First Author: T.Komoto JAPAN
Co Author(s): Y. Minowa M. Hamada K. Inagaki K. Ohkoshi
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Recently anti-VEGF therapy has been established as main treatment strategy for diabetic macular edema (DME) treatment. However some patients with persistent macular edema or non-responder require laser treatment. Micropulse laser is less invasive procedure to reduce enlargement of laser scar to adjacent tissue. We have been used micropulse laser for closure of microaneurysm (MA) adjacent to foveola with minimal energy. OCT-A (optical coherence tomography angiography) is non-invasive instrument to visualize vascular structure including MA in patients with DME. Purpose of this study is to evaluate the efficacy of OCT-A to confirm the MA closure immediately after micropulse laser therapy.
This is retrospective observation study. From August 7, 2015 to March 28, 2016, 26 eyes of 24 patients with DME underwent OCT-A guided threshold laser photocoagulation using micropulse laser to coagulate microaneurysm responsible for foveal cystoid macular edema at St Luke’s International Hospital.
All patients were followed up until 3 months after the surgery. Micropulse laser (IQ577® IRIDEX Corporation) was applied directly to the leaking MA with least energy to visualize change in colour of MA. OCT-A (RTVue XR Avanti; Optovue Inc., Fremont, CA, USA and Cirrus HD-OCT 5000 OCT-Angiography; Carl Zeiss Meditec, Jena, Germany) was done before, one hour, 1 month, and 3 months after surgery to visualize the vascular signal to evaluate the closure of MA. Change in CMT, BCVA (logMAR), and vascular signal in OCT-A at laser ablation sites were evaluated before, one hour, 1 month, and 3 months after surgery. We evaluated the image of MAs of 21 eyes 19 patients whose OCT-A images was visualized with sufficient quality for analysis. Among those eyes, 88 MA were evaluated (mean:4.19 MA per eye). We defined as closure of MA when OCT-A vascular signal at laser site changed to be absent in whole retinal layer after laser ablation.
Among 88 MA treated with micropulse laser, MA closure was detected 10 / 40(25%) at one hour, 41/ 85(48%) at 1 month, 43 /69(62%) at 3 month after surgery. Two patients showed re canalization of MA in 3 month. In two patients, MA did not closed at one hour, but changed to be closed later at 1 or 3 month. BCVA at before and 1 month and 3 month after surgery was 0.21, 0.20, 0.18, and was improved significantly after surgery (p <0.02 Wilcoxon’s signed-rank test). Mean CMT before, 1,3 months after surgery was 383.1μm, 377.7μm 343.5μm, and significantly decreased at 3months (p < 0.04, Wilcoxon’s signed-rank test). Cystoid spaces at foveal area disappeared in 3/21 eyes (14%) and decreased in 7/21 eyes (33%) at 3 months. No patient complained scotoma until 3 months after laser ablation.
OCT-A is useful for confirming MA closure immediately after threshold energy laser treatment. OCT-A guided laser photocoagulation for MA closure may contribute to reduce the energy of MA closure, especially in patients with leaking MA close to the foveal centre. Micropuse threshold photocoagulation for persistent CME may contribute to reduce macular edema and improve visual acuity in patients with DME.