Applied anatomy of endoscopic transnasal lacrimal duct reconstruction by grafting of autogenous tissue

Hai TAO; Zhizhong MA; Haiyang WU; Shike HOU; Peng WANG; Wei WANG; Cui HAN

ABSTRACT

BACKGROUND:

Endoscopic transnasal lacrimal duct reconstruction by grafting of autogenous tissue is a novel method for treatment of severe lacrimal duct obstruction and it needs detailed anatomical data for surgery.

OBJECTIVE:

To study the applied microsurgical anatomy of lacrimal duct and to provide anatomical evidence for endoscopic transnasal lacrimal duct reconstruction by grafting of autoganous tissue.DESIGN, TIME AND

SETTING:

This study was performed at the laboratory of the Department of Ophthalmology, Armed Police General Hospital from July 2006 to June 2007.MATERIALS Twenty 10% formaldehyde-treated adult cadaveric heads, 14 males and 6 females, comprising 40 lacrimal ducts were included in this study.

METHODS:

The cadaveric heads were split on the level of the line between the superior border of the superciliary arch and the site 10 mm higher than occipital tuberosity. After removal of brain tissue,the heads were decalcified for approximate 1 week with 10%nitric acid. This promised non-alteration of morphological structure and facilitation for surgical cutting. Following dissection of facial cranium in the median sagittal plane, the nasal septum was excised to expose the lateral wall of the nasal cavity.MAIN OUTCOME

MEASURES:

The anteroposterior diameter and depth of lacrimal fossa; at middle third level, the thickness of lacrimal fossa at the anterior lacrimal crest, vertical middle line, and posterior lacrimal crest; the cross section area of nasolacrimal canal upper opening, middle part, and lower opening; horizontal distance, 30° oblique distance, and 45°oblique distance from lacrimal caruncie to nasal cavity; distance from lacrimal caruncle to nasolacrimal canal upper opening; and the included angle between lacrimal caruncle-nasolacrimal canal upper opening line and Aeby's plane.

RESULTS:

The length, anteroposterior diameter, and depth of lacrimal fossa were (17.85±1.72) mm, (6.74+1.28) mm, and (3.09+0.78) mm, respectively. At middle third level, the thickness of lacrimal fossa at the anterior lacrimal crest,perpendicular bisector, and posterior lacrimal crest was (4.03±0.89) mm, (0.61±0.36) mm, and (0.63±0.24) mm, respectively.Anterior lacrimal crest was significantly thicker than vertical middle line and posterior lacrimal crest (P ＞ 0.05). Horizontal distance, 30°oblique distance, and 45° oblique distance from lacrimal caruncle to nasal cavity was (17.23±0.70) mm,(14.51±1.72) mm, and (17.34±2.38) mm, accordingly, with a difference which was not significant (P ＞ 0.05). The distance from lacrimal caruncle to lateral wall middle point of nasolacrimal duct superior opening was (11.86±1.84) mm, and the included angle between lacrimal caruncle-lateral wall middle point of nasolacrimal duct superior opening line and Aeby's plane averaged (49.9±1.8)°.

CONCLUSION:

The distances from lacrimal caruncle to nasal cavity and lacrimal sac and the included angles between lacrimal caruncle-nasolacrimal canal upper opening line and Aeby's plane provide guidance significance for selection of bony opening position on the lateral wall of nasal cavity and determinations of tunnel oblique angle and autogenous tissue length. Creation of bony tunnel should start from the middle or posterior middle part of lacrimal fossa and then extend towards anterior inferior region with an optimal downward oblique angle of 45°. The length of autogenous tissue used for lacrimal duct reconstruction should exceed 21.22 mm.