Purpose: This study was designed to examine the characteristics of retrobulbar circulation and the role of glycemic control in patients with diabetes and varying stages of retinopathy.
Methods: Seventy-three eyes in 37 patients with diabetes were assigned to one of the following four study groups: nonproliferative diabetic retinopathy (non-PDR), proliferative diabetic retinopathy (PDR), post-panretinal photocoagulation (PRP), or preretinopathy (the control group). Color Doppler imaging was used to quantitate peak systolic blood flow velocities of the central retinal artery (CRA), the central retinal vein (CRV), the posterior ciliary artery (PCA) and the ophthalmic artery. Glycated hemoglobin (HbA1c) levels were used as an indicator of glycemic control.
Results: The authors found that the CRA maximum blood flow velocity levels were significantly higher in the pre-retinopathy group (9.8 +/- 2.1 cm/second) than in the non-PDR group (8.1 +/- 2.2 cm/second). In addition, the CRV maximum blood flow velocity levels were significantly higher in the pre-retinopathy group (5.7 +/- 0.9 cm/second) than in both the PDR group (4.8 +/- 1.5 cm/second) and the PRP group (4.9 +/- 1.7 cm/second). No significant differences were seen in blood flow velocity levels of the ophthalmic artery and the PCA among the retinopathy groups. No correlation was found between HbA1c levels and the stage of retinopathy. The presence of systemic hypertension showed no significant effect on blood flow velocities in the various retinopathy groups.
Conclusion: This study demonstrates the presence of some circulatory changes in the CRA and the CRV in patients' eyes with diabetic retinopathy when compared with patients' eyes in the pre-retinopathy stage of the disease. These data support the contention that changes in retrobulbar circulation and microcirculation occur during the pathogenesis of diabetic retinopathy. The clinical significance of these findings needs to be determined.