STUDY SUBJECTS

Major inclusion criteria:

• Central Retinal Vein Occlusion (CVO) as noted on fundus photographs (4 quadrants of retinal hemorrhages and venous dilation)
• CVO of at least 3 months’ duration
• Macular edema involving fovea as determined by the Reading Center on FA
• VA of 20/50 to 5/200 (as measured by ETDRS)
• No improvement in VA on 2 consecutive visits prior to entry
• Phakic
• IOP of < 30 mm Hg

Major exclusion criteria:

• Previous treatment with laser photocoagulation
• Concurrent ocular disease that may affect VA over study period
• Presence of diabetic retinopathy (either eye), vitreous hemorrhage, retinal neovascularization or other retinal vascular diseases in study eye
• Peripheral anterior synechiae
• Inability to discontinue heparain/warfarin for duration of study
• Aphakia, pseudophakia or significant lens opacity
• Macular non perfusion noted on FA

Randomization scheme and interventions:

Randomized 1:1

1. (a) Grid macular argon laser photocoagulation
2. (b) No laser photocoagulation
3. Method of Grid Laser: The settings were the following: spot size 100 microns, moderate intensity, 0.1 second duration, 0.5-1 burn width apart. FA guided laser over area of capillary leakage within 2 disc diameters of the foveal center was performed; laser could not extend beyond 2 disc diameters from fovea or within foveal avascular zone.
4. Fluorescein angiograms were obtained at baseline, 4 month visit, and annually for 3 years. Fundus photographs were taken at each visit and 48 hours after treatment. If VA improvement was 9 letters or less and treatable macular edema was still present on angiography, then the patient was retreated.


5. Study Duration: 3 years or until end of the study

PRIMARY ENDPOINT:

• Visual Acuity (VA)— as measured by ETDRS

RESULTS

Study population

• 155 patients (77 grid laser and 78 controls-no treatment)

PRIMARY OUTCOME:

• No significant differences in mean VA or change in VA between grid laser and observation at any follow up visit (baseline, 4 months, each annual visit up to 3 years).

NOTABLE SECONDARY OUTCOMES

• 23 of 77 patients (30%) required a retreatment
• No difference in VA outcomes in patients with < 1 year versus > 1 year duration of CRVO
• There was a statically reduction in macular edema in the treated versus untreated eyes (31% versus 0% with complete resolution).
• There was an age interaction based on treatment: VA deteriorated in patients > 60 years that were treated and VA tended to improve in younger patients that were treated. However, this interaction went away after controlling for other potential interactions.

Adverse events

• None reported

CONCLUSION

• Grid argon laser photocoagulation does not improve visual acuity outcomes in CVO patients with macular edema and a VA of 20/50 or worse compared to observation