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Effect of panretinal photocoagulation on choroidal circulation in the foveal region in patients with severe diabetic retinopathy

Aim: To study alterations in choroidal blood flow (CBF) in the foveal region after panretinal photocoagulation (PRP) in patients with severe proliferative diabetic retinopathy. Methods: Seventeen eyes of 17 patients with severe non-proliferative diabetic retinopathy (PDR) or with non-high-risk PDR and no macular oedema before PRP were included. All patients underwent four sessions of scatter PRP. We measured the choroidal blood velocity (CBVel), choroidal blood volume (CBVol) and CBF in the foveal region before and 1 month after PRP using a laser Doppler flowmetry. Results: Macular oedema did not develop after PRP in any treated eyes. One month after PRP, there was no significant change in the mean CBVel (311.2 (SD 61.2) Hz) compared with baseline (327.1 (74.1) Hz) (p = 0.17). In contrast, the mean CBVol and CBF values increased significantly by 51% (from 0.37 (0.12) arbitrary units (au) at baseline to 0.52 (0.16) au, p = 0.0025) and 46% (from 7.3 (2.4) au at baseline to 10.4 (4.4) au, p = 0.0014), respectively, 1 month after PRP. Conclusion: These results indicate that PRP may increase the CBF in the foveal region in eyes with severe diabetic retinopathy. The current results may be caused by vasodilation of the choriocapillaries in the foveal region.