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NEW YORK CITY -- A form of light therapy led to durable improvement in visual acuity for patients with dry age-related macular degeneration, according to interim results from an ongoing randomized trial.

After 13 months of follow-up, patients randomized to photobiomodulation (PBM) had a 5.5-letter improvement from baseline (P<0.0001), which was statistically superior to the 2-3 letter improvement with sham treatment (P=0.02). More than half of 88 eyes included in the PBM arm had ≥5-letter improvement in best-corrected visual acuity, 26.4% had ≥10-letter improvement, and 5.5% had ≥15-letter improvement.

The PBM group had statistically significant improvement versus the sham group after 1 month and maintained the difference to 13 months. Rates of new geographic atrophy were 9.8% in the sham group and 1.1% with PBM, reported Richard Rosen, MD, of the New York Eye and Ear Infirmary of Mount Sinai in New York City, during the American Society of Retina Specialists (ASRS) meeting.

"Photobiomodulation eyes lost approximately half as many best-corrected visual acuity letters as sham-treated eyes," he said. "There was a nonsignificant increase in central drusen volume in the sham group versus no increase in the PBM group. This was consistent with [previous studies], suggesting a disease-modifying benefit."

PBM involves the use of low-level red-infrared light to stimulate beneficial cellular activity. Targeting cytochrome C, PBM increases energy production, alters signaling modalities, and activates transcription factors, Rosen explained in his introduction. Cytoprotective properties of PBM have been used previously in wound repair.

Rosen reported findings from the multicenter LIGHTSITE III randomized trial involving 100 patients and 148 eyes. Patients underwent PBM or sham treatment three times weekly for 24 months. An interim analysis was planned after 13 weeks.

Gene Therapy Shows Promise in Retinitis Pigmentosa

A small group of patients with retinitis pigmentosa (RP) had improved visual acuity after treatment with an investigational gene therapy.

Six of seven patients had greater than 15 letters of improvement a year after receiving the optogenetics therapy MCO-10. The time required to locate a light source and to navigate a low-light mobility test also decreased. The results supported continued clinical evaluation of the gene therapy in a phase IIb trial of patients with advanced RP.

"The phase IIb clinical study is also in patients with advanced retinitis pigmentosa, randomized to two different doses [of MCO-10] versus a control group," said Peter Kaiser, MD, of the Cleveland Clinic. "The key outcome measure is a different mobility test with a 52-week outcome. The study is fully enrolled and we hope to deliver the results of this study at this meeting."

Optogenetics refers to strategies to turn select neurons on and off with light. The therapy centers on opsins, which are light-sensitive, retinaldehyde-binding proteins. Opsins couple specific photon absorption to molecular signaling that controls on/off ion currents, said Kaiser. The class of therapy includes insertion of genes into cells to confer light responsiveness.

MCO-10 is a mutation-agnostic optogenetic vision-restoration gene therapy employing multicharacteristic opsin (MCO), which is rapidly activated in natural light. An MCO-sensitized retina requires no external stimulation device, and broadband MCO facilitates vision restoration in different-color environments.

Anti-VEGF Delivery System Controls Fluid, Retinal Anatomy

The ranibizumab port delivery system (PDS; Susvimo) controlled fluctuations in retinal thickness and retinal fluid levels comparable to standard monthly injections of ranibizumab (Lucentis), according to updated results from a randomized clinical trial.

About 65-70% of patients in both treatment groups did not have clinically relevant fluctuations (>50 µm) in central subfield thickness (CST) during the 96-week follow-up period of the ARCHWAY trial. Among patients who had fluctuations in CST, the average number was 3.2 in the PDS group and 3.6 in the patients who received standard ranibizumab treatment. The PDS group had a fluctuation score (cumulative CST changes) of 327.2 versus 355.1 with ranibizumab injection.

At 96 weeks, average change in visual acuity associated with CST fluctuations was -2.5 letters with the PDS and -2.6 letters with ranibizumab injection.

A growing body of evidence suggests that the frequency and intensity of CST fluctuations affect visual outcomes. The obvious question is why did patients with fluctuations in the ARCHWAY trial still do "pretty well," said Veeral Sheth, MD, of University Retina and Macula Associates in Oak Forest, Illinois.

"I think the answer is that we didn't see too many fluctuations," he said. "We saw about three to three and a half fluctuations over 24 visits. In other words, they registered a fluctuation of 50 microns or more, three and a half times over those 2 years. So, we're seeing fluctuations, but they're fairly minimal when we do see them."

Similarly, retinal fluid accumulation, another harbinger of worse vision outcomes, was similar between randomized groups in the ARCHWAY trial, reported Aleksandra Rachitskaya, MD, of the Cleveland Clinic. Fewer than 30% of patients in each treatment arm had subretinal fluid (SRF) in the center 1 mm of the retina.

SRF in the center 1 mm was associated with reduced vision in both arms, but in the subgroup of patients with SRF, use of the PDS was associated with a trend toward better maintenance of vision. Patients without SRF had better vision outcomes in both groups, which also was similar between treatment arms.

The results for CST and SRF are consistent with the primary objective of the ARCHWAY trial, which was to achieve vision outcomes with the PDS similar to intravitreal ranibizumab, but with a reduced treatment burden.