title: Sub-threshold micro-pulse diode laser treatment in diabetic macular edema: A Meta-analysis of randomized controlled trials.
abstract: OBJECTIVE
  To examine possible differences in clinical outcomes between sub-threshold micro-pulse diode laser photocoagulation (SDM) and traditional modified Early Treatment Diabetic Retinopathy Study (mETDRS) treatment protocol in diabetic macular edema (DME).
  
  
  METHODS
  A comprehensive literature search using the Cochrane Collaboration methodology to identify RCTs comparing SDM with mETDRS for DME. The participants were type I or type II diabetes mellitus with clinically significant macular edema treated by SDM from previously reported randomized controlled trials (RCTs). The primary outcome measures were the changes in the best corrected visual acuity (BCVA) and the central macular thickness (CMT) as measured by optical coherence tomography (OCT). The secondary outcomes were the contrast sensitivity and the damages of the retina.
  
  
  RESULTS
  Seven studies were identified and analyzed for comparing SDM (215 eyes) with mETDRS (210 eyes) for DME. There were no statistical differences in the BCVA after treatment between the SDM and mETDRS based on the follow-up: 3mo (MD, -0.02; 95% CI, -0.12 to 0.09; P=0.77), 6mo (MD, -0.02; 95% CI, -0.12 to 0.09; P=0.75), 12mo (MD, -0.05; 95% CI, -0.17 to 0.07; P=0.40). Likewise, there were no statistical differences in the CMT after treatment between the SDM and mETDRS in 3mo (MD, -9.92; 95% CI, -28.69 to 8.85; P=0.30), 6mo (MD, -11.37; 95% CI, -29.65 to 6.91; P=0.22), 12mo (MD, 8.44; 95% CI, -29.89 to 46.77; P=0.67). Three RCTs suggested that SDM laser results in good preservation of contrast sensitivity as mETDRS, in two different follow-up evaluations: 3mo (MD, 0.05; 95% CI, 0 to 0.09; P=0.04) and 6mo (MD, 0.02; 95% CI, -0.10 to 0.14; P=0.78). Two RCTs showed that the SDM laser treatment did less retinal damage than that mETDRS did (OR, 0.05; 95% CI, 0.02 to 0.13; P<0.01).
  
  
  CONCLUSIONS
  SDM laser photocoagulation shows an equally good effect on visual acuity, contrast sensitivity, and reduction of DME as compared to conventional mETDRS protocol with less retinal damage.
authors: Southern Medical University, Guangzhou 510515, Guangdong Province, China; Department of Ophthalmology, Guangdong General Hospital Affiliated to Southern Medical University, Guangzhou 510515, Guangdong Province, China; Mianyang Central Hospital, Mianyang 621000, Sichuan Province, China.
authors: Gang
authors: G
authors: Qiao
authors: Department of Ophthalmology, Guangdong General Hospital Affiliated to Southern Medical University, Guangzhou 510515, Guangdong Province, China.
authors: Hai-Ke
authors: HK
authors: Guo
authors: Mianyang Central Hospital, Mianyang 621000, Sichuan Province, China.
authors: Yan
authors: Y
authors: Dai
authors: Mianyang Central Hospital, Mianyang 621000, Sichuan Province, China.
authors: Xiao-Li
authors: XL
authors: Wang
authors: Department of Ophthalmology, Guangdong General Hospital Affiliated to Southern Medical University, Guangzhou 510515, Guangdong Province, China.
authors: Qian-Li
authors: QL
authors: Meng
authors: Southern Medical University, Guangzhou 510515, Guangdong Province, China.
authors: Hui
authors: H
authors: Li
authors: Southern Medical University, Guangzhou 510515, Guangdong Province, China.
authors: Xiang-Hui
authors: XH
authors: Chen
authors: Southern Medical University, Guangzhou 510515, Guangdong Province, China.
authors: Zhong-Lun
authors: ZL
authors: Chen
keywords: diabetic macular edema; laser photocoagulation; sub-threshold