An%20Observational%20Study%20of%20the%20Development%20of%20Diabetic%20Macular%20Edema%20Following%20Panretinal%20(Scatter)%20Photocoagulation%20(PRP)%20Given%20in%201%20or%204%20Sittings - PowerPoint PPT Presentation

Title: An%20Observational%20Study%20of%20the%20Development%20of%20Diabetic%20Macular%20Edema%20Following%20Panretinal%20(Scatter)%20Photocoagulation%20(PRP)%20Given%20in%201%20or%204%20Sittings


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• An Observational Study of the Development of
  Diabetic Macular Edema Following Panretinal
  (Scatter) Photocoagulation (PRP) Given in 1 or 4
  Sittings
• Sponsored by the National Eye Institute,
• National Institutes of Health, U.S. Department of
  Health and Human Services.

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Background Panretinal Photocoagulation (PRP)
for PDR

• PRP is the standard treatment of PDR
• Usually performed over 1 or more sittings
• (ETDRS 2 or more sittings)
• 2004 survey of DRCR.net investigators
  one-quarter routinely use one sitting for PRP

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PRP and Macular Edema

• PRP associated complications include macular
  edema
• ETDRS - 18 developed macular edema 4 months
  after full PRP (1200 1600 spots)
• Theories
• Oncotic fluid accumulation related to tissue
  destruction
• PRP induced inflammation leading to cytokine
  release and increased permeability of the retinal
  capillaries

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What are Some Pros and Cons of Delivering PRP in
1 Sitting?

• Pros
• Convenience
• Completion before complications occur e.g.,
  vitreous hemorrhage (VH)
• Cons (theoretical)
• May cause macular edema with VA loss
• Greater patient discomfort
• Need for retrobulbar or peribulbar anesthetic
• Higher risk of acute pressure rise, angle
  closure, or choroidal effusion

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What are Some Pros and Cons of Delivering PRP in
More Than One Sitting?

• Pros (theoretical)
• Allows edema and associated VA loss to subside
  before next PRP sitting
• Cons
• Inconvenient
• Potential for failure to complete intended
  treatment plan (VH)

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Primary Study Objective

• Determine the incidence of new macular edema on
  OCT, following PRP in diabetic eyes without
  center edema at 34 weeks
• To compare the incidence of macular edema with a
  1-sitting versus 4-sitting regimen

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Non-Randomized Study Rational

• Investigators who complete PRP in one sitting
  were unwilling to perform PRP in multiple
  sittings and vice versa
• Therefore, prospective nonrandomized study
  conducted

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Study Design
Prospective, Non-Randomized Study

• Major Eligibility Criteria Assessed
• gt18 years old
• Type 1 or type 2 diabetes
• Early-PDR or Severe-NPDR (high risk PDR not
  eligible)
• Retinal thickness on OCT lt 300 microns in the
  central subfield
• Visual Acuity letter score gt 73 (20/32 or better)
• No clinical DME requiring treatment

Investigator declared, prior to study initiation,
if PRP planned for 1 or 4 sittings for all
subjects participating in protocol
1 Sitting
4 Sittings
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PRP Treatment Regiment

• 1200-1600 total burns (ETDRS parameters)
• Retrobulbar/peribulbar anesthesia optional
• Slit lamp delivery systems

1 Sitting and 4 Sitting

• Each session 4 weeks apart (4 days)
• 300 burns in each of first two sittings
• Investigator discretion for of burns in 3rd and
  4th sittings
• Total of 4 sittings between 1200 and 1600 burns

4 Sittings
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PRP Burn Characteristics

• Laser Parameters

Burn Size 200 microns with Rodenstock lens (or equivalent) 500 microns with three mirror contact lens
Burn Duration 0.05 0.2 seconds (0.1 recommended)
Wavelength Green to yellow (red if vitreous hemorrhage present)
Intensity Standard mild white burns
Distribution Edges at least 1 burn width apart, no closer than one row within the arcades and two disc diameters temporal to the fovea
Extent Arcades to at least the equator
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Outcome Assessment

• Visual acuity measured at 3 meters with the
  Electronic-ETDRS Visual Acuity (EVA) device
• Central Subfield Thickness Using Zeiss Stratus OCT

3 Day 4 Week 17 Week

• Central Subfield Thickness
• Primary Outcome
• E-ETDRS Visual Acuity
• 3-Field Fundus Photographs

34 Week
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Results
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Study Enrollment
155 subjects enrolled at 27 sites
1 sitting 84 subjects
4 sittings 71 subjects
34-week Visit Completion (Primary Outcome)
1 sitting 88
4 sittings 82
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Baseline Characteristics

• Women 48 44
• Median Age 56 yrs 54 yrs
• Race
• White 64 46
• African-American 24 28
• Hispanic or Latino 11 18
• Asian 0 6
• More than one race 1 1

4 Sitting
1 Sitting
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Baseline Characteristics
4 Sitting
1 Sitting

• Diabetes Type
• Type 1 19 25
• Type 2 81 75
• Median Duration of Diab. 18 yrs 20 yrs
• Median HbA1c () 7.7 8.2

HbA1c Missing 7 in one-sitting group, 13 in 4
sitting group
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Baseline Characteristics
4 Sitting
1 Sitting
Prior Focal Macular Laser 14 11 Median E-ETDRS
Letter Score 85 83 (Snellen equivalent) 20/20 20/2
0 Median OCT CSF Thickness 207µ 198µ CSF 250
299 Microns 3 (4) 1 (1) Median OCT Retinal
Volume 6.9 mm3 7.0 mm3
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Baseline Retinopathy Severity
4 Sitting
1 Sitting
N 81 66 Mild NPDR 6 0 Moderate NPDR
9 3 Moderately Severe NPDR 30 38 Severe
NPDR 6 8 Mild PDR 23 15 Moderate
PDR 14 15 High Risk PDR 11 18 Cannot
Grade 1 3
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Scatter Treatment
4 Sitting
1 Sitting
N 84 71
4 Sitting
Median of Burns Median Average
Power Retrobulbar Injection Incomplete
Treatment Additional PRP
1 Sitting
1274 280mW 46 0 7
1260 250mW 14 15 0
Total over all 4 sittings. At least once
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Central Subfield Thickness

• 1-sitting 4-sitting P value
• Baseline 207µ 198µ

• Change from baseline - median microns
• 3d 9 5 0.01
• 4wks 13 5 0.003
• 17wks 14 15 0.08
• 34wks 14 22 0.06

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Central Subfield Retinal Thickness 34 Weeks vs.
Baseline
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CSF 250 Microns and Change from Baseline 25
Microns
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Macular Edema on Fundus Photos at 34 weeks
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Treatment of DME

• One eye in each group was treated for DME prior
  to 34 weeks

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E-ETDRS Visual Acuity
1 Sitting 4 Sitting P Value

• Baseline 85 83
• Change from baseline
• 3d -3 -1 0.005
• 4wks -1 -1 0.37
• 17wks -1 -1 0.66
• 34wks 0 -2 0.006

Mean Letter Score
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E-ETDRS Visual Acuity 3 Day
N82
N66
2
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E-ETDRS Visual Acuity 4 Week
N78
N67
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E-ETDRS Visual Acuity 17 Week
N77
N63
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E-ETDRS Visual Acuity 34 Week
N72
N56
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2
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Vitreous Hemorrhage

• A vitreous hemorrhage reducing visual acuity by
  10 or more letters occurred in 2 eyes in each
  group.

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Discussion
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Summary

• Treatment groups balanced on baseline factors
• Number of total burns similar between treatment
  groups
• Retrobulbar anesthesia more commonly used in
  1-sitting group

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Summary

• CSF Thickness Remained Normal in Most Eyes
• 3 Days
• CSF Greater in 1 than 4 Sitting Group
• 34 Weeks
• CSF Greater in 4 than 1 Sitting Group
• Differences Unlikely to be Clinically Relevant
• VA and OCT Results Consistent

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Conclusion

• Eyes Without Edema
• Single Sitting PRP
• Safe
• Little Change in VA or Edema
• 1 Sitting vs. 4 Sitting PRP
• Clinically Meaningful Differences Unlikely
• VA and OCT Changes Similar

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Study Limitations

• 1 Sitting vs. 4 Sitting PRP
• Small Sample Size
• Only Large Differences Ruled Out
• Non Randomized Study Design
• Uncontrolled Confounding Possible

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Conclusion

• 1 Sitting vs. 4 Sitting PRP
• Results Apply Only to Eyes Without Edema
• Impact if 1 4 Sittings Clinically Equivalent
• One Sitting Benefits and Risks
• Increased Patient Convenience
• Decreased Patient Cost Travel Productivity
• Possible Risk of Retrobulbar Anesthesia
• Unknown if results apply to eyes with DME

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Thank You

• Subjects who volunteered to participate in this
  trial
• 27 clinical study sites investigators,
  coordinators, and
• other staff
• DRCR Network Data and Safety Monitoring
  Committee
• DRCR Network General Steering Committee
• Other DRCR Network investigators and staff
• Sponsor National Eye Institute of the National
• Institutes of Health (U.S. Department of
  Health and
• Human Services
• For further information and all DRCR Network
  financial disclosures,
• go to www.drcr.net

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