STUDY SUBJECTS

Major Inclusion Criteria for Group 1, 2, X

Group I

• BRVO(3-18 months since onset)
• 5 disc diameters of retinal involvement
• Sufficient clearing of intraretinal hemorrhage to permit laser photocoagulation
• No diabetic retinopathy
• No other concurrent ocular disease affecting visual acuity

Group II

• BRVO(3-18 months since onset)
• NVD or NVE documented by FA or fundus photography
• Sufficient clearing of intraretinal hemorrhage to permit laser photocoagulation
• No diabetic retinopathy
• No other concurrent ocular disease affecting visual acuity

Group X (this group was NOT randomized)

• BRVO (3-18 months since onset)
• At least 5 disc diameters of capillary non perfusion
• No other concurrent ocular disease affecting visual acuity

RANDOMIZATION SCHEME AND INTERVENTIONS

Randomized 1:1

1. (a) Scatter argon laser photocoagulation
2. (b) No laser photocoagulation

Method of Scattered Laser: FA and fundus photography guided laser over area of involvement (200um-500 um spot size, 1 burn width apart) and no closer than 2 DD from the foveal center.

**Note: Early on in study, if Group II controls with neovascularization developed vitreous hemorrhage, they were treated as it was considered not ethical not to treat after vitreous hemorrhage appeared. Later on (after determining VH might not influence long term VA), laser treatment was withheld in the control group II if VH developed

Patients were followed q 4 months with visual acuity, ophthalmic examinations, and fundus photographs performed at each visits. FA was performed at initial and annual visits.

Study Duration: July 1st, 1977 to February 28th, 1984

PRIMARY ENDPOINT:

• Presence of neovascularization- observed on fundus examination and confirmed with fundus photography and FA
• Presence of vitreous hemorrhage— confirmed by examination and fundus photography

RESULTS

Study population

• Group 1: 319 eyes (154 with laser; 153 controls- of which 2 were treated with laser outside the protocol)
  • Mean Follow up: 3.7 years
• Group 2: 82 eyes (41 with laser; 41 controls)
  • Mean Follow up: 2.8 years

PRIMARY OUTCOME:

1) Presence of Neovascularization (NV) in Group I (BRVO of at least 5 DD)

• Group I: 22% in control group vs 12% in laser group
• Cox proportional hazard model: Statistically higher probability of developing neovascularization in the control group ( p = 0.02), if non perfusion was present (p= 0.0007), to in Group III (concurrent macular edema, p = 0.05).

2) Presence of Vitreous Hemorrhage (VH) in Group II (BRVO with existing NVD/NVE)

• Group II: 61% in control group versus 29% in laser group
• Cox proportional hazard model: Statistically lower risk of developing VH if treated with laser (p = 0.003) and high risk in those eyes with shorter duration of occlusion (p = 0.03).

NOTABLE SECONDARY OUTCOMES

• NV development in Group 1: 31% of nonperfused control eyes (defined as at least 5 DD of non perfusion on FA) developed NV in Group 1 versus 19% of Group 1 non perfused laser treated eyes; 63% of the 19% treated eyes developed a VH
• Bottom Line Author Inferences from above:
  • 12% of nonperfused eyes treated BEFORE the development of NV can be expected to get a VH
  • 9% of nonperfused eyes treated AFTER the development of NV can be expected to get a VH
• Group X: 41% of eyes with more than 5 DD of non perfusion developed NV
• 9% rate of fellow eye developing a BRVO or CRVO

Adverse events

• 1 patient developed pre-retinal fibrosis with traction that resolved two years later

CONCLUSION

• Laser photocoagulation reduces rate of NV and VH in BRVO patients
• Patients with > 5 DD of non perfusion should be followed at q4 month intervals for NV
• Laser photocoagulation is recommended in BRVO patients after the development of NV