EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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EW RETINA 114 October 2014 by Sam E. Mansour, MD Some of this data will be made available through the new IRIS (Intelligent Research in Sight) registry sponsored by the American Academy of Ophthalmology, for which we have registered. In addi- tion, we are conducting ongoing tri- als that will provide more informa- tion on using MPLT in conjunction with other treatment modalities. Pattern Scanning Technology I have been performing MPLT on my DME patients for several years and have seen a positive response. However, the nature of subthreshold treatment means that there is no visible indication of what areas have been treated and what remains to be treated. The TxCell Scanning Laser Delivery System (Iridex) coupled with the IQ 532 or IQ 577 laser (Iridex) allows the surgeon to visual- ize the perimeter of the targeted area with the selection of a grid, circle, or triple arc pattern. In addition, the TxCell enhances the surgeon's ability to systematically apply laser therapy in a high-density applica- tion, which is key to the effective- ness of MPLT. In cases of BRVO, it is very help- ful to use TxCell to perform sectoral retinal photocoagulation. I evaluate the fluorescein angiogram and dete - mine where I need to treat based on the distribution of ischemia. I then select the grid pattern and rotate it to efficiently cover the entire area without repetition. This provides a systematic treatment with minimal overlap. I find TxCell-guided MP T so efficient that I use it 90% of the time I perform laser therapy. Case study The benefits of TxCell-guided MP T are easily identified in the following patient. A 61-year-old male present- ed with ischemic BRVO of the right eye associated with macular edema. He previously received two intravitreal injections of Avastin (bevacizumab, Genentech, South San Francisco), with the last injec- tion given on October 15, 2012, and OCT imaging of his eye demon- strated persistent macular edema (Figure 1). I performed MPLT on his right eye on November 9, 2012 suggests that the number of anti- VEGF injections required is reduced when complimented by MPLT. ME following branch retinal vein occlusion (BRVO) is an ex- tremely difficult condition to treat. In a recent pilot study carried out at our clinics, preliminary data suggests that patients with ME secondary to BRVO need significantly fewer anti-VEGF injections when pharmaceutical treatment is complimented by MPLT. I have found from my own ex- perience that the response to MPLT takes more time to develop but has long-lasting effects, versus the nearly immediate response and short-term effects from anti-VEGF therapy. In addition, MPLT tends to be most effective if used when central mean thickness (CMT) is 400 µm or less. A sub-analysis of BRVO patients with ME less than 400 µm of CMT demonstrated a strong efficacy trend indicating that such patients would be ideal candidates for this combi- nation therapy. This is encouraging and further justifies the need for additional evaluation. These intervals allow the tissue to cool, preventing thermal buildup and many of the common side ef- fects of conventional photocoagula- tion. We now know that the retinal pigment epithelium has a role in modulating DME, and stimulation of these cells with MPLT may physi- ologically alter cytokine expression. 3 While MPLT shows certain ad- vantages over CW laser, the standard of care for DME is continuing to evolve as new data emerges regard- ing the efficacy of antivascular e - dothelial growth factor (anti-VEGF) injections. The latest update from the VIBRANT study reinforces previous data comparing CW laser therapy to anti-VEGF injections, showing greater gains in vision from pharmaceutical treatment. 4 However, what is lacking in clin- ical trial data are comparisons that include MPLT rather than CW laser, as well as the optimal integration of pharmacotherapy. The heavy treat- ment burden of monthly anti-VEGF injections has inspired many retina specialists to supplement with laser therapy. Empirical evidence I mproving the delivery of a given treatment and thereby improving patient outcomes is a high priority for any medical professional. Since the initial findings of the Early reatment of Diabetic Retinopathy Study (ETDRS) were released 25 years ago, the therapeutic management of macular edema (ME) has continued to evolve, leading to better clinical outcomes for patients. MicroPulse Laser Therapy The ETDRS established conventional thermal macular photocoagulation as the standard of care for diabetic macular edema (DME) with compli- cations such as visual field loss and expansion of laser scars as necessary side effects. 1 However, recent advances in research and understanding at the cellular level have established MicroPulse Laser Therapy (MPLT, Iridex, Mountain View, Calif.) as a viable alternative. 2 MicroPulse technology breaks up a continuous-wave (CW) laser beam into a series of repetitive, short pulses separated by longer intervals. Redefining oles of laser and pharmacotherapy for macular edema Figure 1: OCT imaging of a patient with recalcitrant BRVO following an injection of Avastin. Figure 2: OCT imaging showing resolution of macular edema related to BRVO following second injection of Avastin combined with MPLT treatment. Source (all): Sam Mansour, MD