STUDY SUBJECTS

Group 1: Eyes at risk for development of neovascularization (NV)

• BRVO with an onset of 3-18 months from enrollment and at least 5 disc diameters of involvement
• Eyes were randomized to “scatter” laser photocoagulation versus no laser

Group 2: Eyes at risk for vitreous hemorrhage

• BRVO (3-18 months within onset) and presence of retinal neovascularization
• Randomization to scatter laser versus no laser

Group X: Eyes at “high” risk for neovascularization

• BRVO (3-18 months within onset) and 5 disc diameters of capillary non perfusion
• Observed

Group 3: Eyes at risk for vision loss from macular edema

• BRVO (3-18 months since onset)
• Macular edema reducing visual acuity (VA) to 20/40 or worse
• Randomization: “grid” pattern laser in macula versus no laser

Major Inclusion Criteria for Group 3 (Macular Edema)

• BRVO (3-18 months since onset)
• VA of 20/40 or worse- as measured by special front-lighted diabetic retinopathy study charts with Snellen or Sloan letters
• FA evidence of macular edema involving fovea
• Sufficient clearing of intraretinal hemorrhage to permit FA evaluation and laser
• Absence of foveal hemorrhage
• No other concurrent ocular disease affecting visual acuity

Major exclusion criteria:

• Patients using anticoagulants for systemic conditions that could not be discontinued

RANDOMIZATION SCHEME AND INTERVENTIONS

Randomized 1:1

1. (a) Grid macular argon laser photocoagulation
2. (b) No laser photocoagulation

Method of Grid Laser: FA guided laser over area of capillary leakage in the macula, no closer to the fovea than the edge of the foveal avascular zone, and not extending peripherally to the major vascular arcade

Patients with laser were evaluated 4 months later with an FA. If persistent leakage and foveal edema was present with continued decreased visual acuity, then repeat focal grid laser was performed. Patient follow ups were done q 4 months with visual acuity (VA), stereoscopic fundus photographs at each visit and FA a initial follow up and annual visits.

Study Duration: July 1st, 1977 to February 28th 1984. Average duration of follow up was 3.1 years

PRIMARY ENDPOINT:

• VA gain of 2 or more lines for at least 2 consecutive visits—evaluated at year 3.

RESULTS

Study population

• 139 eyes (68 control; 71 laser treated)

PRIMARY OUTCOME:

• 2 or more lines of VA gain from baseline: 65% laser group versus 27% control group
• Treated eyes gained a mean of 1.33 lines of VA in laser versus 0.23 lines in control group
• Multivariate model of a 2 line or more vision gain : statistically higher probability of vision gain if in treated group, those with lowest duration of occlusion, and those not taking HTN medications
• 2 or more lines of VA loss from baseline: 12% laser group versus 17% control group (no difference p=0.43044)

NOTABLE SECONDARY OUTCOMES

• Eyes of patients on HTN meds had less vision gains in the control groups (15% with 2 or more lines in vision gain versus 50% of nonhypertensive patient eyes)
• Per authors, there was a weak trend indicating that laser may be associated with better vision gains in those taking HTN medications than those that did not take HTN medications. However, it was not statistically significant (p = 0.25).
• High chance of vision gain in the first year after the occlusion occurred (70% vision gain vs 32% after 1 year) and held true whether in the control group or treatment group. However, there was no difference in treatment effect whether intervention occurred before or after one year of BRVO onset.

Adverse events

• None reported

CONCLUSION

• Grid argon laser photocoagulation improves visual acuity outcomes in patients with BRVOs and a VA of 20/40 or worse from macular edema (in the absence of foveal hemorrhage or ischemia)