Table of Contents
Ophthalmic artery (OA)
First branch of the internal carotid artery distal to the cavernous sinus.
see Considerations and limitations of anatomical studies delineating the relationship of the optic nerve and ophthalmic artery in the optic canal 1).
Segments
The ophthalmic artery is composed of three segments; intracranial, intracanalicular and orbital segments 2).
Branches of the OA supply all the structures in the orbit as well as some structures in the nose, face and meninges. Occlusion of the OA or its branches can produce sight-threatening conditions.
The ophthalmic artery has an anomalous origin in 2-3 % of cases and rarely arises from the anterior cerebral artery.
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Measurement of intracranial pressure (ICP) is necessary in many neurological and neurosurgical diseases. To avoid lumbar puncture or intracranial ICP probes, non-invasive ICP techniques are becoming popular. A recently developed technology uses Two Depth Transcranial Doppler to compare arterial pulsations in the intra- and extra-cranial segments of the ophthalmic artery for non-invasive estimation of ICP 3).
Case reports
During the anatomical dissection of an 81-year-old Caucasian male, the absence of the right ophthalmic artery in its usual location was evident from an endonasal transsphenoidal perspective. The specimen was then studied in detail, through multiple dissections, corrosion casting, high-resolution CT, and histological analysis. The English literature on anomalous origins of the ophthalmic artery was reviewed, together with reported associated pathologies. Anatomo-radiological analysis documented that the right ophthalmic artery arose from the inferior surface of A1 tract of the anterior cerebral artery (A1) and passed over the optic nerve in its subarachnoid tract. A meningo-ophthalmic artery was evident on the same side and reached the orbit through the superior orbital fissure. Histological examination of both internal carotid artery (ICA) walls documented a significantly decreased thickness of the tunica media and adventitia on the side of the anomalous ophthalmic artery, with a significantly different content of collagen types I and III. The literature review documented an association of aneurysms and anomalous ophthalmic arteries. To the best of our knowledge, this is the first anatomical report that includes a radiological and arterial wall analysis of a persistent ventral ophthalmic artery. The latter provides histological data that support the clinical evidence of a higher association of aneurysms with anomalous origins of the ophthalmic artery 4).
Computed tomography angiography
By 3D volume-rendering (VR) CTA. Bone subtraction was successful in all patients. The mean OA diameter was 1.37 ±0.25 mm in men, 1.35 ±0.16 mm in women (P = 0.188 for gender), 1.38 ±0.25 mm in the <40 years-old group, 1.37 ±0.14 mm in the 40-49 years-old group, 1.36 ±0.16 mm in the 50-59 years-old group, 1.38 ±0.19 mm in the 60-69 years-old group, and 1.34 ±0.17 mm in the > 70 years-old group (P = 0.662 for age group). CTA is a reliable method for visualizing the ophthalmic artery (OA). There are no major differences in OA diameter among gender or age 5).
Extremely rarely, the ophthalmic artery (OphA) arises from the A1 segment of the anterior cerebral artery (ACA). Discovery of this anomalous OphA during angiography or surgery has been reported in several patients.
Uchino et al. report a case in which an OphA of ACA origin was diagnosed by magnetic resonance (MR) angiography and confirmed by selective cerebral angiography. To our knowledge, this is the first report of this variation with MR angiography. Careful observation of MR angiographic images is important for detecting rare arterial variations. Partial maximum-intensity-projection images are useful in identifying tiny anomalous arteries on MR angiography 6).