Abstract
Purpose: :
While both bevacizumab and triamcinolone have been shown to reduce macular edema in patients with both diabetic retinopathy and retinal vein occlusion, relatively little is known about the kinetics of the response. This study was performed to characterize short term changes in macular thickness and volume in the first hours and days following a single intravitreal injection of one or both of these agents.
Methods: :
IRB approval was obtained for this prospective study. Nine patients with macular edema secondary to diabetes or retinal vein occlusion consented to enrollment, undergoing treatment with intravitreal triamcinolone and/or bevacizumab. Seven patients were treated with intravitreal triamcinolone 4.0 mg including five with diabetic macular edema. Of the four patients with retinal vein occlusion, two received triamcinolone, one bevacizumab 1.25 mg, and one both agents simultaneously. Optical coherence tomography scans were taken at baseline, 1, 3, 6, 24, 48 hours, and 1 week post injection using both the spectral domain Cirrus and the time domain Stratus machines (Carl Zeiss Meditec, Inc., Dublin, CA).
Results: :
Cirrus measurements of central macular thickness (CMT) were significantly reduced at 3 hours (P = 0.03, paired t-test) and volume at 6 hours (P = 0.03) with continued decline thereafter. Measurements by the Stratus also showed a decline, but only after 24 hours for both CMT (P = 0.03) and volume (P = 0.04). CMT measurements were 40.9 um (28.6 - 53.2 um) thicker on the Cirrus compared to the Stratus while volume measurements were 3.47 um3 (3.27-3.66 um3) higher with the Cirrus. Rates of decline were calculated using data from the Cirrus. For responders, they were 0.02-0.3 um/min and 0.001-0.004 um3/min for CMT and volume respectively.
Conclusions: :
Significant CMT and volume reductions occur in the first 6 hours after injection and at a rate that may be related to the pump function of the retinal pigment epithelium. There did not appear to be any appreciable differences in kinetics between triamcinolone and bevacizumab nor between the two disease categories but the sample sizes were small and the study not powered to detect such a difference.
Keywords: macula/fovea • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • diabetic retinopathy