Abstract
Purpose: :
To test the effect of locally applicated tropicamide (M4 muscarinic acetylcholine receptor blocker) on the retinal blood flow and on the diameter of the retinal blood vessels.
Methods: :
We measured retinal blood flow (RBF) and the vessel diameter of retinal arteries and veins (RAD, RVD). 25 healthy subjects (healthy group), 24 patients with low tension glaucoma (LTG), and 14 patients with primary open angle glaucoma (POAG) were examined before and 30 minutes after local application of one drop of 0.5% tropicamide into the right eye. The mean age of the healthy group, LTG–group and POAG–group was 53 ± 13, 58±12, and 55±13 years, respectively. The collateral left eye was used as control eye. RBF, RAD and RVD was examined by Heidelberg Retina Flowmetry SLDF. The statistical analysis was performed by the Man–Whitney–Wilcoxon–test.
Results: :
30 minutes after local application of one drop of 0.5% tropicamide into the right eye the retinal perfusion decreased significantly by 33 ± 15% (p<0.0001) in the healthy group, by 39± 18% (p<0.0001) in the LTG–group, and by 42±16% (p<0.0001) in the POAG–group. The retinal blood flow of the control eyes did not change significantly. The diameter of retinal veins RVD decreased significantly by 6.3% (p=0.008) in the healthy group, and by 5,6% (p=0.05) in the POAG–group. In LTG we found no significant RAD and RVD changes.
Conclusions: :
Locally applicated tropicamide was associated with a reduction of the retinal blood flow and of the venous vessel diameter. This observation suggests a vasoconstriction of the retinal vasculature.
Keywords: retina • blood supply • acetylcholine