Anatomic and Radiographic Analysis of the Optic Canal and Orbital Apex

Abstract OBJECTIVE: To define the microsurgical anatomy of the central retinal artery (CRA) and to provide a guide to avoiding damage to it during surgery. METHODS: The anatomic characteristics of the CRA and small arteries distributed to the optic sheath were examined in 109 orbits. The origin, course, and site of entry of the artery into the optic sheath and the distance between the orbital apex and the site of entry into the sheath were examined. RESULTS: The CRAs originated directly from the intraorbital ophthalmic artery or in a common trunk with a posterior ciliary or a muscular branch. The CRAs most commonly originated on the inferomedial side of the ophthalmic artery an average of 8.4 mm distal to the orbital end of the optic canal. They penetrated the optic sheath near the junction of the middle and anterior thirds of the length of the intraorbital optic nerve an average of 18.6 mm distal to the optic canal. More than 70% of CRAs penetrated near the midline of the lower surface of the optic sheath, 21% entered the inferomedial surface, and 7% the inferolateral or lateral surface of the optic sheath. Only one CRA gave off a branch before penetrating the nerve. CONCLUSION: The CRA is at risk of being damaged or occluded during procedures involving a large part of the orbit. Procedures directed along the lower half of the proximal two-thirds of the optic sheath have the greatest risk of interrupting the artery.

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Endoscopic transnasal image-guided approach to diagnosis in orbital apex and optic canal lesions

The Journal of Laryngology & Otology ◽

10.1017/s0022215119000975 ◽

2019 ◽

Vol 133 (06) ◽

pp. 501-507 ◽

Cited By ~ 1

Author(s):

S N Unadkat ◽

C E Rennie ◽

W E Grant

Keyword(s):

Skull Base ◽

Optic Canal ◽

Cerebrospinal Fluid Leakage ◽

Orbital Apex ◽

Malignant Tumours ◽

Immunoglobulin G4 ◽

Presenting Symptoms ◽

Hunt Syndrome ◽

Impact On Treatment ◽

Benign Tumours

AbstractObjectivePrompted by a recurring skull base multidisciplinary team debate on the necessity of securing a definitive tissue diagnosis before initiating treatment for lesions of the orbital apex, a review of anterior skull base procedures over an 11-year period was undertaken.MethodsData collected prospectively on cases from 2006 to 2017 were analysed. Presenting symptoms, imaging and histology findings, outcomes, complications, and impact on treatment were evaluated. All surgery was carried out endoscopically with the aid of image guidance.ResultsTwenty-one patients undergoing endoscopic orbital apex and/or optic canal biopsy were included. The mean patient age was 49 years. Five malignant tumours were identified, five benign tumours, seven infective cases (two tuberculosis and five fungal) and two cases of immunoglobulin G4 related disease. Two patients had non-diagnostic biopsies (one lesional) and were treated successfully as Tolosa–Hunt syndrome cases.ConclusionA successful diagnosis was achieved in nearly all cases without adverse impact, other than one cerebrospinal fluid leakage case. Management was directly influenced by the outcome in all cases.

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