By Scott Walter, MD, MSc
The annual meeting of the American Society of Retina Specialists (ASRS) has become one of the most popular and well-attended meetings in our specialty. The four-and-a-half day scientific session is conducted in one auditorium, with rapid fire talks organized by subject matter and moderated by experts in the field. The organizers have skillfully put together a program that’s not only cutting edge and scientifically rigorous, but broadly relevant to a general audience of both academic and community retina specialists.
This year’s meeting was held in my hometown of Vancouver, British Columbia. Meeting attendees were treated to gorgeous weather and scenic vistas from the Vancouver Convention Centre overlooking Coal Harbour and the coastal mountains.
The opening and closing Gala events were held at the Vancouver Aquarium and peak of Grouse Mountain— two unique venues showcasing the city and its spectacular coastline.
Having attended several past ASRS meetings, I was honored to be selected as a first-time speaker for the Ocular Oncology Symposium at this year’s conference. If you missed some or all of the meeting, here are some of my personal highlights.
Two things patients fear most are cancer and blindness. Unfortunately, patients diagnosed with uveal melanoma (a rare form of eye cancer) may have to face both. While local cure rates with current therapies approach 90–95% for patients, vision loss often occurs later as a result of radiation damage to the optic nerve and macula.
My presentation compared two commercially available brachy therapy plaque designs for treating uveal melanoma.
At the outset, circular plaques have been the standard-of-care since the Collaborative Ocular Melanoma Study (COMS). More recently developed Eye Physics (EP) plaques, however, offer a broader array of shapes and even 3D-printed plaque designs. Further, eye Physics (EP) plaques are thinner, with radioactive seeds positioned closer to the sclera in a slotted arrangement to achieve less lateral scatter and steeper dosimetry curves.
In our study, a masked radiation physicist prospectively simulated 63 cases of posterior uveal melanoma with “best fit” dosimetry for both COMS and EP plaques, using multimodal tumor imaging and 3D planning software. We found no overall differences between COMS and EP plaques in tumor coverage or radiation exposure to the macula and optic nerve. However, in a case-by-case analysis, EP plaques were preferred over COMS plaques more often than expected by chance alone.
Another great talk by Dr. Amy Schefler (Retina Consultants of Houston, TX) presented the 6-month results of an early-phase clinical trial investigating a novel targeted therapy (AU-011; Aura Biosciences; Cambridge, MA) for small uveal melanomas. The new drug consists of a viral nanoparticle that binds selectively to cancer cells in the eye. An infrared laser is applied to activate the drug, selectively destroying tumor cells without damaging the overlying retina. Preclinical data in rabbits showed very promising results, but the initial dose escalation studies in human subjects showed a more modest response. Vision was preserved in all patients regardless of tumor location, with some patients showing clinical signs of tumor regression. In theory, it is a very exciting new treatment approach that could one day eliminate blindness as a result of eye cancer treatment.
Medical and Surgical Retina
Vitrectomy (the surgical removal of vitreous gel) is a commonly performed procedure to treat a wide variety of conditions, including retinal detachments, holes, and membranes. The traditional vitrectomy instrumentation consists of a pneumatically-driven guillotine cutter, with maximum cut rates in the range of 5,000–16,000 cuts-per-minute.
The FDA recently approved a new hypersonic vitrectomy system (Vitesse; Bausch+Lomb, Inc., Bridgewater, NJ) with a novel mechanism of action and a theoretical “cut rate” approaching 1.7 million cuts-per-minute. The technology is similar to phacoemulsification (the surgical technique for cataract removal) although the probe size, geometry, and stroke length have been optimized for vitreous removal.
Dr. Kevin Blinder (The Retina Institute; St. Louis, MO) presented the largest case series to date documenting surgical parameters, outcomes, and surgeons’ initial impressions with hypersonic vitrectomy. The study found that lower vacuum settings were required compared to conventional vitrectomy. Two complications of hypersonic vitrectomy were reported, including iatrogenic retinal breaks and scoring of an intraocular lens implant. Most surgeons found hypersonic vitrectomy comparable to conventional vitrectomy, with potential advantages for off-label indications including removal of lens material and silicone oil.
I enjoyed trying hypersonic vitrectomy in a surgical wet-lab hosted in the Exhibition Hall. In my experience, the hypersonic system is quite efficient for vitreous removal, but users may find that much lower vacuum and shorter stroke length settings are required to safely remove vitreous, particularly over detached retina.
Dr. Stanislao Rizzo (Eye Surgery Clinic in Pisa, Italy) presented a new technique for closure of macular holes, using a human amniotic membrane graft introduced into the subretinal space. The results of his initial case series were very encouraging with excellent anatomic outcomes and the majority of patients with refractory macular holes demonstrating significant visual acuity gains. Many in the audience were wowed by Dr. Rizzo’s technique, but it remains to be seen whether these outcomes can be replicated at other centers.
Intravitreal injections are currently the most commonly performed medical procedure in the United States, with retina specialists performing over 4 million injections annually for age-related macular degeneration and diabetic macular edema. Dr. Carl Awh (Tennessee Retina; Nashville, TN) presented preliminary results from the phase 2 LADDER Study, which evaluated the safety and efficacy of a new port delivery system for the administration of an intravitreal drug (Lucentis by Genentech Inc.) in patients with wet macular degeneration. Subjects in three experimental arms of the study received different drug concentrations, demonstrating an incremental dose response. Subjects receiving the highest dose (100mg/mL) had visual acuity and anatomic outcomes similar to patients receiving monthly intravitreal injections.
This has potential to be a disruptive technology in our field, since most intravitreal drugs are currently approved for a 4–8 week dosing interval. By contrast, it appears the port delivery system could increase the median dosing interval to ~15 months, with approximately 80% of patients going 6 months or longer. A phase 3 clinical trial scheduled to begin later this year will serve to establish the safety and efficacy of this new and potentially revolutionary therapeutic strategy.
Dr. Scott Walter is a vitreoretinal surgeon and ocular oncologist practicing in central Connecticut. He is an associate with Retina Consultants, P.C., and an affiliate of Hartford Hospital, Saint Francis Hospital, and the Hartford HealthCare Cancer Institute.