Abstract
Purpose: :
To evaluate the extent of peripheral retinal non-perfusion in patients with branch or central retinal vein occlusion (BRVO & CRVO) and to determine the effect of the area of ischemia on the response to treatment, and requirement for re-treatment.
Methods: :
Patients presenting with BRVO or CRVO at the Medical Center Ophthalmology Associates, San Antonio, Texas, were treated with intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF) and/or dexamethasone intravitreal implant (Ozurdex). At all visits, patients underwent 200-degree widefield fluorescein angiography (FA) and color fundus photography using the Optos 200Tx, and spectral domain optical coherence tomography (OCT) using the Cirrus OCT. The FA images were centered on the fovea, then steered peripherally. All images were graded by a masked investigator. The areas of ischemia were mapped out using a validated software (GRADOR), and this was calculated as a percentage of the total area of retina visible.
Results: :
The mean age of the 21 patients was 74.6 years. The mean area of retinal ischemia was 13.8% (range, 0% to 51.4%, SD ± 16.5), with 12 patients (57.1%) having ischemia of ≤10%, while the remaining 9 (42.9%) had areas of ischemia >10%. The area of non-perfusion was larger when macular edema was present compared to when the edema had resolved (15.0% vs. 9.8%, p<0.001). With macular edema, the mean central subfield thickness on OCT showed a trend to be thicker in those with total areas of ischemia >10% compared to those ≤10% (535.3 µm vs. 425.1 µm, p=0.107). Similarly, the decrease in OCT thickness in response to treatment was greater for those with ischemia >10% (295.7 µm vs. 166.8 µm, p=0.053). Patients with >10% ischemia had worse visual acuity (VA) with macular edema present (62.8 letters vs. 70.3) and experienced a larger gain in VA with treatment (11.1 letters vs. 4.3). The time to recurrence of macular edema was slightly longer for those with areas of ischemia >10% (3.1 vs. 2.8 months). There was no difference in the number of anti-VEGF or Ozurdex treatments given between the 2 groups.
Conclusions: :
Patients with BRVO and CRVO demonstrate considerable variability in the extent of peripheral retinal non-perfusion at baseline, which appears to affect the initial amount of retinal thickening and the magnitude of reduction in retinal thickness on OCT and improvement in VA with treatment. Increased areas of peripheral retinal non-perfusion may drive VEGF production and result in more severe macular edema.
Keywords: retina • imaging/image analysis: clinical • ischemia