received the same number of anti-VEGF injections before dexamethasone implantation. The results therefore should be viewed as exploratory. Larger, longer, prospective randomized trials will be needed to determine whether the “1 + 1 + PRN” strategy can become a reliable treatment option for diabetic macular edema.

doi: 10.1016/j.edisc.2026.100037

Read the full article: https://doi.org/10.1016/j.edisc.2026.100037

About Eye Discovery

Eye Discovery is an open-access, peer-reviewed international academic journal, with ISSN 3117-4167. It is published quarterly by Elsevier and serves as the official journal of Eye & ENT Hospital of Fudan University, China. 

Eye Discovery  is dedicated to creating a high-end platform for ophthalmologists, scientists, and scholars worldwide to focus on innovative achievements in ophthalmology and interdisciplinary fields, and to promote academic dissemination and exchange.

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From 2026 to 2028, the article processing charge ( APC ) will be waived.