Alteration of choroidal circulation in the foveal region in patients with type 2 diabetes

Aim: To investigate changes in choroidal blood flow (CBF) in the foveal region in patients with type 2 diabetes. Methods: Laser Doppler flowmetry was used to determine the CBF in the foveal region in 70 patients with type 2 diabetes and 36 age and sex matched healthy subjects ( control group). The patients were classified into three groups: 33 patients ( 33 eyes) with no diabetic retinopathy (NDR), 20 patients ( 20 eyes) with non-proliferative diabetic retinopathy and no macular oedema (NPDR/MO-), and 17 patients ( 17 eyes) with NPDR and MO (NPDR/MO+). Optical coherence tomography was also used to measure the foveal thickness. Results: The group averaged CBF values were 13.5 (4.9), 9.4 (2.5), 10.8 (4.8), and 5.6 (2.0) ( arbitrary units) in the control, NDR, NPDR/MO-, and NPDR/MO+ groups, respectively. The group averaged CBF values in the NDR group decreased (30.2%; p< 0.01) compared with the control group. The average CBF value in the NPDR/MO+ group was also significantly lower (48.2%; p< 0.01) compared with that in the NPDR/MO- group. Conclusion: The CBF in the foveal region significantly decreases in patients with diabetes, especially those with macular oedema.