Saturday, March 25, 2023
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Among the key research presentations:
The vascular endothelial growth-factor (VEGF) inhibitor ranibizumab might be the first major treatment advance in 40 years for proliferative diabetic retinopathy, new research suggests. In the Protocol S study, injections of ranibizumab yielded superior vision over 2 years and reduced the incidence of diabetic macular edema and peripheral visual field loss, compared with panretinal photocoagulation, the standard treatment for proliferative diabetic retinopathy. The study involved 394 eyes from 305 adults treated at 55 centers. "Panretinal photocoagulation has been effective for proliferative diabetic retinopathy over the last 4 decades," but ranibizumab is at least as good for visual acuity at 2 years, said study chair Jeffrey Gross, MD, from the Carolina Retina Center in Columbia, South Carolina. Ranibizumab could become "the preferred initial treatment approach for some patients," he added.
The first phase 3 results for gene therapy in a genetic disease of any kind have been reported for an inherited disease that causes blindness, and they are promising, said researchers speaking here. The study involved 31 children (mean age, 15 years) with visual impairment resulting from Leber's congenital amaurosis, a condition caused by a mutation in the retinal pigment epithelium gene, RPE65, which causes photoreceptor cells to gradually die. The condition typically leads to complete blindness around age 40. One year after a single injection of AAV2-hRPE65v2 (SPK-RPE65, Spark Therapeutics, Inc.), patients were able to easily navigate a poorly lit maze and had improved light sensitivity. "We saw substantial restoration of vision in patients who were progressing toward complete blindness," said study presenter Albert Maguire, MD, from the Scheie Eye Institute in Philadelphia. "This is extraordinarily exciting from my perspective. It's the first time gene therapy has been shown to be beneficial," said Pravin Dugel, MD, from the University of Southern California Keck School of Medicine in Los Angeles.
The sustained and tapered release of dexamethasone to the ocular surface of the eye after cataract surgery significantly reduces pain and inflammation, an analysis of data from two phase 3 trials has shown. The polyethylene glycol-based hydrogel punctal plug (OTX-DP, Ocular Therapeutix), implanted into the distal aspect of the inferior or superior canaliculus after surgery, releases dexamethasone 0.4 mg for about 30 days and dissolves naturally, said Thomas Walters, MD, from Texan Eye in Austin. "The dexamethasone plug was statistically superior at day 8 in both trials for the absence of pain, and significantly superior in the first trial for the absence of anterior chamber cells on day 14," he reported. No safety concerns emerged in either study. Having an implantable steroid with sustained action would be a benefit in clinical practice, said session moderator Mitchell Weikert, MD, from the Baylor College of Medicine in Houston. Alternative methods for delivering drugs perioperatively is "a hot topic," and the dexamethasone plug is just one such approach, he pointed out.
For neovascular age-related macular degeneration and classic-containing lesions, adding 2% squalamine lactate ophthalmic solution (OHR-102, Ohr Pharmaceutical) to ranibizumab increased visual acuity in the phase 2 IMPACT study. There was a mean gain in visual acuity and in the proportion of patients, primarily with classic choroidal neovascularization, with gains of three, four, and five lines, but there was no reduction in the number of ranibizumab injections (the primary end point), reported David Boyer, MD, from the Retina Vitreous Associates Medical Group in Los Angeles. There is a great deal of interest in combination treatments for neovascular age-related macular degeneration, said Pravin Dugel, MD, from Retinal Consultants of Arizona in Phoenix. "The ceiling has been reached with anti-VEGF agents." In the case of squalamine, "we are talking about eye drops, which is very exciting," he said.
A biodegradable sustained-release bimatoprost implant (Bimatoprost SR, Allergan) is safe and effective for glaucoma, and could change the treatment paradigm for the disease, according to investigators involved in a phase 1/2 trial. The implant was developed to address the problem of nonadherence in glaucoma, said Richard Lewis, MD, from Sacramento Eye Consultants in California. And the results are promising: The implant "provided rapid and sustained lowering of intraocular pressure." Dr Lewis reported 6-month interim results on 75 glaucoma patients from the 24-month trial, deemed a Best of AAO poster. The overall reduction in intraocular pressure from baseline to week 16 ranged from 7.2 to 9.5 mm Hg in eyes that received a single implant, which was similar to the mean reduction of 8.4 mm Hg seen in the control eyes. The reduction in intraocular pressure in the implant group was clinically significant out to 6 months (P < .001). And by month 6, more than 70% of the implant eyes had not required topical pressure-lowering rescue medication or a second bimatoprost injection. The issue of how long the implant is effective is still being evaluated.
After patients blinded by retinitis pigmentosa underwent transchoroidal implantation of a subretinal device (Alpha IMS, Retina Implant AG), almost 50% could recognize shapes and details of objects 12 months after implantation, and another 25% could localize them. "These patients were completely blind before this, and now more than half are benefiting from the procedure in their daily life," said Helmut Sachs, MD, from the Städtisches Klinikum Dresden-Friedrichstadt in Germany. In a Merit Poster, Dr Sachs reported visual and surgical safety outcomes in 29 blind patients who received the implant. The subretinal device is internal and only requires a magnet transmitter to be worn close to the ear; no camera is required, unlike the only currently FDA-approved retinal prosthesis. The next quest for the developers is to make the subretinal implant more "biostable," Dr Sachs said. "With time, you get a decrease of function, largely because the chip is attacked by a hostile environment." But already, he pointed out, the next generation of the implant is lasting 5 to 10 years longer.
For patients with refractory glaucoma, the cumulative failure rate at 5 years was lower with the Baerveldt-350 implant (Abbott Medical Optics) than with the Ahmed glaucoma valve (Model FP7, New World Medical), according to 5-year outcomes from the Ahmed Versus Baerveldt (AVB) Study reported by Panos Christakis, MD, an ophthalmology resident at the University of Toronto. Mean intraocular pressure at 5 years was also lower in patients treated with the Baerveldt device, and they required fewer medications. However, the risk for hypotony was higher with the Baerveldt than with the Ahmed device. "Our study provides prospective evidence that both the Ahmed and Baerveldt implants are effective treatments for refractory glaucoma, and there are advantages and disadvantages of each," Dr Christakis said. Session panelist Shelly Gupta Jain, MD, from Ohio State University in Columbus, advised individualizing device selection. "Some of my patients live far away, and I do not want the risk of hypotony. And some patients have extremely high pressure to start with and don't have the flexibility to wait for treatment to work," she explained.
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