The Diabetic Retinopathy Clinical Research Network Green or Yellow Laser for Diabetic Macular Edema Sponsored by the National Eye Institute, National Institutes of Health, U.S. Department of Health and Human Services. 1

Background  Green ( nm) and yellow ( nm) laser wavelengths are commonly used for macular photocoagulation  Theoretical advantages of yellow over green laser have been suggested  Data on effect of green vs yellow laser on DME clinical outcomes are limited  In 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

Laser Wavelength Color 3  Study Question: Is laser wavelength color (green or yellow) used for DME related to: Visual acuity outcome OCT thickness outcome Number of laser treatments administered

Methods  Assess 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 laser Protocol B (IVT): eyes assigned to the laser group  Retrospective comparison of VA, OCT CSF, and number of treatment encounters, in non- randomized consistent green vs consistent yellow groups at 1 yr and 2 yr 4

Distribution of Laser Wavelengths Used in Eyes that Completed 1 year Visit 5 LRT-DMEIVT Sham + Laser (N=268) Ranibizumab + Prompt Laser (N=165) Laser (N=287) Always Green 67%72%68% Always Yellow21% 25% Green/Yellow*12%7% * No specific order. Group not included in the analysis

Mean VA LRT-DME Sham+Laser 6 P = 0.06*P = 0.13* *Adjusted for baseline VA, age, HbA1c, DME treatment history, DR level, and lens status

7 Mean VA LRT-DME Ranibizumab + Prompt Laser P = 0.85* P = 0.68* *Adjusted for baseline VA, age, HbA1c, DME treatment history, DR level, and lens status

8 Mean VA IVT Laser *Adjusted for baseline VA, age, HbA1c, DME treatment history, DR level, and lens status

Visual Acuity LRT-DMEIVT ShamRanibizumabLaser GreenYellowGreenYellowGreenYellow Baseline (N) Mean ~Snellen 63 20/ / / / /63 1 Year (N) Mean Change P (baseline covariates- adjusted) * † Year (N) Mean Change P (baseline covariates- adjusted) * † * Data transformed due to skewness † Baseline VA, age, HbA1c, DME treatment history, DR level, and lens status

10 Mean OCT CSF LRT-DME Sham+Laser P = 0.39*P = 0.82* *Adjusted for baseline CSF, age, HbA1c, DME treatment history, DR level, and lens status

11 Mean OCT CSF LRT-DME Ranibizumab + Prompt Laser P = 0.39*P = 0.17* *Adjusted for baseline CSF, age, HbA1c, DME treatment history, DR level, and lens status

12 Mean OCT CSF IVT Laser P = 0.54*P = 0.74* *Adjusted for baseline CSF, age, HbA1c, DME treatment history, DR level, and lens status

OCT CSF LRT-DMEIVT ShamRanibizumabLaser GreenYellowGreenYellowGreenYellow Baseline (N) Mean Year (N) Mean Change P (baseline covariates * - adjusted) Year (N) Mean Change P (baseline covariates * - adjusted) * Baseline CSF, age, HbA1c, DME treatment history, DR level and lens status

Number of Laser Treatments LRT-DMEIVT ShamRanibizumabLaser GreenYellowGreenYellowGreenYellow Through 1 Year Mean P value* Through 2 Year Mean P value * *Poisson Regression

Investigators 15 LRT-DMEIVT ShamRanibizumabLaser Number of Investigators who Treated Eyes that Received Pure Green Number of Investigators who Treated Eyes that Received Pure Yellow Number of Investigators who Treated Eyes in Both Pure Green & Pure Yellow 201

Summary: Wavelength Usage  In 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 laser 16

Summary: Number of Laser Encounters  By 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. oThis was not observed in Protocol B oProtocol B had fewer laser sessions overall relative to protocol I o VA outcomes with laser in protocol B were not as positive as those in protocol I 17

Limitations: Wavelength and Change in Thickness  Imbalance in baseline factors may have influenced (confounded) the observed relation between VA and laser wavelength, and between CSF and laser Adjustments in the multi-variate models may not adequately address all potential confounders  Eyes were not randomized to yellow or green laser, so other cofounding factors at baseline could account for differences detected in Protocol I 18

 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 difference  Difference 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 arm Fewer laser sessions Less vision gain with laser 19 Summary: Wavelength and Change in Vision

 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 feasible Only 40% of eyes assigned to ranibizumab+deferred laser received laser by 2 years A 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 relevant 20 Summary