Abstract
Purpose:
To measure unaffected retinal vessel diameter in eyes with macular edema (ME) secondary to branch retinal vein occlusion (BRVO) before and after intravitreal injection with bevacizumab (IVB).
Methods:
This was a retrospective, cohort study. Twenty-five consecutive patients with an eye with BRVO with ME that underwent IVB treatment in April 2012-April 2013 were participated. All subjects were assessed at baseline and 1, 3, and 6 months after IVB. Retinal vessel diameters in both eyes were measured by using a computer-assisted method. Fundus images were divided into four [superotemporal (ST), inferotemporal (IT), inferonasal (IN), and superonasal (SN)] quadrants. The diameters of the largest arteriole and venule in all quadrants except the occlusion-bearing quadrant were measured.<br />
Results:
At baseline, BRVO eyes had larger venular diameters in the ST, IT, IN, and SN quadrants than fellow eyes (P = 0.009, 0.016, 0.043, and 0.001, respectively). Twenty eyes did not develop recurrent ME after single IVB. In these eyes, the venular diameters in ST, IT, and IN were smaller than baseline venular diameter at 1 (P = 0.011, <0.001, and 0.039, respectively), 3 (P = 0.009, 0.001, and 0.007, respectively), and 6 (P = 0.014, 0.007, and 0.040, respectively) months after IVB. In the same 20 eyes, the arteriolar diameters in ST and IT quadrant decreased significantly only at 1 month after IVB (P = 0.048 and 0.010, respectively). Five patients (20%) had recurrent ME 3 months after IVB. At 1 month after IVB, the unaffected temporal venular diameters in the affected eye decreased by 12.23 ± 4.32 μm (P = 0.003 relative to baseline). At 3 months, these diameters increased by 11.86 ± 1.28 μm (P<0.001 relative to 1 month). These eyes underwent a second IVB injection. One and three months later, the venular diameters were significantly smaller than the diameters just before the second injection (P = 0.008 and 0.002, respectively).
Conclusions:
BRVO eyes had larger unaffected venular diameters than fellow eyes. ME resolution after IVB associated with vasoconstriction of unaffected retinal venules. ME recurrence associated with dilation of unaffected temporal venules. Changes in unaffected vessel diameter could indicate the pathological status of ME in BRVO eyes.