Changes in Choroidal Blood Flow in Response to the Treatment of Diabetic Macular Edema

Abstract

Purpose: : Evaluate changes to retinal thickness and choroidal blood flow in the foveal avascular zone in response to focal laser or intravitreal triamcinolone treatment for clinically significant diabetic macula edema.

Methods: : A retrospective series of four patients who were treated for diabetic macular edema with focal laser or intravitreal triamcinalone were evaluated pre– and post–treatment with an average follow–up interval of 6.5 weeks. The outcome measures were visual acuity, central retinal thickness quantified by ocular coherence tomography, and fovealor choroidal blood flow assessed by laser doppler flowmetry, the measurement of the shift in frequency of incident light scattered by moving red blood cells according to the Doppler effect.

Results: : The pre–treatment visual acuity remained stable or improved at the post–treatment follow–up 6.5 weeks later (visual acuity range count–finger to 20/20). The average central retinal thickness decreased 14.7%. The choroidal blood flow in the foveal avascular zone decreased 53.5% while the choroidal blood volume decreased 46.8% in the treated eye compared to the untreated eye which was used as the control in this study.

Conclusions: : The choroidal blood flow and volume in the foveal avascular zone decreased post–treatment in our cohort of patients correlated with decreased central retinal thickness. Although one might expect increased volume and flow in the choroidal circulation as the retinal thickness decreases with less physical impedance to the laser doppler flowmetry, we postulate that the decreased choroidal blood flow and volume may reflect improved retinal oxygenation post–treatment in the foveal avascular zone.

Keywords: diabetic retinopathy • laser