title: Effect of isometric exercise on choroidal blood flow in type I diabetic patients.
abstract: 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.
  
  
  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.
authors.affiliation: Laboratoire de d'Optique et de Biophysique, Institut de Recherche en Ophtalmologie, Grand Champsec 64, CP 4168, 1950 Sion 4, Switzerland.
authors.forename: Armand
authors.initials: A
authors.lastname: Movaffaghy
authors.forename: Stéphane R
authors.initials: SR
authors.lastname: Chamot
authors.forename: André
authors.initials: A
authors.lastname: Dosso
authors.forename: Constantin J
authors.initials: CJ
authors.lastname: Pournaras
authors.forename: Jorg R
authors.initials: JR
authors.lastname: Sommerhalder
authors.forename: Charles E
authors.initials: CE
authors.lastname: Riva
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D002829:Choroid / Q000098:blood supply*; D003922:Diabetes Mellitus, Type 1 / Q000175:diagnosis* / Q000503:physiopathology; D003930:Diabetic Retinopathy / Q000175:diagnosis* / Q000503:physiopathology; D015444:Exercise / Q000502:physiology*; D005260:Female; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D012016:Reference Values; D012025:Reflex, Pupillary / Q000502:physiology