Abstract
Purpose: :
To assess long-term changes in flow parameters of the retrobulbar vessels in diabetic patients.
Methods: :
This was a historical prospective study of 138 eyes that were evaluated in our institution between 1994-1995, 36 were re-evaluated between 2004-2008 and formed the study group. They were divided into four groups for comparison: eyes of diabetic patients without diabetic retinopathy (DR), eyes with nonproliferative DR (NPDR), eyes with PDR and eyes of non-diabetic patients (controls). Color Doppler imaging was used to access the retrobulbar circulation. Flow velocity in the three major retro-bulbar vessels was measured, and the resistive index (RI) was calculated and compared between the groups and between the two time periods.
Results: :
There was a similar increase in the RI of the ophthalmic artery (OA) in all patient groups. RI values of the central retinal artery (CRA) and posterior ciliary artery (PCA) had increased in the two non-DR groups and in the NPDR group, with a surprising decrease measured in eyes with PDR (P=NS). Combining the NPDR and PDR groups resulted in a milder increase of the RI of the PCA and the CRA in the DR group compared to the other groups..
Conclusions: :
We showed that there was a decrease of the resistance in two retrobulbar vessels in patients with PDR during a long-term follow-up. The finding of a milder increase of the RI in patients with DR compared to the non-DR controls was, significant for the CRA. These results demonstrate that an increase of the resistance in the retrobulbar vessels, as a part of DR, can lessen over time and even be reversed. These results are unexpected given the direct statistical relationship between the duration of the diabetes and the severity of the retinopathy that was reported in several studies. They are, however, in line with the results of follow-up studies that were carried out using laser Doppler velocimetry. Further studies are needed in order to verify these findings and their contribution to better understanding of the pathophysiology of DR.
Keywords: imaging/image analysis: clinical • blood supply • diabetic retinopathy