From the editors of Review of Ophthalmology:
MAY IS HEALTHY VISION MONTH
In this issue: (click heading to view article)
Improved Blood Flow on OCTA After Panretinal Photocoagulation for PDR
Researchers evaluated macular microvascular changes in eyes with proliferative diabetic retinopathy following panretinal photocoagulation. Using optical coherence tomography angiography, researchers prospectively studied 10 eyes of 10 subjects with high risk PDR immediately before, one month, and three to six months following PRP, using a 3 x 3 mm OCTA scan at each visit.
The following parameters were calculated for the superficial, middle (MCP) and deep capillary plexuses (DCP): parafoveal vessel density; adjusted flow index (AFI); and percent area of non-perfusion (PAN). Researchers also evaluated parafoveal SCP vessel length density. They performed univariate and multivariable statistics, adjusting for age and signal strength. To model the hemodynamic effect of PRP, they also presented a mathematical model based on electrical circuits. Here were some of the findings:
• No significant difference was detected for the vascular density parameters following PRP, except for decreased density at the MCP at the latest time point in the adjusted multivariable model.
• PAN, a metric of non-perfusion adjusted for noise, as well as AFI, a surrogate metric of blood flow, showed significant increase at all capillary levels in the adjusted model.
• The mathematical model explained how PRP would increase macular blood flow.
Researchers wrote that, using OCTA, they found an overall increase in the flow metrics of all capillary layers in the macula following PRP, unrelated to macular edema or thickening, and in line with the mathematical model.
SOURCE: Fawzi AA, Fayed AE, Linsenmeier RA, et al. Improved macular capillary flow on optical coherence tomography angiography after panretinal photocoagulation for proliferative diabetic retinopathy. Am J Ophthalmol 2019; May 9. [Epub ahead of print].
DSAEK vs. DMEK in the Treatment of Failed Penetrating Keratoplasty
Investigators compared the outcomes of Descemet’s stripping automated endothelial keratoplasty with Descemet’s membrane endothelial keratoplasty for the treatment of failed penetrating keratoplasty, as part of a retrospective chart review of individuals with failed PKP who underwent DSAEK or DMEK.
The median follow-up time for both groups was 28 months (range: six to 116 months). Data collection included demographic characteristics, number of previous corneal transplants, previous glaucoma surgeries, best-corrected visual acuity, endothelial cell density, graft detachment and rebubble rate, rejection episodes and graft failure.
Twenty-eight eyes in the DMEK group, and 24 eyes in the DSAEK group were included in the analysis. Here were some of the findings:
• Forty-three percent of eyes in the DMEK group, and 50 percent of eyes in the DSAEK group had to be regrafted because of failure (p=0.80).
• The most common reason for failure was persistent graft detachment (58 percent) in the DMEK group and secondary failure (58 percent) in the DSAEK group; hence, the time between endothelial keratoplasty and graft failure differed significantly between the groups (p=0.02).
• Six eyes (21 percent) in the DMEK group, and seven eyes (29 percent) in the DSAEK group developed graft rejection (p=0.39).
• Rejection was the cause of failure in 67 percent in the DMEK group, and 71 percent in the DSAEK groups.
• The BCVA six months after surgery was better in the DMEK group compared with the DSAEK group (p=0.051).
Investigators concluded that both DSAEK and DMEK have a role in treating PKP failure. They added that primary failure due to persistent graft detachment was significantly higher in the DMEK group, although the overall failure rate in the medium term was similar.
SOURCE: Bahar I, Kaiserman, McAllum P, et al. Comparison of posterior lamellar keratoplasty techniques to penetrating keratoplasty. Ophthalmology 2008;115:9:1525-33.
Findings in a Large Cohort of Chinese Patients with Suspected RP
Researchers characterized the genetic landscape of individuals with suspected retinitis pigmentosa in the Chinese population, as part of a cohort study. A total of 1,243 individuals of Chinese origin with clinically suspected RP and their available family members (n=2,701) were recruited.
All individuals and available family members were screened using multigene panel testing (including 586 eye disease-associated genes), followed by clinical variant interpretation.
Main outcome measures included diagnostic yield, the 17 most commonly implicated genes, age at onset, de novo mutations and clinical usefulness of genetic testing.
Overall, 72.08 percent of individuals received a molecular diagnosis, and the 17 top genes covered 75.63 percent of diagnostic cases. Here were some of the findings:
• Diagnostic yield was higher among individuals in the early-onset subgroup (≤5 years old, 79.58 percent) than in the childhood or adolescence-onset subgroup (6 to 16 years old, 73.74 percent) and late-onset subgroup (≥17 years old, 65.99 percent).
• Moreover, different genes were associated with different onset ages, and subgroups with different onset ages showed a diverse mutation spectrum.
• Only 11 de novo mutations (3.18 percent) were identified.
• Furthermore, 16.84 percent of individuals who received a molecular diagnosis had refinement of the initial clinical diagnoses, and the remaining 83.16 percent received definite genetic subtypes of RP.
Researchers wrote that genetic testing improved the chance to establish a precise diagnosis, identified features not previously determined and enabled a more accurate refinement of the risk to family members. They added that their results not only expanded the existing genotypic spectrum, but also served as an efficient reference for the design of panel-based genetic diagnostic testing and genetic counseling for individuals with suspected RP in China.
Source: Gao FJ, Li JK, Chen H, et al. Genetic and clinical findings in a large cohort of Chinese patients with suspected retinitis pigmentosa. Ophthalmology 2019; May 1. [Epub ahead of print].
Researchers aimed to present a modified surgical technique for canaloplasty with the Stegmann Canal Expander that avoids the need for lamellar scleral dissection. Three of the authors have a financial interest in the device or its maker, Ophthalmos (Schaffhausen, Switzerland).
After limbal peritomy of the conjunctiva, the sclera wasn’t dissected in the classic lamellar fashion with superficial and deep scleral flaps but was successively ‘scratched’ down by radial incision until Schlemm’s canal was opened (trench cut). Following canal opening and viscodilation with a microcannula and sodium hyaluronate, one canal expander was implanted on either side of the canal ostia and the scleral incision was closed watertight.
Twenty-seven eyes with primary open-angle glaucoma consecutively underwent surgical procedures using this modified technique. Here were some of the findings:
• In all eyes, SC was successively opened, but exposure of the choroid and rupture of trabeculo-Descemet’s membrane with iris prolapse or filtering blebs wasn’t found.
• Adverse events included trimming the expander in one eye for incomplete implantation during surgery and transient microhyphema in five eyes post-surgery.
• Mean intraocular pressure was 31.9 ±6 mmHg before surgery, and 14 ± 2.5 mmHg six months and 15.2 ±1.95 mmHg 12 months after surgery.
Scientists concluded that the flap-sparing, trench-cut incision technique might reduce the risk of complications in canaloplasty with the Stegmann Canal Expander.
SOURCE: Grieshaber MC, Pienaar A, Stegmann R, et al. Flap-sparing canaloplasty: A modified approach to Schlemm's canal. Graefes Arch Clin Exp Ophthalmol 2019; May 6. [Epub ahead of print].
FDA Approves Eylea Injection for Diabetic Retinopathy
Regeneron Pharmaceuticals announced that the FDA approved the Eylea (aflibercept) injection to treat all stages of diabetic retinopathy. Eylea is the only vascular endothelial growth factor inhibitor approved with two dosing options for DR, enabling doctors to customize treatment to their patients' needs, Regeneron says. In DR, Eylea may be dosed every eight weeks following five initial monthly injections, or every four weeks. Read more.
Sydnexis Enrolls First Patients in Phase III Myopia STAAR Study
Sydnexis announced that the first patients were successfully dosed in a Phase III multicenter trial of SYD-101, following FDA clearance of Sydnexis’ IND in April. Sydnexis’ STAAR Study will be the largest myopia study initiated to date with more than 800 patients, the company says. In a placebo-controlled trial the STAAR Study will test the safety and efficacy of two dosage strengths of SYD-101, the company’s patented investigational drug, as a first-line therapy to slow the rate of myopic progression in children. Read more.
Ping An Completes Trials for First Intelligent OCT Retinal Disease Screening System
Ping An Insurance Company of China announced that its technology arm completed a prospective, multicenter clinical trial for what it deems the world's first intelligent optical coherence tomography retinal disease screening system that integrates an OCT with artificial intelligence lesion detection software. The system will be jointly developed with Optovue. Read more.
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