Diagnostic imaging of the nasolacrimal drainage system. Part I. Radiological anatomy of lacrimal pathways. Physiology of tear secretion and tear outflow

Abstract

Excessive watering of the eye is a common condition in ophthalmological practice. It may be the result of excessive production of tear fluid or obstruction and insufficiency of efferent tear pathways. The differentiation between obstruction and insufficiency of the lacrimal pathways is still clinically questionable. In the diagnostic process it is necessary to perform clinical tests and additional diagnostic imaging is often needed. Dacryocystography, with or without the extension of the dynamic phase or subtraction option, still remains the criterion standard for diagnostic imaging of the lacrimal obstruction. It may help to clarify the cause and exact place of the obstruction and provide information for further management, especially surgical treatment. Increasingly, new techniques are used in diagnostic imaging of the lacrimal tract, such as computed tomography, magnetic resonance, and isotopic methods. Adequate knowledge of the anatomy and physiology of the lacrimal system and the secretion and outflow of tears is the basis for proper diagnostic imaging. The purpose of this paper is to present the exact anatomy of the lacrimal system, with particular emphasis on the radiological anatomy and the current state of knowledge about the physiology of tear secretion and drainage.

Figure 1

Le Fort fracture, type II scheme. Based on RosarioVanTulpe scheme.

Figure 2

Le Fort fracture, type II. CT volume reconstruction.

Figure 3

Lacrimal system shapes and sizes. With kind permission of Jane Olver, Color Atlas of Lacrimal Surgery, Oxford, 2002.

Figure 4

Anatomical types connecting the upper and lower canaliculi to the lacrimal sac. Based on Yazici B, Yazici Z. Frequency of the common canaliculus. A radiological study. Arch Ophthalmol, 2000; 118: 1381–85.

Figure 5

Mucocele formation diagram. With kind permission of Jane Olver, Color Atlas of Lacrimal Surgery, Oxford, 2002.

Figure 6

(A) Dorsal view of the lacrimal system of a right eye (male, 68 years) removed from its bony canal. (B) Corrosion vascular cast of a right orbit. Arrows mark the ophthalmic artery with a branch (arrowheads) to the lacrimal fossa (lf). (C) Scanning electron microscopic photograph of a horizontally sectioned lacrimal system. Wide-lumened blood vessels (arrows) surround the lumen of the lacrimal passage (arrowheads). (D) Medial view of the lower part of the lacrimal system of a right eye (female, 72 years) removed from its bony canal. ulc, upper lacrimal canaliculus; llc lower lacrimal canaliculus; ls, lacrimal sac; nd, nasolacrimal duct; m, mucous membrane of the nose; hv, Hasner’s valve, opening of the nasolacrimal duct into the inferior meatus of the nose. Magnification: (A) 32; (B) 31; (C) 37.5; (D). With permission of prof. F.P. Paulsen and Association for Research in Vision and Ophthalmology. Paulsen FP, Thale AB, Hallmann UJ et al: The Cavernous Body of the Human Efferent Tear Ducts: Function in Tear Outflow Mechanism, IOVS, 2000; 41(5)

Figure 7

Valves arrangement diagram of nasolacrimal drainage system. Based on Warwick R. Anatomy of the Eye and Orbit, 7^th ed. Philadelphia: WB Saunders, 1976; 232.