Background: In healthy subjects, choroidal blood flow is regulated when the mean ocular perfusion pressure increases. Since capillary vascular beds are altered in diabetic patients, the regulation of choroidal blood flow could be affected by this pathology.
Patients and methods: 10 type I diabetic patients without retinopathy (DNR group) and 7 type I diabetic patients with retinopathy (DR group) participated in the study. In NDR and DR groups, choroidal blood flow was measured while patients raised their mean arterial blood pressure by squatting. The results were compared to those of a previous study in normals. Pupillometry was performed at rest on the two diabetic groups and on seven normals during a modification of illumination (white/black screen transition).
Results: In the NDR and DR groups, mean ocular perfusion pressure raised by 61 and 50 % during squatting, respectively. Consecutively, choroidal blood flow did not change in NDR as in normals, but increased linearly in DR patients. The white/black screen transition produced an increase of the pupil diameter of 52 and 49 % in normals and NDR patients, respectively, while it increased by only 16 % in the DR patients.
Conclusions: As already shown in healthy subjects, choroidal blood flow is regulated in NDR patients when the ocular perfusion pressure increases. In DR patients, the absence of this control could be due to a failure of the autonomic nervous system, as suggested by pupillometry results.