Clinical Research Network Green or Yellow Laser for Diabetic Macular Edema Sponsored by the National Eye Institute National Institutes of Health US Department of Health and Human Services ID: 1044067
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1. The Diabetic Retinopathy Clinical Research NetworkGreen or Yellow Laser for Diabetic Macular EdemaSponsored by the National Eye Institute, National Institutes of Health, U.S. Department of Health and Human Services.1
2. BackgroundGreen (514-530 nm) and yellow (568-577nm) laser wavelengths are commonly used for macular photocoagulationTheoretical advantages of yellow over green laser have been suggestedData on effect of green vs yellow laser on DME clinical outcomes are limitedIn a retrospective observational study (N = 69, Browning 1999) and a randomized trial (N = 85, Karacorlu 1993), no significant differences in VA and macular thickening were reported between green and yellow laser wavelengths 2
3. Laser Wavelength Color 3Study Question: Is laser wavelength color (green or yellow) used for DME related to:Visual acuity outcomeOCT thickness outcomeNumber of laser treatments administered
4. MethodsAssess the distribution of consistent laser wavelength color used throughout the first and second year visits in 2 DRCR.net studies:Protocol I (LRT-DME): eyes assigned to sham + prompt laser, and ranibizumab + prompt laserProtocol B (IVT): eyes assigned to the laser groupRetrospective comparison of VA, OCT CSF, and number of treatment encounters, in non-randomized consistent green vs consistent yellow groups at 1 yr and 2 yr4
5. Distribution of Laser Wavelengths Used in Eyes that Completed 1 year Visit5LRT-DMEIVTSham + Laser (N=268)Ranibizumab + Prompt Laser (N=165)Laser (N=287)Always Green 66%72%68%Always Yellow21%21%25%Green/Yellow*12%7%7%* No specific order. Group not included in the analysis
6. Mean VALRT-DME Sham+Laser6P = 0.06*P = 0.13**Adjusted for baseline VA, age, HbA1c, DME treatment history, DR level, and lens status
7. 7Mean VALRT-DME Ranibizumab + Prompt LaserP = 0.86*P = 0.61**Adjusted for baseline VA, age, HbA1c, DME treatment history, DR level, and lens status
8. 8Mean VAIVT Laser*Adjusted for baseline VA, age, HbA1c, DME treatment history, DR level, and lens status
9. Visual AcuityLRT-DMEIVTShamRanibizumabLaserGreenYellowGreen YellowGreenYellowBaseline (N)178551193419571Mean ~Snellen6320/636520/5062 20/6366 20/5059 20/6359 20/631 Year (N)178551193419472Mean Change2.45.18.27.60.80.0P (baseline covariates-adjusted)*†0.060.860.702 Year (N)131431133218556Mean Change 2.46.06.57.51.52.6P (baseline covariates-adjusted)*†0.130.610.369* Data transformed due to skewness † Baseline VA, age, HbA1c, DME treatment history, DR level, and lens status
10. 10Mean OCT CSFLRT-DME Sham+LaserP = 0.39*P = 0.75**Adjusted for baseline CSF, age, HbA1c, DME treatment history, DR level, and lens status
11. 11Mean OCT CSFLRT-DME Ranibizumab + Prompt LaserP = 0.39*P = 0.**Adjusted for baseline CSF, age, HbA1c, DME treatment history, DR level, and lens status
12. 12Mean OCT CSFIVT LaserP = 0.52*P = 0.71**Adjusted for baseline CSF, age, HbA1c, DME treatment history, DR level, and lens status
13. OCT CSFLRT-DMEIVTShamRanibizumabLaserGreenYellowGreen YellowGreenYellowBaseline (N)178551193419471Mean4254274013804214181 Year (N)175551193418870Mean Change-108-93-137-117-106-89P (baseline covariates*-adjusted)0.390.390.542 Year (N)129421093217854Mean Change-135-139-147-116-143-133P (baseline covariates*-adjusted)0.750.210.7413* Baseline CSF, age, HbA1c, DME treatment history, DR level and lens status
14. Number of Laser TreatmentsLRT-DMEIVTShamRanibizumabLaserGreenYellowGreen YellowGreenYellowThrough 1 YearMean2.72.92.12.52.12.1P value*0.410.260.68Through 2 YearMean3.44.02.63.42.92.6P value*0.050.020.2714*Poisson Regression
15. Investigators 15LRT-DMEIVTShamRanibizumabLaserNumber of Investigators who Treated Eyes that Received Pure Green645089Number of Investigators who Treated Eyes that Received Pure Yellow241535Number of Investigators who Treated Eyes in Both Pure Green & Pure Yellow201
16. Summary: Wavelength UsageIn DRCR.net Protocol B (laser group) and protocol I, (sham + laser group and the ranibizumab + laser groups) through 1 year approximately 70% received only green color laser,20% received only yellow color laser, and 10% received both Within protocols B and I, there was little overlap in the roster of investigators that delivered only green or only yellow laser16
17. Summary: Number of Laser EncountersBy 2 years, eyes that received exclusively yellow laser in Protocol I (sham+laser and ranibizumab+laser arms) appear to have received more laser sessions than the eyes that received exclusively green.This was not observed in Protocol BProtocol B had fewer laser sessions overall relative to protocol I VA outcomes with laser in protocol B were not as positive as those in protocol I17
18. Limitations: Wavelength and Change in ThicknessImbalance in baseline factors may have influenced (confounded) the observed relation between VA and laser wavelength, and between CSF and laserAdjustments in the multi-variate models may not adequately address all potential confoundersEyes were not randomized to yellow or green laser, so other cofounding factors at baseline could account for differences detected in Protocol I18
19. There was a suggestion of a small to moderate difference on change in visual acuity by laser wavelength color was identified in the sham + laser cohort of Protocol I (2.4 Green, 5.4 Yellow) – although eyes not randomized so cannot rule out confounding factors contributing to the differenceDifference not confirmed in ranibizumab + laser group (effects of ranibizumab may overwhelm any differences that laser wavelength could have on vision).Difference not confirmed in Protocol B laser armFewer laser sessionsLess vision gain with laser19Summary: Wavelength and Change in Vision
20. There was a suggestion of some evidence in 1 cohort—not confirmed in 2 other cohorts— to suggest that laser wavelength has some impact on vision outcomes. The lack of confirmation in other cohorts makes it more likely that the finding is due to chance or factors, other than laser wavelength, which are confounding the results.Randomized trial to address role of laser wavelength not likely feasibleOnly 40% of eyes assigned to ranibizumab+deferred laser received laser by 2 yearsA large difference in outcomes not suggested by DRCR.net protocols, especially when macular laser is used with anti-VEGF treatment; determining if smaller differences truly exist would require a very large number of participants and may not be clinically relevant20Summary