Autoregulation of retinal arterioles in diabetics and normal subjects

Background: Measurement of myogenic autoregulation of retinal arterioles wa s demonstrated by the use of the Retinal-Vessel-Analyzer (Carl Zeiss, Jena) . The purpose of the presented study was to find a significant difference o f this myogenic response in a group of healthy individuals vs, a group of p atients with pathologic conditions. Patients and methods: As a group of patients with known pathology in microc irculation patients with type 1 diabetes were choosen. By isometric exercis e an identical rise in mean arterial blood-pressure was provoked in 20 pati ents with type-1 diabetes and 20 matched healthy volunteers. The myogenic r esponse of retinal arterioles was measured in both groups by the use of the Retina l-Vessel-Analyzer. The Wilcoxon test was used for statistical analy sis within the two groups whereas both groups were compared with each other by the use of the Mann-Whitney test. Results: Having the same age and same blood-pressure rise (p = 0.624) a sig nificant better myogenic response was found in the healthy subjects vs. the diabetic group (p = 0.008). In the diabetec group no correlation was found between myogenic response and duration of diabetes (p = 0.982) or HbA1c va lues (P = 0.83). Conclusions: In this study significant loss of autoregulation in patients w ith type 1 diabetes is demonstrated. By the use of the Retinal-Vessel-Analy zer noninvasive testing of the function of autoregulation of retinal arteri oles is possible. This method might prove to be of great value in early det ection of diabetic vessel pathology.