Vol 78, No 1 (2019)
Original article
Published online: 2018-07-17

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Morphometric characteristics of the optic canal and the optic nerve

M. Radunovic1, B. Vukcevic1, N. Radojevic2, N. Vukcevic1, N. Popovic1, A. Vuksanovic-Bozaric1
Pubmed: 30106467
Folia Morphol 2019;78(1):39-46.

Abstract

Background: The optic nerve (ON), a major component of the visual system, is divided into four segments: the intrabulbar (IB), the intraorbital (IO), the intraca- nalicular (ICn) and the intracranial (ICr). The ICr ends with the two nerves partially decussating in the optic chiasm (OCh). The purpose of this study is to provide a detailed description of the dimensions of the OC (the diameter and the surface area of its foramina and the central segment, as well as the length of the OC and the thickness of its walls) as well as the ON (the length of the ON segments, the diameter of the ICn segment of the ON, the angle of decussation in the OCh, as well as the distance between the two ON at the cranial foramen of the OC). 

Materials and methods: The acquired data was then used to estimate the volu- me of the OC and the ICn segment of the ON. The morphometric research was performed on 25 cadavers (17 male and 8 female) and 30 skulls. 

Results: The surface area of the central segment of the OC was significantly smaller than the cranial foramen (p = 0.02) and the orbital foramen (p = 0.009). The inferior wall of the OC was significantly shorter than the other OC walls (p < 0.0001). The IO segment of the ON was the longest, where the difference to the ICn and ICr was statistically significant (p < 0.0001). The surface area of the ON at the cranial foramen was significantly larger than the surface area at the central segment of the OC (p = 0.02) and orbital foramen (p < 0.0001). The difference between the surface areas of the ON at the orbital foramen and the central segment of the OC was also statistically significant (p = 0.01). The estimated volume of the OC was calculated to be 190.72 mm3, and the volume of the ICn segment of the ON was estimated to be 50.25 mm3. 

Conclusions: It is absolutely crucial to open the central segment of the OC when decompressing the ON, due to the narrowing of the OC in this segment. 

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References

  1. Akdemir G, Tekdemir I, Altin L. Transethmoidal approach to the optic canal: surgical and radiological microanatomy. Surg Neurol. 2004; 62(3): 268–74; discussion 274.
  2. Berge JK, Bergman RA. Variations in size and in symmetry of foramina of the human skull. Clin Anat. 2001; 14(6): 406–413.
  3. Berlis A, Putz R, Schumacher M. Direct and CT measurements of canals and foramina of the skull base. Br J Radiol. 1992; 65(776): 653–661.
  4. Bourjat P, Bittighoffer B. [Radio-anatomical variants of the optic canal]. J Radiol. 1984; 65(10): 711–712.
  5. Chou PI, Sadun AA, Lee H. Vasculature and morphometry of the optic canal and intracanalicular optic nerve. J Neuroophthalmol. 1995; 15(3): 186–190.
  6. Choudhry R, Anand M, Choudhry S, et al. Morphologic and imaging studies of duplicate optic canals in dry adult human skulls. Surg Radiol Anat. 1999; 21(3): 201–205.
  7. Cook MW, Levin LA, Joseph MP, et al. Traumatic optic neuropathy. A meta-analysis. Arch Otolaryngol Head Neck Surg. 1996; 122(4): 389–392.
  8. Duke-Elder. System of Ophthalmology, Vol II. The anatomy of the visual system. Henry Kimpton, London 1961: 283–286.
  9. Govsa F, Erturk M, Kayalioglu G, et al. Neuro-arterial relations in the region of the optic canal. Surg Radiol Anat. 1999; 21(5): 329–335.
  10. Hart CK, Theodosopoulos PV, Zimmer LA. Anatomy of the optic canal: a computed tomography study of endoscopic nerve decompression. Ann Otol Rhinol Laryngol. 2009; 118(12): 839–844.
  11. Ji Y, Qian Z, Dong Y, et al. Quantitative morphometry of the orbit in Chinese adults based on a three-dimensional reconstruction method. J Anat. 2010; 217(5): 501–506.
  12. Kalthur S, Periyasamy R, Kumar S, et al. A morphometric evaluation of the optic canal: Comparative study between computerized tomographic study and direct anatomic study. SJMMS. 2015; 3(3): 204.
  13. Karakaş P, Bozkir MG, Oguz O. Morphometric measurements from various reference points in the orbit of male Caucasians. Surg Radiol Anat. 2002; 24(6): 358–362.
  14. Kier EL. Embryology of the normal optic canal and its anomalies. An anatomic and roentgenographic study. Invest Radiol. 1966; 1(5): 346–362.
  15. Lang J. Clinical anatomy of the posterior fossa and its foramina. Georg Thieme Verlag, Stuttgart – New York 1991: 82–85.
  16. Lang J, Gehmann G. Formenentwicklung des canalis opticus, seine masse und einstellung zu den schadelebenen. Verh Anat Ges. 1976; 70: 567–574.
  17. Mağden A, Kaynak S. Bilateral duplication of the optic canals. Ann Anat. 1996; 178(1): 61–64.
  18. Maniscalco J, Habal M. Microanatomy of the optic canal. J Neurosurg. 1978: 402–406.
  19. O’Rahilly R, Muller F. Human embryology & teratology. Wiley – Liss, New 2001: 395–414.
  20. Oztürk A, Bozbuğa M, Bayraktar B, et al. Surgical anatomy and morphometric analysis of the optico-chiasmatic apparatus, optic canal and sphenoid ridge. Okajimas Folia Anat Jpn. 1999; 75(6): 319–322.
  21. Peyman G, Sanders D, Goldberg M. Principles and practice of ophthalmology. W.B. Saunders Co, Philadelphia - Tokyo 1980: 3–87.
  22. Radunović M, Vitosević Z, Cetković M, et al. Morphometric analysis of the fascicular organisation of the optic nerve. Vojnosanit Pregl. 2015; 72(2): 132–135.
  23. Renn W, Rhoton A. Microsurgical anatomy of the sellar region. J Neurosurg. 1975: 288–298.
  24. Slavin KV, Dujovny M, Soeira G, et al. Optic canal: microanatomic study. Skull Base Surg. 1994; 4(3): 136–144.
  25. Wohlrab TM, Maas S, de Carpentier JP. Surgical decompression in traumatic optic neuropathy. Acta Ophthalmol Scand. 2002; 80(3): 287–293.