A short-term retrospective study published in Eye Discovery compared a new “1 + 1 + PRN” sequential regimen to the standard “3 + PRN” anti-VEGF approach for diabetic macular edema (DME). The research was done by teams at the Third Affiliated Hospital of Wenzhou Medical University, the Primasia International Eye Research Institute at the Chinese University of Hong Kong, and collaborators.
What they tested
- “1 + 1 + PRN” group: 1-2 anti-VEGF injections, then a dexamethasone intravitreal implant 4 weeks later, followed by anti-VEGF only as needed.
- “3 + PRN” group: 3 monthly anti-VEGF injections, then anti-VEGF as needed.
- Why try this? Anti-VEGF drugs target VEGF-driven leakage, but DME also involves inflammation. Dexamethasone implants work via a different anti-inflammatory mechanism and release drug slowly, potentially cutting injection frequency.
Study details
- Size: 28 eyes from 23 treatment-naïve patients
- Follow-up: 25 weeks
- Outcomes measured: Best-corrected visual acuity, central macular thickness, hyperreflective foci, and cystic changes in the deep capillary plexus using OCTA
Key findings
- Visual + anatomical results: Both groups showed significant improvements from baseline in vision and retinal thickness. No statistically significant differences between groups, though the “1 + 1 + PRN” group showed a trend toward earlier, more stable visual gains and smoother reduction in central macular thickness.
- Injection burden: Mean injections over 25 weeks were 2.58 for “1 + 1 + PRN” vs 4.94 for “3 + PRN”. Most sequential-group eyes needed only 2-3 injections total.
- Safety: Elevated intraocular pressure occurred in both groups, controlled with topical meds, with no significant difference. No severe adverse events like cataract progression, retinal detachment, vitreous hemorrhage, or endophthalmitis were seen.
Limitations
The authors note this was small, retrospective, non-randomized, and short-term. Treatment was chosen by shared decision-making, not random assignment. Different anti-VEGF agents were used, and not all “1 + 1 + PRN” eyes got the same number of initial anti-VEGF shots.
Takeaway: The “1 + 1 + PRN” approach cut injection frequency nearly in half without clearly compromising early visual or anatomical outcomes at 25 weeks. The results are exploratory — larger, longer randomized trials are needed before this could become a standard option. Fewer injections could mean lower cost, less clinic burden, and reduced treatment anxiety for DME patients.