The hyaloid canal and its relation to cyclitic exudation / by Angus M'Gillivray.

  • MacGillivray, Angus.
Date:
1898
Catalogue details

Licence: Public Domain Mark

Credit: The hyaloid canal and its relation to cyclitic exudation / by Angus M'Gillivray. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    Angtis M'Gillivray In mammals before the closing of the choroidal cleft, meso- blastic tissue passes into the interior of the secondary optic vesicle. This mesoblastic tissue, together with a small quantity of mesoblast that has been carried in with the lens, forms the future vitreous. At first it surrounds the hyaloid artery, forming a canal or perivascular sheath, the hyaloid canal. The contents of the canal disappear before birth, but the canal itself remains patent throughout adult life as a slightly compressed tubular channel one or two mm. in diameter, beginning behind in a slight conical enlargement at the optic disc—area Martegiani, and passing forwards somewhat eccentrically through the sub- stance of the vitreous to the posterior pole of the lens, where it ends in a similar conical enlargement called the post-lenticular space. This space communicates with the patellary fossa in which the lens lies, and this again with the posterior and anterior aqueous chambers through the zonular spaces. Michel has injected the hyaloid canal with a coloured fluid by injec- tions into the anterior chamber, and Schwalbe has even suc- ceeded in passing the coloured fluid along the optic nerve into the intervaginal space, so that the hyaloid canal may be regarded as a lymph space communicating between the aqueous chambers in front and the intervaginal space behind. It is moreover one of the chief posterior lymph channels of the eye, with its outlet in the lymphatic spaces of the optic nerve. A cyclitic exudation, which is always more or less plastic, passes first into the posterior aqueous chamber, being the direc- tion of least resistance, thence into the anterior chamber, where the cells and lymph become agglutinated by coagulated fibrin into small masses of varying size. These agglutinated masses when tossed about in the aqueous whirlpool, become more or less rounded, and being, as a rule, too large to pass through the filtration area into Schlemm’s canal, they remain in the anterior chamber, and not unfrequently become deposited in a pyramidal fashion on the posterior surface of the cornea at the lower por- tion, as one sees in so-called keratitis punctata or Desceinitis. The exudation may, however, pass backwards between the lens and the patellary fossa into the post-lenticular space, especially if the posterior aqueous chamber be filled with exudation—total posterior synechia. Once in the post-lenticular space, the exuda- tion enters the distal end of the patent hyaloid canal, and then readily passes along to the optic disc. In this way an exudation cast, both of the patellary fossa and hyaloid canal, may be formed.