Atlas of the external diseases of the eye : including a brief treatise on the pathology and treatment / by O. Haab ; edited by G. E. de Schweinitz.

  • Haab, O. (Otto), 1850-1931.
Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: Atlas of the external diseases of the eye : including a brief treatise on the pathology and treatment / by O. Haab ; edited by G. E. de Schweinitz. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    traumatism. If the lower lid is torn at the inner canthus by a blow with the fist or a stick, the lower canaliculus is usually divided. In rare cases epiphora is due to the presence of a concretion, usually a mass of fungus, in the lower canaliculus; but in the great majority of cases the primary cause is a stricture in the lachrymonasal duct, which forms the communication between the lachrymal sac and the inferior meatus of the nose. The lachrymal sac, to the nasal side of the inner canthus, lies partially embedded in a groove of the lachrymal bone (fossa sacci lacrimalis), which is bridged over in front by the internal palpebral ligament. This structure can be brought plainly into view as a* tense, horizontal band by drawing the eyelid outward, toward the temple. The lachrymonasal duct is lodged within a bony canal, the narrowest portion of which corresponds to the opening of the lachrymal sac into the duct; this point is therefore the most frequent seat of stricture. Stricture or occlusion also occurs in the lower extremity of the canal, being caused by swelling of the mucous membrane either of the nose (usually temporary) or of the duct itself.* In order to understand the occurrence of obstructions in the drain- age-system, which are particularly common in the early stages of the disease and are often only temporary, it must be remembered that the lachrymonasal duct (like the inferior meatus of the nose) contains a venous plexus re- sembling cellular tissue, which from its great liability to congestion is very apt to produce a temporary occlusion. This also explains the excessive flow of tears in coryza. Unlike the lachrymal sac, the nasal duct is surrounded by bone and cannot expand when the secretion accumulates in excess, so that swelling of its vascular lining rapidly pro- duces a stenosis which may eventually become permanent. For these reasons catarrh of the lachrymonasal duct usually forms the first stage of a long and tedious process which may drag on for years. The catarrhal condition either originates in the nose and extends into the nasal duct, or it begins in the lachrymal sac and spreads down-