Initial Clinical Experience With the CyPass Micro-Stent
Journal of Glaucoma
The CyPass Micro-Stent (Transcend Medical) is a novel device implanted in the supraciliary space in conjunction with cataract surgery in order to facilitate suprachoroidal aqueous outflow and reduce intraocular pressure (IOP). Hoeh et al. evaluated the device’s efficacy and safety and found that it yielded a reduction in IOP and in medication use. The procedure is ab interno and minimally invasive.
The study included 142 patients with open-angle glaucoma and cataract who underwent a combined procedure of phacoemulsification, intraocular lens implantation, and stent implantation. Patients were divided into 2 cohorts: those with baseline medicated IOP ≥21 mm Hg (group 1) and those with medicated IOP <21 mm Hg (group 2). The main outcome measures were adverse events, changes in IOP, and the number of IOP-lowering medications required.
Mean (SD) follow-up was 294 (121) days, and no serious intraoperative or postoperative complications occurred. Group 1 had a 35% decrease in mean IOP and a 49% reduction in mean glaucoma medication usage, and group 2 had a 75% reduction in mean medication usage while maintaining a mean IOP of <21 mm Hg. For all eyes, mean IOP at 12 months was 15.9 ± 3.1 mm Hg (a 14% reduction from overall baseline). There were no sight-threatening intraoperative complications. The most common postoperative adverse event was transient IOP fluctuation during the first 4 weeks after surgery; 14% of eyes had transient early hypotony, but all cases resolved by 1 month.
The researchers concluded that the 1-year safety profile and clinical outcomes from this study indicate that suprachoroidal outflow through this novel implantable device may be a promising approach for glaucoma management.
Phenytoin for Neuroprotection in Acute Optic Neuritis
Published online Jan. 25, 2016
Acute demyelinating optic neuritis (ON) is common among patients with multiple sclerosis and damages the optic nerve and its fibers in the retina. Kapoor et al. studied whether sodium-channel inhibition with phenytoin, an antiseizure drug, might be neuroprotective in ON, and their findings support this concept of neuroprotection.
The researchers conducted a randomized placebo-controlled double-blind phase 2 trial at 2 academic hospitals in the United Kingdom. The study participants ranged in age from 18 to 60, had documented acute ON, and presented within 2 weeks of onset with a visual acuity of 6/9 or worse.
A total of 86 participants were randomly assigned to either oral phenytoin (42) or placebo (44) for 3 months. Patients assigned to phenytoin received a loading dose of 15 mg/kg of body weight for 3 days, after which 29 of them were assigned to a maintenance dosage of 4 mg/kg per day and 13 to 6 mg/kg per day (depending on date of assignment). The participants were also stratified by time from onset, medical center, previous multiple sclerosis diagnosis, use of disease-modifying treatment, and use of corticosteroids for acute ON.
The primary study outcome was retinal nerve fiber layer (RNFL) thickness in the affected eye at 6 months. This was adjusted for fellow-eye RNFL thickness at baseline and analyzed in a modified intention-to-treat population of all randomized participants who were followed up at 6 months. The investigators analyzed safety in the entire population, including 5 subjects who were lost to follow-up.
The mean RNFL thickness in the affected eye at 6 months was 81.46 μm in the phenytoin group versus 74.29 μm in the placebo group. This finding corresponds to a 30% reduction in the extent of RNFL loss with phenytoin compared to placebo. The most common adverse event was skin rash, which led to withdrawal of 10 patients from the phenytoin group.
The researchers concluded that their results support the concept of neuroprotection using phenytoin to inhibit voltage-gated sodium channels in patients with acute ON results and should encourage larger, phase 3 trials of sodium-channel inhibitors in ON and other relapses of multiple sclerosis.
3-Year Follow-up of a Novel Aqueous Humor MicroShunt
Journal of Glaucoma
Batlle et al. conducted an observational study to determine the safety and efficacy of filtering surgery with a microlumen aqueous drainage device (InnFocus MicroShunt) implanted alone or in combination with phacoemulsification. They found that most subjects attained control of intraocular pressure (IOP) in the low teens for up to 3 years.
This single-site prospective nonrandomized study followed 23 eyes that had failed to achieve IOP control on maximally tolerated glaucoma medication. Fourteen patients underwent implantation alone, while 9 received the device in connection with cataract surgery. Prespecified outcome measures included IOP control, with and without supplemental medication; success rate; medication use; and adverse events.
The soft microlumen tube device was implanted ab externo, with application of mitomycin C, via a 3-mm-long needle tract under the limbus to allow aqueous drainage from the anterior chamber to the scleral surface. This device obviates the need for the scleral flap, sclerostomy, iridotomy, and tensioning sutures used in trabeculectomy. The researchers hypothesized that eliminating these aspects of surgery would reduce scar formation within the bleb as well as inflammation in the anterior chamber and, further, might reduce cataract progression.
The mean percent reduction in IOP from baseline (mean IOP, 23.8 ± 5.3 mm Hg) to 3 years was 53% (mean IOP, 10.7 ± 3.5 mm Hg). The researchers added that this outcome was similar between patients having device implantation alone or in combination with phacoemulsification/IOL implantation. The most common complications were transient hypotony (13%) and transient choroidal effusion (8.7%); all resolved spontaneously.
The researchers noted that this small observational study was not powered or randomized to provide conclusive results on its effectiveness in relation to more conventional procedures such as trabeculectomy. However, the data did provide a level of confidence to proceed to larger controlled studies, which are now under way.
Other Journals summaries are written by Marianne Doran and edited by Deepak P. Edward, MD.
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