Abstract
Purpose: :
To study the eight-year progression in the baseline diameter and the diameter response of retinal arterioles to increased blood pressure in patients with type 2 diabetes mellitus and mild retinopathy.
Methods: :
Forty-four Type 2 diabetic patients with mild diabetic retinopathy who in 2003 underwent a routine eye examination including a measurement of the diameter response of retinal arterioles, were re-examined in 2011. The age at follow-up was 64.7 ± 0.8 years (mean±SEM) and the known diabetes duration was 17.2 ± 1.0 years (mean±SEM). The diameter of retinal arterioles at baseline and during increased blood pressure induced by isometric exercise were studied using a Dynamic Vessel Analyzer (DVA, Imedos). The changes in retinal blood flow induced by the increase in the blood pressure were estimated by calculating the gain factor, and changes over time were compared using a paired t-test.
Results: :
During the follow-up period retinopathy decreased in 18 patients, was unchanged in 12 patients, and increased in 14 patients, but none of the patients developed diabetic maculopathy or proliferative diabetic retinopathy during the follow-up period. The baseline diameter of retinal arterioles showed a significant decrease from 118.8 ± 2.1 microns to 113.5 ± 2.0 microns (mean±SEM), p=0.003, but no significant change in the gain factor which was 0.08± 0.23 and -0.06 ± 0.07 (mean±SEM), p=0.55 at the initial and the follow-up examination, respectively. There were no significant changes in HbA1c or blood pressure during the follow-up period.
Conclusions: :
Patients with type 2 diabetes mellitus experience a decrease in the diameter of retinal arterioles, but unchanged diameter response to an increase in the arterial blood pressure, during the early period of the disease where retinopathy is mild. A possible influence of the diameter response of retinal arterioles on the development of diabetic retinopathy occurs in retinopathy stages with more severe retinopathy.
Keywords: diabetic retinopathy