Comparison of Modified ETDRS and Mild Macular Grid Laser Photocoagulation
Strategies for Diabetic Macular Edema
Sponsored by the National Eye Institute, National Institutes of Health, U.S. Department of Health and Human Services
ObjectiveObjective Compare two laser photocoagulation techniques:
Modified ETDRS focal photocoagulation (mETDRS) to areas of edema
• Direct treatment to microaneurysms• Grid to diffuse leakage
Mild macular grid (MMG) laser technique • small mild burns throughout macula• in areas with and without edema• no direct treatment of microaneurysms
BackgroundBackground Presumed mechanism of focal photocoagulation
include Closure of microaneurysms Reduced blood flow leading to auto-regulation and reduced
edema Improved oxygenation leading to auto-regulation and reduced
edema Stimulation of biochemical processes in RPE
Would light widespread laser (mild macular grid, MMG) to the macula be effective?
Pilot clinical trial
44
Study DesignStudy Design
mETDRS N=162 Eyes MMG N=161
Randomized Clinical Trial (Pilot Study)
Major Eligibility Criteria Assessed:Major Eligibility Criteria Assessed:>18 years old
Type 1 or type 2 diabetes
Study eye meets the following criteria (subjects allowed 2 study eyes): Best corrected electronic ETDRS visual acuity score of ≥19Definite retinal thickening on clinical exam due to previously untreated DMERetinal thickness measured on OCT of 250 μm or more in the central subfield or 300 μm or more in at least 1 of the 4 inner subfieldsHad no prior laser or other treatment for DME.
• Subjects with 2 study eyes: 1 eye was randomly assigned to receive 1 treatment and 1 eye was assigned to receive the other.
Mild Macular GridMild Macular Grid
40 minutes post laser treatment
6 weeks post laser treatment
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.
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Follow-up and Treatment ScheduleFollow-up and Treatment Schedule
3.5 Month± 2 Weeks
12 Month± 4 Weeks
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.
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8 Month± 4 Weeks
Primary outcome: Change in OCT
Secondary Outcome: Change in visual acuity
(Method: Repeated measures least squares regression models)
Measurements by certified Evaluator• Best-corrected electronic ETDRS visual
acuity• OCT-measured retinal thickness
Macular laser photocoagulation was repeated if DME persisted and such treatment was warranted in the opinion of the investigator, according to the treatment guidelines.
Baseline Demographics and Clinical Characteristics
Baseline Demographics and Clinical Characteristics
Subject Characteristics mETDRS Group(N=162 eyes)
MMG Group (N=161 eyes)
Gender: Women - N(%) 38% 43%
Age (yrs) - Mean+SD 58+11 59+11
Race - N(%)
White 63% 64%
African-American 18% 19%
Hispanic or Latino 10% 8%
Asian 5% 4%
Other 4% 4%
Baseline Demographics and Clinical Characteristics
Baseline Demographics and Clinical Characteristics
mETDRS Group
(N=162 eyes)
MMG Group (N=161 eyes)
Diabetes Type - N(%)
Type 1 7% 6%
Type 2 93% 94%
Duration of Diabetes (years) - Mean+SD
14+9 13+8
HbA1c (%) - Mean+SD 8.2+1.9 8.2+2.1
Baseline Demographics and Clinical Characteristics Cont.
Baseline Demographics and Clinical Characteristics Cont.
Ocular Characteristics mETDRS Group
(N=162 eyes)
MMGGroup
(N=161 eyes)
E-ETDRS Visual Acuity (letter score) - N(%)
> 84: 20/20 or better 27% 20%
83-69: < 20/20 to 20/40 47% 57%
68-49: < 20/40 to 20/100 22% 17%
48-34: < 20/100 to 20/200 4% 4%
33-19: < 20/200-20/400 0% 2%
Mean+SD - letters 74+12 73+14
OCT mETDRS Group
(N=162 eyes)
MMGGroup
(N=161 eyes)
Central Subfield Thickness (microns) Mean+SD
335+128 346+118
Maximum retinal thickening of central and innersubfields (microns, see text) Mean+SD
148+122 163+111
Number of eyes with at least 1 unthickened subfield - N(%)
60% 55%
Baseline Demographics and Clinical Characteristics Cont.
Baseline Demographics and Clinical Characteristics Cont.
Mean Central Subfield ThicknessMean Central Subfield Thickness
Percent Edema Resolved for Central Subfield Thickness
P=0.29
P=0.23
P=0.56
Percent of Edema Resolved for Weighted Inner Zone ThicknessPercent of Edema Resolved for Weighted Inner Zone Thickness
Note: Weighted inner zone thickness is a weighted average of the thickness in the central and 4 inner subfields
P=0.57
P=0.02
P=0.07
Percent of Edema Resolved for Maximum Retinal Thickening
Percent of Edema Resolved for Maximum Retinal Thickening
Note: Maximum thickening is the maximum amount of excess thickness of the central and 4 inner subfields
P=0.57
P=0.26 P=0.93
Percent of Edema Resolved for Retinal Volume
Percent of Edema Resolved for Retinal Volume
Note: Retinal volume is a weighted average of the thickness in the central, 4 inner and 4 outer subfields converted to mm3
P=0.31
P=0.01 P=0.12
Percent with ≥ 10 Letter Improvement in Visual Acuity
Percent with ≥ 10 Letter Improvement in Visual Acuity
Percent with ≥ 10 Letter Worsening in Visual Acuity
Percent with ≥ 10 Letter Worsening in Visual Acuity
SummarySummary
Maximum retinal thickening in the inner zone (within 1500 microns of macular center), central subfield thickness, weighted inner zone thickness and retinal volume decreased in both groups
MMG less effective than mETDRS in reducing retinal thickening
Visual acuity similar in both groups