An update on the variations of the orbital blood supply and hemodynamic.
OBJECTIVE
Several variations of the arterial blood supply of the orbit have been reported over the years. This review is aimed to provide an update focusing on three important issues: (a) variations of the ophthalmic artery origin; (b) contribution of the external carotid artery to the orbital blood supply; (c) orbital hemodynamic.


METHODS
A PubMed and Google search was carried out with the following keywords: ophthalmic artery origin, ophthalmic artery anastomoses and ophthalmic artery anatomy.


RESULTS
The site of origin of the ophthalmic artery displays a limited number of variations. However they are important as they are also associated with course variations. Anastomoses between the ophthalmic artery and the external carotid artery are numerous and many of them can acquire clinical relevance. Records on their anatomic frequency are limited. Orbital hemodynamic variations are a poorly studied subject. Recent investigations in children have unveiled unexpected variability and instability in the way the blood flows through the orbit.


CONCLUSIONS
The orbit shows several possible arterial variations. Some of them have a profound influence on its hemodynamic at least in children. More studies are required to ascertain if the hemodynamic variability observed in children can be pinpointed also in adults.
Department of Molecular and Developmental Medicine, University of Siena, Via Aldo Moro 2, 53100, Siena, Italy. eugenio.bertelli@unisi.it.
Eugenio
http://orcid.org/0000-0002-9681-4556
E
Bertelli
Department of Molecular and Developmental Medicine, University of Siena, Via Aldo Moro 2, 53100, Siena, Italy.
Marì
M
Regoli
Unit of Neuroimaging and Neurointervention (NINT), Department of Neurological and Sensorineural Sciences, Azienda Ospedaliera Universitaria Senese, Policlinico "Santa Maria alle Scotte", Siena, Italy.
Sandra
S
Bracco
D002342:Carotid Artery, External / Q000033:anatomy & histology*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D009880:Ophthalmic Artery / Q000033:anatomy & histology*; D009915:Orbit / Q000098:blood supply*; D012039:Regional Blood Flow / Q000502:physiology
Anastomosis; Hemodynamic; Ophthalmic artery; Orbit; Visibility index