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The many symptoms and signs of lacrimal drainage disorders affect ocular function, ocular health and social interactions |
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The highly variable size of the tear lake is dependent upon a balance between tear production and clearance from the ocular
surface, the latter by evaporation or through the drainage pathways
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The lacrimal system can be considered as a three-compartment model: the tear lake being the first compartment, the lacrimal
sac the second, and the nasal space the third. Two zones of poor hydraulic conductance — the canaliculi and the nasolacrimal
duct — join the three compartments
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Signs and symptoms of lacrimal drainage disorders are either “flow-related” or “volume-related” |
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Flow-related characteristics are due to limitations of tear conductance from the lateral canthus to the nose — but especially
that due to the hydraulic resistance of the canaliculi and nasolacrimal duct. Cure of flow-related symptoms is not achievable
in every patient
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Being due to fluid within — or “backwash” from — the lacrimal sac, appropriate surgery will cure volume-related characteristics
in all cases
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Elimination of the second compartment (lacrimal sac) cures volume-related symptoms, this being achieved only with a large
osteotomy that permits a complete opening of the sac (from the fundus to nasolacrimal duct). Primary intention healing of
the mucosal union will maximise the anastomotic size and reduce fibrous contracture due to secondary intention healing — the
latter typically seen after endonasal or inadequate external surgery
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During external dacryocystorhinostomy, suturing of both the anterior and posterior mucosal flaps is readily achieved if an
anterior ethmoidectomy is routinely performed
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