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Implantation in the eye of the port delivery system loaded with a bolus of the antivascular endothelial growth factor ranibizumab was associated with similar improvements in visual acuity after 2 years as intravitreal injections with ranibizumab in people with diabetic macular edema, results of a subset analysis of a phase 3 trial have shown.

However, anatomical improvements were more profound in the eyes treated with the port system, and they did not progress onto proliferative diabetic retinopathy or have any reports of endophthalmitis, whereas a portion of the injected eyes did, Jordan Graff, MD, reported at the American Society of Retina Specialists (ASRS) 2025 Annual Meeting in Long Beach, California.

“The port delivery system provides excellent pharmacokinetics and disease control with vision comparable to monthly injection and a reduction in edema that was superior to an idealized standard-of-care injection model,” Graff, a vitreoretinal surgeon at Barnet Dulaney Perkins Eye Center in Phoenix, told Medscape Medical News. “When we looked at complicating factors, we found that the safety outcome signals were essentially equal,” he added.

Study Results

The subset analysis included 241 patients with diabetic macular edema in both eyes from the phase 3 Pagoda trial. In this subset, the participants had the port system implanted in the eye with worse visual acuity and central subfield thickness, an anatomical measure of edema in the eye based on optical coherence tomography. The other eye, referred to as the fellow eye, was treated with intravitreal injections of ranibizumab on the basis of the clinician’s discretion.

The port system is an implant about the size of a grain of rice, which is inserted into the eye. It consists of a reservoir designed to be filled with 0.2 mL of 100 mg/mL ranibizumab by injection. The implant releases the drug into the eye over 6 months for diabetic macular edema and neovascular age-related macular edema, and over 9 months for diabetic retinopathy. Participants in the Pagoda trial received the implant after 4 monthly loading doses of ranibizumab. The FDA approved the implant in February 2022.

In the subset analysis, the eyes with the port system received on average nine treatments over 2 years, including the four loading doses, and one initial and  four refills. The fellow eyes received 12 injections, Graff reported in presenting the results.

Visual acuity improvements were similar in both groups, Graff said. The eyes with the port implants improved from 64.2 ETRDS letters at entry to 74.3 at 2 years, about 20/50 to 20/32 in terms of Snellen visual acuity; the fellow eyes from 69.5 to 75.2 letters (20/40 to 20/32 Snellen).

“What was a surprise and really encouraging to find was that the study eyes with the port, which were the worse eyes, ultimately did better than the eyes that were given ad-lib access to repeated injections in an idealized standard-of-care environment,” Graff told Medscape Medical News.

Central subfield thickness in the port eyes improved from 497.8 microns upon enrollment to 274.5 microns at 2 years, Graff said. For the fellow eyes, the improvement was less dramatic: from 399.1 to 331 microns. The lower the measure, the less extensive the macular edema.

The subset analysis also looked at the proportion of eyes in each group that had more than a two-step improvement in Diabetic Retinopathy Severity Score, a measure of disease activity. Slightly more than half — 50.2% — of the port eyes experienced such an improvement at 2 years vs 31.7% of the fellow eyes.

Graff added the rates of endophthalmitis were similar in both groups: one patient in each. None of the eyes with the port system had an implant dislocation. The rates of vitreous hemorrhage were 10% in the port eyes and 7.5% in the fellow eyes. No eyes in the port group progressed to proliferative diabetic retinopathy, whereas seven of the injection eyes did, he said.

After completing a patient preference questionnaire, 77.5% of participants said they preferred the port to standard injections, Graff said.

“Those points give us the chance to pause as retinal surgeons and think, ‘If I’m not already implementing this in my diabetic patients, I need to give this another look,’” Graff told Medscape Medical News. “We are seeing the collective learnings of using the port delivery platform starting to take effect.”

Study Strengths, Limitations

“The findings reveal that in patients with bilateral diabetic macular edema that the port delivery system actually works quite well,” Raj Maturi, MD, a vitreoretinal surgeon at Midwest Eye Institute and Retina Partners Midwest in Carmel, Indiana, told Medscape Medical News. “The visual acuity gains in this eye compared to the fellow eye that was treated are greater. It’s possible this happened because they started off with worse vision to begin with, but they improved quite a bit nonetheless.”

Maturi noted that the 12 injections the fellow eyes received over the 2-year study was “a little low,” as the label indication recommends monthly injections. Knowing the protocol investigators followed to administer injections to the fellow eye would help to better understand those outcomes, he said.

“An ultimate strength” of the analysis was to use both routes of administration in each patient, Maturi said. “It takes care of all the variables, as it is two eyes of the same subject, so all the systemic variables have essentially been eliminated,” he said.

The fact that the fellow eyes did not improve as much as the port eyes may indicate that the chronic drug exposure the implant provides may be better than the intimate exposure of injections.

“This study helps me promote port delivery system treatment for diabetic retinopathy,” Maturi said.

The Pagoda trial was funded by Genentech. Graff reported having relationships with Regeneron Pharmaceuticals and Genentech. Maturi reported having relationships with AbbVie.

Richard Mark Kirkner is a medical journalist based in Philadelphia.